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Bringing Back the PDP8
Anne Thwacks writes " Andrew Grillet has decided that the Digial PDP8 - the first ever minicomputer, will rise from the dead.
He is calling it the PDQ8. Sure others have done software emulations, and even hardware clones, but he is not just building a hardware clone, but trying to revive the whole idea of 12 bit computers!"
...and I building a 3.5 GHz TRS80 with a GIG of RAM and 2 5 1/4" 80 GB floppys. its the cats ass
while the geek factor may be high, what sort of 12-bit software is it going to run ? linux?
An idea whose time has passed. Maybe he can build an Edsel while he is at it.
If you aren't part of the solution, there is good money to be made prolonging the problem
Personally I wouldn't mind to see it revived. I mean, anything has to be faster than an Intel Itanium.
Imagine a beowulf cluster of these!
On second thought, naah, don't bother...
Anyone for hitting up the local vacuum repair shop and getting started on an ENIAC reconstruction project?
Many of you probably have used Xilink's 1000, 2000, or 4000-series FPGA card during laboratories for your undergrad classes.
Well, if you'd like, you can follow this design of an FGPA implementation of the original PDP-8 computer!
If you've used Verilog (a hardware design programming language), like I have, you can even download all the code!
If you celebrate Xmas, befriend me (538
I found that, where you are not primarily handling ASCII, 12 bits was a very good size.
Maybe someone would enlighten the rest of us on why a certain bit size is better than another, and why we currently use 8/16/32/64, instead of 12/24/48/96 ?
Since the site is already /.ed i cannot read more about this or see any pics, but I have to wonder what good 12 bit technology would still be good for. I guess perhaps you could run a basic linux system with it, but what else?
[n8.r0n] http://petesweb.spymac.net/
I fondly remember the PDP8. My father had one installed in the garage when I was a kid, and had my first experience of programming on it when I was 8 or so.
On the subject of PDP8's, I was surprised to hear that they were used in communications in Hong Kong up until at least 1999 for a number of financial institutions. I worked with an old computer technician who earned a fortune maintaining these beasts. I wonder if they are still being used in HK after the Chinese reclaimation?.....
-- 7 string electric violin + live loop samplers
Down in under 5 posts, that is almost a new slashdotting record..
Sigs? We don't need no stinking sigs!
I guess he's using a DPD for his server.
Do not meddle in the affairs of sysadmins, for they are subtle, and quick to anger.
Apparantly, the PDQ8 doesn't withstand the /. effect very well.
And of course, obBeowulf.
Why is it that the proponents of "one nation under God" are so eager to get rid of "liberty and justice for all"?
but he is not just building a hardware clone, but trying to revive the whole idea of 12 bit computers!"
So, after reading the article, I am still trying to figure out....Why revive the idea of 12 bit computers? Other than nostalgia (which is why people still drive Studebakers, old Ferraris and old Porsche's I suppose), what is the point?
Visit Jonesblog and say hello.
people have been building replicas of old cars, boats and aeroplanes for years. i suppose its logical that people would start building replicas of old computers sooner or later. much computer hardware is boring these days, generic MBs and computers. ahh the good old days when we had some variety ;)
all power to him!
It would be fun to play around with something cool like that, just for the sheer ability to say "Hey, y'all watch this!" (Oops, better watch that there accent, ya rekcon?) It would especially nice to have a C compiler or something to develop apps for it, again just for the coolness factor.
With a twelve-bit computer, what is the address space, anyway? Something like 2048 words? Suprisingly, you can actually do a lot with that if you code it tightly. No, can't do weather map rendering too well or anything like that, but I bet you could pull off a stripped down version of NetHack or something...
Coolness, regardless. :-)
Be excellent to each other. And... PARTY ON, DUDES!
Well, I found this old link in my bookmark manager. It details the history of EMS (sound studio) in vivid detail, including a listing of all their original equipment.
The interesting part is that they posted high resolution images of their setup, which includes PDP-8 microcomputers!
The image: http://www.ems-synthi.demon.co.uk/studiopz.gif
The PDP-8s:
Left side - Teletype for PDP8
Left bay - PDP8/L Computer ("Leo") 4K x 12 bits (=6K bytes) 1.3 s cycle (0.77MHz), 32K Hard Disk Store
Center left bay - PDP8/S Computer
If you celebrate Xmas, befriend me (538
12 bit is much better for patriotic Americans.
Think on it, power of two is a far to simplistic and dare I say it European system for the patriotic American. In Europe they use metres, kilometers, grams and kilgrams. All this regulation of structure around a number like 10 is typical of Europeans. Americans use sensible systems like 14 pounds (abbreviated sensibly to lbs as pounds clearly contains the letter l) to a Stone and 16 Ounces (again with a sensible abbreviation of oz) to a pound. Who needs these ridiculous regimented European systems that dicate that everything must follow a sensible pattern?
Patriotic Americans arise. 12 bits to a byte, 7 bytes to a word, 13 words to a sentence and 1764 bits to a chain.
An Eye for an Eye will make the whole world blind - Gandhi
On a related note, I'm going to be designing my own 32 bit system. It's going to be pretty cool having an asthetically pleasing case, and run most all of the common software out there, but make the operating system run on top of bsd. Then I'll make really high-end systems, and education type systems, and laptops.
Now I'm 95% of the way done with this whole project so I've hired an advertising firm to come up with some commercials. I figure I'll show joe average sixpack switching from the normal x86 windows machine, to my machine, I'll call them 'Switch-Ads'.
My proprietary systems will never run on anything else, and you will be forced^H^H^H^H^H^H encouraged to only buy via our website.
I'll call them MOC's ... and the company will be named Orange.
Ignore the "p2p is theft" trolls, they're just uninformed
You need 7 bits for 128 characters symbols. With 6 bits you can have all capital letters, but not the lowercase.
:-)
With an additional bit (totalling 8), you have all the ASCII 128 chars plus another 128 for special symbols (line-drawing semigraphical chars and accented chars).
Once 8-bit memory modules (i.e., hardware chips) became standard, people joined two to build 16-bit memory words -- and then 32... 64... 128... ops, not yet
HTH.
8 bits should be enough for everyone.
