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Don't Nurse Old Hardware - Emulate It
gManZboy writes "Bob Supnik, former team lead for DEC's VAX microprossesor, has an article up on Queue about his Computer History Simulation Project and how emulating old servers may be a better way to keep them running that servicing the physical machines. So how many PDP-11's can you run on a Pentium 4 anyhow?"
to add to the parent, companies like Intermedia will convert/image your disks for you.
So how many PDP-11's can you run on a Pentium 4 anyhow?
You could shell out some bucks for Ersatz11 and find out. It runs under Linux, and it runs fast. You can even attach Q-Bus and Unibus hardware with an adapter.
Here come da fudge!
Emulating a 5.25" isn't actually 100% necessary. The FDC that controls a 3.5" floppy is quite capable of controlling a 5.25" floppy in all three modes (DSDD, SSDD and SSSD) for reading any 'PC compatible' formatted disk. There are also a number of hardware options, such as the CatWeasel, that cen be used to drive a standard 5.25" drive to read non-PC Compatible disks.
Admittedly, you're still probably better off just using such a drive to create images of real world disks. Emulating drives with images is something that has been the core of almost all emulations of disk-enabled devices
The big problem, as far as I can see it, is reading 8" discs (as these do not, I believe, use the same controller as the others), or proprietry discs.
Such a "translation" would be beyond meaningless. The architecture is fundamentally different, and most of the P4's cycles would have to be spent on emulating/accounting for quirky little hardware details or features. That's why it takes a 100 MHz Pentium (if not more) to properly emulate a 1 MHZ C64
The illegal we do immediately. The unconstitutional takes a little longer.
--Henry Kissinger
I've used Bob's emulator a bit, playing with the PDP-11 emulation when I had an 11 in my basement that was failing. I now use the VAX emulator running BSD. I've also used SIMH as inspiration for my own emulation project for emulating a MITS Altair 8800 (with the front panel).
The next version is done and will be released within the next week or so after I update the docs to synchronize with the changes made.
Anyway, the project page is here:
http://highgate.comm.sfu.ca/~rcini/classiccmp/Alta ir32.htm
Funny? That should be modded 'informative.' I've never been hospitalized, but I did wind up with a wrist brace for a week or two thanks to some RA-92 hard drives.
Seriously, if anyone wants a free VAX 6000-510, let me know. I need the garage space back. I'm on the central coast of California. I'll even throw in a MicroVAX II or two if you want. They make good end tables.
For those interested in trying VMS on Linux using the SIMH emulator (entertaining if you once used it), I've written a set of installation instructions that might be of some use.
Phil
the PDP-8/e Simulator for Macintosh is a LOADED system (up to 32K words of memory, KE8-E Extended Arithmetic Element, ASR 33 Console Teletype, ASR 33 Auxiliary Teletype, PC8-E High Speed Paper Tape Reader and Punch, RK8-E Disk Cartridge System, LP8-E Line Printer, and a KC8-EA Programmer's Console) that runs a quite a bit faster than the original - fastest benchmark is a G4/450 at about 22x; my 2x1.25 runs the tests well under 1sec. If you need to support an -8 legacy, this seems like the logical way to go.
Facts do not cease to exist because they are ignored. - Aldous Huxley
During a high school internship. Fascinating machine. Back then, I think it was around 84 or 85, this machine served around 5 people on plain text terminals, and as soon as you started an integrated pascal compiler everybody complained that the machine was slow as a dog. Needless to say, that the pascal compiler was slower than Turbo pascal on a normal PC (given the recursive descension nature of turbo pascal no wonder, although the pc was myriads slower) But one thing I never saw with this machine, it never fell, and the multi language binaries, as far as I can remember where you could hook different languages easily together were really nifty. No wonder the company used this machine mainly for development and holding customer data, this beast was as solid as a machine could get.
How are you going to emulate a 5.25 inch drive to read old disks?