From: http://www.grillet.co.uk/biog.html
"My mother was a Fortran programmer using computers that looked like this [picture of an ancient IBM 608-series supercomputer]"
If you celebrate Xmas, befriend me (538
DIdn't Intersil make a single-chip implementation of the PDP8? As someone noted earlier, this should pose no problem anymore; even an undergrad should be able to tackle it.
I build the first mnemonic memory circuit using stone knives and bear skins.
I remember playing the father of the Zork series of games on a PDP 11/35 which was the newer 16 bit machine. The game was called Adventure. We got the game on a 5 Meg 14 inch hard drive (RK05) and wasted a bunch of paper making moves on a keyboard/printer terminal. The scrollback feature of the hardcopy was great for finding your way out of a maze again. Adventure has since been ported to CPM and DOS. The game is still a great game and will challenge the thought process. Take a pencil and paper to keep from getting lost. There is no map. Do a google search to find this true classic game. You should be able to run it in a DOS window on Windows 95 before DOS and Windows 95 expire at the end of this year. I'm still trying to figure out who the shadowy figure is who tries to get my attention.
The truth shall set you free!
Never mind a beowulf...Imagine a wankel engine in one of those!
It was fairly easy to program for - I wrote a simple cross-assembler on a Dec-10 that would print out my assembler source with machine code (in octal). For short programs, it was fairly quick to enter the programs in octal. Since the Intercept Jr. was all CMOS, the programs would stay in memory as long as I wanted without runnng down the batteries.
Really, it was very cool, and fun.
-Mark
does that mean we get the PDP-endian nightmares back, too? And maybe ITS, too? (I'm quite sure I'm confusing PDP incarnations here, though)
Please correct me if I got my facts wrong.
We had one of these in high school (25 years ago), looking back I thought it was pretty cool but man that single DEC tape drive was a royal pain. We also had an old teletype with a paper tape punch, haven't seen one of those since. In my junior year we got a grant from the state and got a PDP-11 with dual 8 inch single sided floppies, now that was living!
I just dont see the point of resurrecting 12-bit hardware when we have 64-bit now. Why the nostaglia? PDP is dead! the world will never see another 12-bit. Is this guy a museum curator?
Somewhere I have an old DEC PDP-8 handbook. They released a native FORTRAN compiler for the PDP-8. It just shows what you can do with clever coding and lots of overlays.
Mea navis aericumbens anguillis abundat
I remember seeing one of these puppies when I was in high school. It was no longer in service, but still had most of its internal components. In fact, I still have one of the "flip chips" that I took from inside it. Anyway, I believe I recall a dial on the front of the main panel that allowed you to choose the word size. I can't remember whether 12 bits was the minimum or the maximum, though. Can anybody verify that this existed, or am I just remembering some strange dream?
GreyPoopon
--
Why is it I can write insightful comments but can't come up with a clever signature?
Yes.
--
Internet Explorer (n): Another bug -- that is, a feature that can't be turned off -- in Windows.
An interesting exercise for undergrads. If he used a Virtex II Pro he'd have upto 4 power PC 405's on a single chip (not to mention all that reconfigurable logic).
Now some real nice research would be to see how to those processors could be combined with reconfigurable logic to give some real power.
Sig (appended to the end of comments you post, 120 chars)
How can they possibly expect us to use the efficient new Radix-50 character encoding to store text? RAD-50 requires 16 bits to compact characters.
DeCastro was right, this 12 bit nonsense will never go anywhere.
Some mentioned earlier on this thread jokingly about making a super fast computer based on old architecture.
Has anyone actually done that? Has anyone actually taken say, a Tandy Color Computer 3's hardware and boosted it up to something approaching our current standards? I'm not talking emulation on a x86 platform. I mean fully working with a processor with a native OS.
Those architecture are so simple, with kernels so small you could print the hex binary out on a couple of pages. Imaging how fast an accounting package would be on a 1 gHz, or even a 200 mHz.
I know this maybe off topic, but if someone could resurrect a 12-bit system to a more modern standard, why not other system. DOS is still viable in certain circumstances, why not these platforms.
Think about an 8-bit controller with a serial connection, flash memory, and a RCA video out jack that is based on a C64. There is a TON of documentation for programming on something like that. Linux guruâ(TM)s could use C/C++ and Windows users could use Commodore BASIC.
Oh well thatâ(TM)s just my ramblings.
You say things that offend me and I can deal with it. Can you?
The PDP-8 wasn't bad for it's day. They even had a Time Sharing System that ran on it that gave each user a whopping 4 K of space do do whatever they wanted to do with it. It supported up to 16 simultaneous users. I know, I'm old enough to have gone to a college with one of those beasts as a shiny new grant from DEC. We had 2 high schools and one private school hoked up to us by the old 110 Baud ASR-33 teletypes. It was a hoot trying to make anything run on it. Assembler was about your only choice as Basic didn't have any file I/O until about 1973 - 1974.
Why bring it back? Why not? It may not ever be used for much, however who says all the cool computers have to be uber-machines? This next comment isn't meant to start a flame war, but I'd like to see some of today's bloatware folks try and make a program of any substance work on one of those puppies. I've seen some code from folks used to huge addressable and virtual memories and YIKES !
"Base 8 is just like base 10 really. . .if you're missing 2 fingers."
KFG
What else would be a 12-bit OS?
And of course
"with your bare hands?"
yes
you stand amazed as the dragon lies dead at your feet.
Bugger graphics you can't beat a maze of twisty passages, all different.... or was it a twisty maze of different passages.
An Eye for an Eye will make the whole world blind - Gandhi
If you look at old assemblers and compilers, the limit on the length of a symbol/variable name is often the number of characters that could be squeezed into a single machine word.
Mea navis aericumbens anguillis abundat
I "fondly" remember this as my first system I worked on.... We had three. Two of them didn't have a boot card, so you actually had to toggle in a boot loader program (around 20 or so steps). It was like playing a piano. They had 3 RK05 disk packs (1.5M each), 32MB of Ram, and a 300 baud terminal. But it handled 16 simultaneous users. It put out our newspaper every day for many years. They punched paper tape for output that we would run into type typesetting machine.
You know, I work with PDP11's day in and day out. DEC's last PDP processor was, I believe, a PDP 11/93. It has a whopping 2 MB of RAM and 8 serial ports on the processor board! This was a double sized board only taking up 2 slots on the DEC backplane that took the function of 5 boards that took up 5 slots each. Of course the disk controller, clock card and other boards are separate. These boards are circa 1990. They are in a custom digital dictation system that can handle 64 simultaneous audio ports where people are either dictating or transcribing. The OS is the roll off your tounge: RSX11M+. These systems, which we are replacing slowly but surely, have been absolute work horses lasting for at least 10 years.
:)
I jsut had to reboot one this morning...
Chris
Every rule has an exception, and this is the only rule with no exceptions! Huh? -- Spatch
...well, you could just omit using your thumbs...but that wouldn't be as masochistic (tango-y goodness!)...
Tom L. has always been a Haavaadite, not from MIT, as in the "Harvard Fight Song," and the lines, "These are the only ones of which the news has come to Haavaad/And there may be many others, but they haven't been discovaad." (Rhotic-lossy dialects bother me, since I speak one of the few English dialects that's fully rhotic.) I imagine it matters to some people (probably they go to Harvard).
Also, as far as I know, he's still there, although long since an Emeritus.
I'm not a geek, I'm just a clever script.
Doh! [check] Whew... got pants.
__________________________________________________ _
I smell a Wumpus! Shoot or move? [S/M]
Bruce
Bruce Perens.
Instead of a BSOD?
that's beautiful, man.
YOU FOOL!! This is slashdot. All you need is Linux.
a rough quote from Monty Python...
"I built the castle in the swamp. They said it would fall over but I did it anyways. Sure enough, it did. I build a second castle and that one fell into the swamp as well. But the third castle stayed."
Looks like he needs another iteration.
This space for rent.
Wow, 10 fingers, how many thumbs do you have?
thank God the internet isn't a human right.
I'm old enough to have done an electronics project building a joystick interface for a PDP8 as an undergraduate. I spent ages soldering TTL chips and after a few weeks plugged the card in, to a strong smell of fish and burning insulation. It wasn't my fault, the slot in the edge connector was too wide, and every single connector on the backplane had shorted to every other. It was 6 months to get the machine repaired, so someone figured out they could take out the power transformer, scrape off the burnt mess, figure out how many primary and secondary turns were needed on the transformer, then wind them on using a reel of wire and a lathe. They go the machine going, someone else filled the board slot with epoxy and cut a new slot. My project was saved! A few weeks later i reached round the back of a PDP8 to unplug a power connector, grabbed the live pin, but was saved because my arm was earthed to the PDP8 case. I love that machine, I still have the instruction set on a sheet of paper.
run your very own pdp8, pdp11 or even an Altair with disk basic or cp/m - here. I've recently completed some serious z80 assy projects using simh on my Linux notebook. Works great w/o having to mess w/ flaky hw.
try { do() || do_not(); } catch (JediException err) { yoda(err); }
Until I actually started programming a PDP-8 (in assembly language, of course), I would never have believed that you could program comfortably in such a seemingly restricted instruction set. And, conversely, when I moved to a PDP-11, I thought I was going to revel in the freedom and power of all those instructions, all those registers, those addressing modes, those index registers... and the ability to access 65536 bytes directly.
If C is "high-level assembly language," then the PDP-11 is "a computer that directly implements C."
To my surprise, though, I didn't really find that a lot was gained. Programming a PDP-11 didn't really FEEL much easier or more powerful than programming a PDP-8. And it was amazing how much every program expanded in size. It's been said that the PDP-8 instruction set was the most core-efficient ever devised, and I'd believe that.
On the other hand, when I tried programming a 6502, which on the face of it doesn't SEEM that much more restricted than a PDP-8, I just about went bananas.
Having said all that, I'm still not sure I see the point. The sweet design for a computer has to depend on the economics of the hardware around it. Who cares? Even IF the "core-efficiency" thing were true, and even IF you could use standard RAM with a 12-bit processor and not waste any bits, and even IF it turned out that the PDP-8 design were, say, 30% faster and used 30% less RAM for a given program than x86... how could it matter?
If the Alpha, which really WAS a superior design, wasn't superior enough to overcome Intel marketing, customer inertia, and only the normal amount of mismanagement, how can a PDP-8 be anything more than a curiosity?
"How to Do Nothing," kids activities, back in print!
I am really sick of /.ers asking "why do this?"
Why don't you actually use your overstuffed, overeducated brains and IMAGINE SOME USES FOR IT, YOURSELF!
Isn't that part of the idea behind open source? You build something for yourself, and then let others improve upon it. Why should it be so different when the project isn't implemented in software? It shouldn't. If you can't figure it out DON'T POST
http://en.wikipedia.org/wiki/Signature_bloc
Sounds cool, and reminds me of a project I've been tinkering with for about a year now -- a multiprocessor system based on the 6502 (actually, the 65c02), the same chip as was in the Apple II, Atari, the C64, and the original NES, among others. Problem is, my electronics knowledge at this point is not good enough to get beyond a good theoretical knowledge of what would be involved, though my 6502 assembly language skills are still sharp enough to write the firmware and software.
I only mention this because I hope someone who does have the requisite electronics skills will email me so we can join forces.
As for the earlier post to the effect of "what is it good for?", I can only say that it's fun to do, and old computers are good for the same things they were good for when they were new. One may as well ask what a 1965 Mustang is good for.
Proud member of the Weirdo-American community.
(Rhotic-lossy dialects bother me, since I speak one of the few English dialects that's fully rhotic.)
I'm assuming that the word Rhotic means including 'r' sounds in words. The definition couldn't be found on dictionary.com. Under that assumption:
Here in Picksburgh, all yins Stiller Fans know how ta wursh yins dishes, right ya jagoff??
The PDP-8 had a long life as the Decmate word processor, the 12 bit word did very well, as it could handle text, with bold, underline, etc directly.
The 3rd party service man at a VAX site I worked at in the early 90's had a PDP-8 (W/ RK05's!) still under contract in a big milling machine at a local heavy manufacturor.
Back then, the size of core memory was generally measured in machine words, thus in the case of a 12-bit machine like the PDP/8 with 32 k-words, the core would be: 32 x 12 bits == 384 k-bits, or 48 k-bytes.
In Soviet Russia, Jesus asks: "What Would You Do?"
The very first computer i have ever played with was PDP-8/e. It was "loaded" machine with 16 k words of RAM (magnetic core of course). The front panel of the machine had a row of switches that enabled direct, true "machine language programming". You were able to manually deposit words, both in registers and memory. Since PDP-8 was 12 bit machine it was natural to represent the machine word in Octal.
In order to boot system from scratch, you needed to deposit in memory ~20 word program called: "RIM" (Read In Mode). Once RIM is loaded it started punched tape reader in teletype in which you hopefully loaded "BIN" tape. Once The BIN program is started you had rudimentary OS for reading and running whatever programs you had on paper tapes. Most often we used "Focal", the interpreter very similar to BASIC. Later, we bought PDP-11 with 80 MB hard disk and multi user OS (note my user id), but "Eight" was the machine that hooked me for life.
That was the PDP-1, released in 1960, 5 years earlier.
The PDP-8's distinction was to be the first mass-produced minicomputer.
Thank $DEITY for kilograms, a sensible unit.
-Dom (an anti-imperial uk denizen)
Here's google's cashe.
This is by no means a new or unique project. PDP-8s have been cloned using various chips for years. There is the SBC-6120, the PDP-8/X and many others.
Of course, none of these are as much fun as the real PDP-8/E and PDP-11 I have in my basement.
C compiler indeed.The PDP-8 was natively a FORTRAN machine. Apps can be developed perfectly well in FORTRAN. . . and the coolness factor is higher.
.
l
u se um.html
King Arthur: Noble FORTRAN compiler, although you are a dead language. .
FORTRAN compiler: I'm not dead yet sire.
King Arthur: Although you are a mortally wounded language. . .
FORTRAN compiler: Actually sire I'm feeling a bit of all right.
Again, C compiler indeed. Gag my PDP-8 with a spoon. ( Actually, that would be 'anatomically' possible)
Here's an interesting little page on the history of the PDP-8 OS's and languages:
http://www.cs.uiowa.edu/~jones/pdp8/history.htm
And here's an interesting computer history page with several FORTRAN links ( as well as UNIX and C links):
http://www.fortran-2000.com/ArnaudRecipes/CompM
C compiler. . . phbbbbbt!
KFG
Let it RIP.
Contrary to popular belief, coding is not all free blow-jobs and beer. Those things cost MONEY!
I would love to see someone put together a CDROM or a DVD of emulators and the history of the original harware complete with pictures. Can you imagine being able to browse through a history of 1000's of machines and actually be able to run an emulator for any of them.
It would be like a digital museum of the history of computing. Wouldn't that be appropriate?
I have an emulator for the C64 so that I can play a lot of the old games. I also have put together a mame based video game box, full sized. The thing stands 6 feet tall. Inside is a pentium 100 running an emulator so it will play old games like star defender and Q-Bert.
As far as hardware goes, I believe that if I had an 8-way AMD sledge hammer with 32 GB of RAM and 100 Terabytes of RAID drive space then I would never need another new machine again. I just need smart terminals that all hook into the central computer to display results and control events.
... someone's noticed !
In any case, wasn't Conway's original Life written to run on a PDP-7 ?
I did write some s/w for that very machine - in BCPL - had to take the paper tape down to the machine room containing said PDP-7 and a couple of Data General Novas (Novae).
Its attraction was that it had a vector graphics display, presumably why Conway used it to run Life.
Kids of today ? Don't know they're born !
and "taler" comes from the town of Joachimsthal, where the silver was mined.
Best Slashdot Co
Transmeta uses a VLIW (Very Long Instruction Word) technology. How long I did not see in a brief glance, but according to this article they have used 128 and 256. They do this as a way of encoding parallelism. Graphics processing also tends to have a lot of implicit parallelism which long instruction words help with. Both dedicated game consoles (eg the playstation) and graphics cards migrate to longer words much faster than general purpose computers. Years ago the 64 in Nintendo-64 was because it was a 64-bit computer. These days 128 and 256 bits are commonplace, and at least one 512-bit GPU exists.
I recall that OS/8 failed horribly on the Y2k testing front.. wonder if he's got to set his clock back to the 70's all the time?
This configuration sounds amazingly like the priceline.com supercomputer that Capt. Kirk's been seen with recently...
These dudes beat you to it.
Steve
Only official support for them will. DOS will never 'expire.' It's done. Of course you can't buy MS-DOS anymore, but there's always DR-DOS and FreeD0S, both still supported.
W95/98, on the other hand, will actually expire some years in the future. I discovered this on a reinstall that went bad. Windows simply refused to install. Having a Gateway at the time I called tech support and the issue was tracked down to a buggy BIOS (gotta watch for those updates) that had reset my system clock to a future time.
"Ah, there's your problem. Windows has a 30 year time bomb built in so it thinks it's expired."
Ummmmmm, good to know. I guess that's how long we've got to port all our favorite W95/98 games to Linux ( or maybe Plan 9).
KFG
12 bits is about the least you can get away with and have a usable computer.
Tell all the former 8bit CPU (6501, Z80, etc) users that they did not have a usable computer?
I don't think there's any fundamental DISadvantage to using 12,24,36 and 48 bit words and addresses. The question is not whether the memory addresses will be in terms of some power of two (of course they will), but whether the sizes of words used to hold values and addresses should likewise be an even power of two. Even numbers, surely, but not necessarily a power of two bits wide.
At the time when things pretty much fell into the currently accepted pattern, word sizes that were even powers of two happened to be convenient:
2^8: enough to hold the complete latin alphabet
2^16: Enough bits to handle the entire address space of a 1980s microcomputer
2^32: Enough to handle almost any day to day integer calculation
It's like the inch-foot-yard-furlong-mile of English measurements. These are well suited to the kind of day-to-day measurements that people make, as inconvenient as they are for calculation. Eight, sixteen and thirty two bit words and addresses were big enough in the 1980s, but not so big as to be wasteful.
It's interesting to speculate how things might have been different had the industry settled on twelve and twenty four bit word sizes. It may have been more convenient for people with non-latin alphabets, although not as commodious as a sixteen bit per charcter system. And a lot of effort was wasted in the nineties with the limitations of sixteen bits address spaces (the segmented memory architecture, near and far pointers etc). The need for a larger flat, memory space might have been staved off for several years until 16MB chunks were too small.
I don't know if that's a good thing or bad thing. We might be struggling with a 24-48 bit conversion today instead of happily using our P4s and Athlons and waiting for the high end users to hash out the 32-64 bit conversion.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
The Harris HD-6120 "PDP-8 on a chip" is still available, and is what this guy is using:
- 2. htm
http://www.sparetimegizmos.com/Hardware/SBC6120
The only point I could see in using FPGAs would be if you were trying to rectreate an early MSI PDP-8 (these things existed before the single-chip microprocessor).
why disdain the past? Who knows, maybe your grandma knew something about sucking eggs that you don't.
If nothing else the guy is obviously having fun. Believe it or not when you get to be Eleventy years old your own hobby just might turn out to be keeping 16 bit Intel stuff alive.
I mean like, why ride skateboards when we have bicycles now? Why, because you *want* to.
KFG
But why the hell would anyone still be running Windows 95 in 2025? Or running games which run on Windows 95 in 2025?
Much better things will be available by then.
"Information wants to be paid"
Forget the PDP-8, give me a PDP-15 any day!
Talk about geek factor. We had a PDP-15 in the sub-basement of our Math building collecting data from a Van der Graf accelerator.
Then I would have a use for my HP-16C Computer Science calculator, you know the one that did conversions to/from Octal/Decimal.
Those were the good old days.
Those were the good old days.
They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.
I remember the place I was working in the mid '80s had a boatload of DECMate systems. They used a microprocessor based on a PDP-8 architecture. I bet you'd still find one of these in the junk bin at your local computer recyclers.
the upgraded CoCo was called. . . a Mac. You can still buy 6800 series chips, although you have to hunt around a bit. They're still very usful for a lot of things.
A C: www.ebnonline.com/story/chipwire/OEG20000927S0018+ z80+chips&hl=en&ie=UTF-8
On the other hand the venerable Z80 not only has never gone out of production but is being updated just as you suggest:
http://216.239.39.100/search?q=cache:vPeP4Ne7p1
There are an awful lot of uses for small, fast, cool running, general purpose and cheap as penny candy chips.
"Charles Luther" in "Runaway" understood this full well when he used 8088's to power his nefarious robotic killing machines.
KFG
It existed until the 60's. There was a fair amount of Lore around the Daler, notably used at Brothels for depositing payment at a certain part of the girls.
Help fight continental drift.
I loved programming the 6502, but could never stomach the crappy x86. The best environment for programming assembler, however, was the 68000 series...
GCHQ Quantum Insert installed. If only our tongues were made of glass, how much more careful we would be when we speak
The PDP-8 was not the first minicomputer. As its name implies, it had predecessors, including the PDP-7, PDP-5, PDP-4 and PDP-1. I nominate the PDP-1 as the first minicomputer.
Also, the IBM System/360 was not the first computer with variable-length instructions. The IBM 1401 also had variable-length instructions, and I am not sure it was the first.
John Sauter (J_Sauter@Empire.Net)
As nice as a base-3 system my be in theory, there are very good reasons for sticking to a base-2 system in hardware. As we are moving to smaller and smaller fabrication processes, it is necessary to lower the supply voltage Vdd. For example, now that we are approaching the 0.1um and 900nm levels (at least in research labs), Vdd is getting down around 1 Volt. However, the Vt (the threshold voltage needed to turn "on" a MOS transistor) stays the same, because it is determined by physical properties of silicon (mostly). That means we're losing headroom. To implement ternary logic, we would need 3 different voltage levels. We're simply running out of room to do things like that. You need to leave a noise margin around your "1" and "0" values for reliable operation. (For example, if Vdd=1V, you might consider 0.0-0.4 = "0", 0.6-1.0 = "1". Then a logic gate that "sees" 0.0-0.5 interprets it as "0", etc. If you had a "0" that was really 0.4V, you would hope that "noise" wouldn't bump it up above 0.5V, or else it would look like a "1".)
The threshold voltage for transistors is somewhere under 0.2-0.3V usually (depening on the technology & lots of other parameters). So, you absolutely need a 0.6V supply. (0-0.3 = "0", 0.3-0.6 = "1".) Unfortunately, even with Vdd=1V, you'll get voltage drops happening throughout the chip ("IR drops" - as in I=current times R=resistance) so that the 1V may only look like 0.8V to some parts of your circuit.
From the above discussion, it should be obvious that there really isn't room to shoehorn in a third voltage level. Also, a nice feature of CMOS design is that when a gate is sitting in a "0" or a "1" state, it is drawing no (well, negligible) power. Power is only dissipated while a value is switching from a 0/1 or vice versa. Off hand, I can't think of a way to do that with a third logic-value. Consider drawing even a tiny amount of current while a gate is sitting at logic "2" (or whatever you want to call the 3rd value). 1mA (milliAmp) times 1 million transistors on a chip = 1000 Amps. That chip's going to get a little hot!
Ok, so you've probably got at least two questions, which I will try to answer in advance. If you've got other questions - I'll just let someone else tackle those.
Q1) Why don't we just use a higher Vdd (supply voltage)?
A1) If you're using smaller transistor widths, you simply can't. When you use a really thin gate (i.e. 0.1um) on a transistor, the breakdown voltage of the gate is reduced. If you use a higher voltage, the transistor melts. (You could use larger transistors, but that kind of defeats the whole purpose! We make transistors smaller because we can fit more on a chip, and they operate faster and use less power.)
Q2) Can't we lower the threshold voltage?
A2) Yes, to some extent. (It's not always easy.) But we don't want to. Even when a transistor is "off", there is still a very small amount of leakage current flowing through it. If you reduce the Vth, you also increase the amount of leakage current. In older technologies, this hasn't been much of a problem, because the leakage current was so small in comparison to the dynamic power consumption. But as we are putting more and more transistors on a chip, the leakage power consumption in modern chips can easily add up to 30%-40% of the total power consumption. There's also another reason. If you did that, you would be lowering your noise margin. And you don't really have much control over the noise (which is why it's called that). If you reduce noise margins too much, you'll find it almost impossible to create a circuit that actually functions reliably.
Well, I hope that satisfies some of you (and doesn't get the rest of you too upset). VLSI circuit fabrication is a really neat field. Some of the tricks that are being used these days to fabricate that chip sitting in your computer and get it running at 2GHz (or aren't they up to 3GHz now?) are quite amazing - they're doing their best to cheat physics! Using a ternary counting system to build computers may have a lot of nice theoretical properties, but I can't see it displacing binary any time soon, except possibly in some really specialized applications. (There are always exceptions.)
That's my $0.03 worth. (Hey, I typed a lot. I think that's worth at least $0.01 extra. Maybe $0.025?.) Any errors in the above are mine, but I won't admit it.
There was a Coco 4, sort of. I don't remember much about it, I think it was the Tomcat, and I seem to remember Frank Hogg Labs having something to do with it. IIRC it had sort of a backplane, like a super multi-connector.
There was a class of 68000-based machines that ran OS/K, which was the 68k version of OS/9, or OS/9 was the 6809 based version of OS/K. Maybe it still runs on newer 68k architectures... that would be your Super Coco.
I have often thought of just running CP/M natively on my P4, just for kicks, but then I begin to realize how much that idea sucks. It gives you that feeling for a moment that you can start over from the point in time just before Microsoft subverted CP/M (ok, actually MS-DOS was somewhat of an improvement,) and let CP/M re-evolve into something you could really use.
And I thought I was old fashioned, owning a PDP-11..
Tom has always been a *student* of Ha'vard, Tom's spelling, ( as has been most of my family, I'm the "black sheep" and went to Bard), but he spent some years teaching at MIT. He also spent some time teaching at UC Berkeley, where he not only taught math but. . .musical theater.
I chose to highlight the MIT link because of their infamous connection to the PDP line of computers.
And yes, he's still at Ha'vard.
KFG
You are beating a dead horse if you think anyone would look forward to such a venture. This looks like a lame ploy to get some VC fundage. This might have worked 2 years ago, but it's not going to work now. 8bit is already entrenched, and is here to stay. Who would want a 12bit computer when you can get a 32bit one for cheaper and runs faster? 12bits had its day with the PDP when all that was done was text processing, but I fail to see the relevancy of bringing back the 12bit processor of the PDP.
an object may have a proper noun all to itself and still retain membership in a larger general class.
Just as a "Seacock" and a "Butterfly," despite having proper nouns of their own are, nonetheless, still just valves.
Draw the Venn diagram, you'll figure out the set/subset relationship eventually.
In short, I have just as many thumbs as I have "pinkies."
KFG
Chess, Checkers and Go, even though "better" games have been available for thousands of years.
And by the way, Infocom rulz d00d!
KFG
The Studebaker only makes sense when you want to use one general-purpose tool both for the acquisition and the laying. This does work, but the acquisition performance is inferior.
For some industrial control jobs, something like a PDP-8 or PDP-11 is in many ways ideal because you can see everything that goes on. It is actually possible for one person to understand the hardware, the microcode, and every single bit of the software. For me, that is the great pleasure of small embedded designs. I really think it would be good to have a teaching tool for CS that actually meant that the student could do a project and have a complete overview of the entire thing in this way. I'm far from knocking progress, but there are comments on this thread that are a bit about the kind of alienation we have now between hardware and software - most people have no real idea at all what the hardware does, and use terms like "cache" without even stopping to think about what is going on. So yes, let's have someone build an understandable modern PDP-8. It's less weird than the RCA1802 and easier to get your head around than the 8080.
Panurge has posted for the last time. Thanks for the positive moderations.
Hey, did you watch "Connections" too? That's kind of an obscure factoid, and I'm wondering where else it shows up.
--grendel drago
Laws do not persuade just because they threaten. --Seneca
Actually...
Here it says:
The meter (m) is the Si unit of length and is defined as the length of the path traveled by light in vacuum during the time interval of 1/299792458 of a second.[3] This replaces the two previous definitions of the meter: the original adopted by CGPM in 1889 based on a platinum-iridium prototype bar, and a definition adopted in 1960 based on a krypton86 radiation from an electrical discharge lamp. In each case, the change in definition achieved not only an increase in accuracy, but also progress toward the goal of using fundamental physical quantities as standards, in particular, the quantum mechanical characteristics of atomic systems.
--grendel drago
Laws do not persuade just because they threaten. --Seneca
I visited them recently, and it is wonderful to see all these PDPs restored. I havent seen a PDP-1 before! I suggest computer history museum in silicon valley for you all. Check out their website.
http://www.computerhistory.org/
on what other computer can you have this instruction, given you have a memory location with the right label:
TAD POLE
ha!
Intersil used to make a CMOS microprocessor chip that used the pdp8 instruction set. It was a 12 bit micro processor. They also made a chip that acted as the memory address extension controller. You still might find some of these chips for sale someplace. DEC even used the 'cmos 8' inside one of their terminals to run pdp8 based word processing software. If you want to build your own pdp8 today, I'd look for some of those old intersil chips.
He's been at UC Santa Cruz since the early '80s. He teaches "The history of the American Folk Musical", IIRC.
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
Who??????
Back up that "True American Hero" statement with facts that those of us who are unfamiliar can understand.
reassign null to be the tape device - it's so much more economical on my time as I don't have to change tapes_BOFH
I used to repair PDPs and Novas for a living before I got into programming (MUMPS, in case anyone remembers that), so I have a certain interest in this story.
:)
Still got the scar from a Nova 4 power supply which zapped me - geek chicks dig that sort of thing
I'm surprised nobody has mentioned the fact that Unix was first developed at Bell Labs, by Thompson and Kernigan on a PDP 8.
Sandy
Yes, but he's bicoastal, just as in his UCB days. His home remains in Mass. and last I knew he still maintained "ties" with Harvard ( but then one of the problems with becoming an old fart is that "last I knew" turns out to be about 1980 which you think of as "just a while ago").
I could recall this wrong, but I think at one point he was, at least officially, teaching at Harvard, MIT and UCB all at the same time.
( And note that I make no claims to know the man, I just know several people who know/knew him)
KFG
We had an -8 and an -11 at my high school back in 1981-1985. We used to sing the Batman theme music whenever the service guy showed up to do PM on those washing-machine sized disk drives (RK07? gawd it's been a long time...):
Na-na na-na na-na na-na, DEC-Man!
Guess if it's the PDQ now, it'll have to be DEQ-man...
Fuck the people who decided our thumb is not a finger. Who are THEy to decide this? The every day person throughout the every day world considers it a finger. so fuck them who decided we are stupid if we consider it a finger.
A Good Troll is better than a Bad Human.
I'd say your chances of getting laid are better if you tell 'em you're resurrecting a '53 Corvette than a PDP-8.
--- I wish I could hear the soundtrack to my life. That way I'd know when to duck.
I termed FORTRAN "native" to the PDP-8 ( and I suppose it would only be correct to term the appropriate assembler "native").
It would be more correct to merely note that FORTRAN was the first 'higher' language for which a compliler was available.
I've at least seen FOCAL. I've *never* seen BASIC on a PDP-8 ( thank God), but my experinece with the machine was strictly in a hard science academic setting where FORTRAN was King.
Don't get me wrong though. I'm no FORTRAN zealot. I'm an APL zealot who always resented the forced move from one to the other.
KFG
The LINC computer (http://www.mit.edu:8001/people/ijs/epl/LINC.html) preceeded the PDP. We had one in a lab at the Northwestern School of Medicine. We used it for fourier analysis with output to a Calcomp plotter. Sixty four data points, took 5 minutes! Those little DEC tapes sure were churning! Also, used it to emulate a computer of average transients. fun machine to play with. 4K of memory with only 2K that could be used for program.. With creativity, one could do a lot with that machine! :)
"Gentlemen, you can't fight in here! This is the War Room!" -- Dr. Strangelove
"The PDP-8/X is a reimplementation of the PDP-8/I, with 32K words of memory (all the memory you can put on a PDP-8/I), an extended memory control, an interface to an RS-232 terminal, and an interface to an IDE disk, which I built just for fun.
I consider this machine to be a new model compatible with something from the past, as opposed to a clone of the past, so I feel no shame in introducing new model-specific variations. The PDP-8/X, therefore, uses IDE disks with a new disk interface, because I thought that it would not be unreasonable for a new model to come out with a new disk controller, especially considering that customer-written PDP-8 device handlers were both common and encouraged."
He also did a PDP-4/X.$ find
OS/8 couldn't possibly have failed on the Y2K front; it had no concept of time. The operating system even ran without interrupts.
Now you've gone and done it! Our knock is no longer a secret!
Whoops; forgot that OS/8 did have some support for the date. You could issue a command to set the date and it would tag the files it created with the date.
However, OS/8 failed the Y2K problem in 1978. That's why OS/78 was created; it basically moved the epoch to allow dates in 1978 and beyond to be represented.
Shuttle XPC (nice and quiet)
Apple Cinema (only the 22-inch version)
2.4-GHz P4 (performance is OK)
1 Gbyte RAM (a reasonable amount)
80 gbyte disk (plenty for now)
Nice and cheap...
I still have several plots generated on a PDP-8/L, drawn on a Hewlett-Packard X-Y recorded through the D/A outputs.
<slightly offtopic>I stay away from WinXP for the second reason: I will not allow someone else any sort of control over my machine, especially god-like without explicit direct authorization! In exchange for which, I recognize the rights of authors and work accordingly.
</offtopic>
Was the story a myth, that these boards were knitted together by hand on the Navajo reservation?
Hey I remember that, but I always thought it was the choke.
Those darn researchers, what will they think of next.
bi-quinary is 2 bits on of 5 bits total which gives exactly 10 valid combinations.
IBM 7070 and 7074 (2nd generation mainframes) were bi-quinary, 10,000 10-decimal-digit words with THREE signs (plus, minus, and alpha)
IBM 650 IIRC had 2,000 10-digit words on a magnetic drum.
A long time ago I had an HP 55 which IIRC almost exactly matched the specs of the ENIAC, something like 20 words storage and 50 programming steps.
Ok, i don't know anything about Rolls-Royce cars (or houses, either), but what the Hell, $18'000 seems JUST a touch too low for a "top" Rolls-Royce. An entry-level Beetle costs $18'000.
If this thing fits on a single FPGA, then it could be made into a handheld called the PDA8.
-- Ed Avis ed@membled.com
I used to work for Digital before Compaq took us over and the Digital name died right there. Now that HP has taken over Digital - Digital is deader than dead!
Perhaps it is time for a new logo for the topic (RIP comes to mind)
NB: Digital was the best company to work for...
From excellent karma to terible karma with a single +5 funny post...
We used the PDP8 as a learning tool in a hardware class. Built a PDP8 using wirewrap and Programmable logic arrays, then tore it down and rebuilt it using Microcode. It was pretty cool - had a variable clock, single step for debugging, serial i/o.
Course number used to be C421/422 at Indiana University. Text was "Art of Digital Design" by Prosser and Winkler. Kits may still be available.
One of the cool things about TOPS-10 was that it allowed the programmer to define the bytesize for each program. There was nothing sacred about 8 bits. You used whatever size fit your datatypes best, even if it wasn't a factor of 36. Even 36 bit bytes were possible, although kind of pointless.
Tying byte size to datatype made byte instructions much more versatile, and made for much more efficient use of memory at a time when people spent as much time making their programs fit as they did making them work.
Another cool feature of the 36-bit instruction set was that every instruction was one word long. Made for very elegant programs. It was RISC back in 1964 - maybe there'd be a place for a 36-bit RISC system today?
Our DEC-10, s/n 2393, regularly supported 70 to 100 simultaneous users, with half of them running database searches most of the time, and with response times below one second most of the time. That's from a processor that would be rated at 1 MIP by today's metrics, and 4 megawords - about 18 megabytes - of memory. Imagine what could be done with that kind of efficiency on today's machines.
Why would anyone be running Windows 95 in 2025?
Everyone, no.
Anyone, why not. Why would anone be interested in a thousand year old garbage dump?
Time bombs may have uses, but eventually they will bite back in places you didn't know you had places. With a time bomb built into W95, you have to wonder what Microsoft has built into XP and successors.
You could buy a Beetle for less than $2000 back then. A Rolls Royce started at about $20,000, about the same price as a new single-family house in what was to become Silicon Valley. Isn't inflation wonderful?
Mea navis aericumbens anguillis abundat
But why the hell would anyone still be running Windows 95 in 2025? Or running games which run on Windows 95 in 2025?
Ask the man with the beard and the Dec-PDP8. He speaks in 12 bits. He knows everything!
Any proper thread about DEC PDP gear should not have the **SILLY** 1990's logo from the Palmer era, but the original "real" Digital logo - just the way KO created it.
-AC-
...Imagine a beowulf cluster of those!
Does anyone run these any more?
I'm still scared from years of having to "support" a few of these things.
To refresh the memory of anyone who cares, they from an OS called AMOS (the company was called Alpha Micro, okay) and they were 68000 based multi-user (clears throat) "mini" computers.
Oh, and they crashed quite a lot too.
The Fall issue of Invention & Technology has an excellent article on the rise and (not so) fall of vacuum tube technology. It also mentions the possible use in the future of nanotriodes: a vacuum tube-like structure a millionth of a millimeter across. So there ya go, ENIAC on a chip may be possible, complete with 'tubes :)
Dude...keying in the boot loader is krusty, though I was much dissapointed to read that he won't be gen'ing up the tape machine as well...pussy.
Dec also had a variant of the PDP-8 known as the Linc-8. It had a different instruction set but had built ADC/DAC/display and two Linctapes (which were like Dectape except they ran the other direction). It was intended for lab instrument monitoring etc. I ran one doing nuclear medicine image processing for perhaps 10 years in the 70's. We had 2 Diablo 33's for disk drives (like RK05's)and about 70 mb of offline disks stored in a cabinet. We discarded the ASR-33 and had an industrial strength ASR-35. Programmed in assembler on it for many years---ahhh the memories!!
Those architecture are so simple, with kernels so small you could print the hex binary out on a couple of pages. Imaging how fast an accounting package would be on a 1 gHz, or even a 200 mHz.
If they do reconstitute the 8080 and a couple peripheral chips for it (like clock, uart, parallel-port), I recently found the source listing of an RTOS I did for it.
- ROMable
- Real-time
- Preemptive multitasking (arbitrary number of priorities)
- Reentrant code
- Application and driver tasks are "actors". (Think "objects" where each instance of a task object subclass is a thread of execution).
- Intertask communication supported by the kernel was:
- Semaphores
- message queues ("communicating semaphores")
- freespace memory allocation queues
- Written in assembler, but with a system service calling convention compatable with the CP/M compiler output's subroutine calls.
The kernel, queueing system, idle task, init routine, memory allocator, and an "empty" (just the idle task and stop flags) task & preallocated memory table totaled a few bytes under a half-K. (Yes, Virginia, all that in less than 512 bytes.) Or a few bytes over if you want to keep some extra per-task state so a debugger can figure out what a task is up to.
The size was very important, because the system it was written to run in had only 8K of ROM available, max. This had to hold a complete energy management system, including OS, device drivers, real-time task debugger, com stack, real-time clock handler, schedule handler, command interpreter, data collector, thermostat input, relay contact input, event counters (watthour meter data collectors), relay drivers, relay logic simulator (ladder-diagram interpreter), and a table of relay logic to simulate. The total software came in under 4K, leaving one of the two ROMs available for the relay logic, sensor, and other configuration definition tables. (At a couple bytes per relay contact and a bit per interconnect you can define a VERY complicated hunk of relay logic in 4K. B-) )
The trick was the insight that adding Mark Weiser's "T" (non-blocking "P") to semaphores' "P" and "V" lets you use communicating semaphores for EVERYTHING, including communication between the below-the-line interrupt routines and the above-the-line part of device drivers (which compete with other real-time tasks in the normal scheduling process). Think "message-passing minikernel", with a vengance.
Religiously using communicating semaphores, in a handful of idomatic ways, for all intertask communication (and even some task-internal functions), makes the tasks themselves tiny, and leads to a software organization that amounts to object-oriented programming. (I believe that this effect, in a direct ancestor of this operating system, IS the origin of OOP.)
I kept the rights to the supervisor core and tools, and had been thinking of open-sourcing it if I ever found it again (which I now have - at least the hardcopy version). Let me know if anybody needs it and I'll get in touch.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
whatchoo talkin bout, foo?
thanks, I didn't know about the | in vi. learn something new every few weeks, still... [and it's been about 3 years]
heaven
You might be interested in taking a look at the CommodoreOne project:
e s.com/cm_easy/comone.htm
m drone.html:
http://www.commodoreone.com
http://www.geociti
It's a modern C64, but perphaps the most interesting fact is that it can be modified with different CPUs.
From http://www.geocities.com/profdredd/commodoreone/c
"What's this I hear about a 6510 being used as a second processor?
I've added a port that a cpu card will plug into on the new revision and someone can plug a 6809, 6502 or what ever into it. The CPU card will be able to carry the 65816, 6502, 65C02, Z80 and 6809. This will enable the C-One to act like nearly any computer of the 80s just by exchanging the CPU card and the program in the CF card. And yes, the 6510 ports are simulated, and yes, it's possible to add interfaces on the CPU card. The slot will be documented, so third party companys can produce hardware for it"
Now that's just sad.
You need a password to even access the site, making the links worthless. That just proves the stupidity behind this scheme.
There, I didn't bother to ask "why?". I conclude that there is no useful purpose for this so it should be abandoned.
If you can't figure that out DON'T POST!
Officer: "How many fingers am I holding up"
Drunk: "Well I've had about 20 fingers, and your holding me up, so I guess 20"
thank God the internet isn't a human right.
The Commandments of the EE:
(9) Trifle thee not with radioactive tubes and substances lest thou
commence to glow in the dark like a lightning bug, and thy wife be
frustrated and have not further use for thee except for thy wages.
(10) Commit thou to memory all the words of the prophets which are
written down in thy Bible which is the National Electrical Code,
and giveth out with the straight dope and consoleth thee when
thou hast suffered a ream job by the chief electrician.
(11) When thou muckest about with a device in an unthinking and/or
unknowing manner, thou shalt keep one hand in thy pocket. Better
that thou shouldest keep both hands in thy pockets than
experimentally determine the electrical potential of an
innocent-seeming device.
- this post brought to you by the Automated Last Post Generator...