Write really good software! Even the Apple II Disk II drives, which depended heavily on the CPU have been emulated at the hardware level. Rather than reading sectors from a file, some image formats contain the stream of bytes read by the drive hardware. [Data encodings, bytes per sector and address and data marks were defined in *software* rather than by a disk controller chip. There were a large number of screwball formats, particularly in copy protected game software.]
...is that through resources such as Ebay, half.com, your local public library, garage sales and thrift stores, you can still get manuals for such things -- AND CHEAP! I found a PDP-11 technical programming textbook at my local Goodwill for a buck.
The Net is awesome for finding any used or out-of-print books or manuals of any kind - it used to take months to find something unusual, now it can be in your hands in a couple of days. Here are two valuable resources:
http://www.bookfinder.com/
http://used.addall.com/
You can do your own shopping at thrift stores and yard sales, finding the occasional RCA Receiving Tube Manual and such (I've done that a lot and now have about 10k books, including 20 tube manuals) but this is hit-or-miss for something specific. For a few more bucks per book, you can often find exactly what you want at one of the metasearch sites above or (if it has an ISBN number) used on amazon.com.
If you still don't find it, you can subscribe to this list:
http://www.bibliophilegroup.com/ ($30 per year subscription, two week free trial)
and send a WTB: (Want To Buy) post, where hundreds of used book dealers have large portions of their inventories they've yet to enter online, but may have it for you.
Computer manuals before 1970 or so are actually in demand and worth something (maybe $10-$25).
Tag lost or not installed.
Just shows you how little you know about manufacturing, new does not necessarily imply quality just like old doesn't mean it's of poor quality.
At the mill I worked at our oldest major piece of equipment is about 80 or 90 years old. No real reason to upgrade it, it does it's job. The area of the mill that I worked at, the machines were about 40 years old, controlled by a 10 year old VAX who communicated with even older PLCs to do the real-time work, and yet the steel we produce is among the highest quality in the world...
Any half-decent emulator will pay attention to cycle counts. It's one of the few things that distinguishes an emulator from a virtual machine. Take MAME for example - all the CPU emulation in there tracks cycles.
I think you're wrong:
Including Edsac. IBM Series 1, PDP-8/E, VAX, CP/M, Sinclair QL, Windows PC, Oric and other obsolete stuff. Lots of fun!
The way it basically works is that process is started, and an approximation of entire image is copied over to the other machine. After a minute or so on some images, more on machines with many resources, the machines are basically close in contents. When the delta between the machines is fairly small, execution on the first is stopped, and all changes comitted to the second. Commands in the pipeline are moved to the second machine and the machine unpaused.
On virtual machines with big resources it does take a solid minute or more to get things to that point, but the result is flawless everytime. Having a shared fast disk array really helps, FYI.
Check out http://emulation.net/ which provides a one-stop resource for emulation on Mac OS and Mac OS X. They list 35 different computer systems for which you can get emulators. Most of them appear to be free.
///, Atari 800, Atari ST, Baby (SSEM), Commodore Amiga, Commodore 64, Commodore VIC-20, CP/M, Edsac, IBM Series/1, Macintosh 68000, Memotech MTX512, MIPS R2000, MO5, MSX, Oric, PC-9801, PDP-8/E, SAM Coupé, Sinclair QL, Sinclair ZX81, Sinclair ZX-Spectrum, TI/99, TO8, TRS-80, TRS-80 Color Computer, VAX, Windows PC, X68000
Acorn Atom, Acorn BBC Micro, Amstrad CPC, Amstrad PCW, Apple I, Apple II, Apple
If you prefer game consoles you have 13 to choose from. ROMs are hard to come by but if you look hard enough you can find them. And there is a huge selection available.
Atari 2600, Atari 5200, Colecovision, Intellivision, Nintendo, Nintendo 64, Odyssey^2, PC-Engine/TurboGrafx-16, Sega Master System, Sega Genesis, Sony Playstation, Super Nintendo, Virtual Boy
If handheld units are more your speed, there are Mac-based emulators for 11 different varieties. I haven't tried any of these, but if MacMAME and the other console emulators are any guide, these should run at full speed and beyond.
Atari Lynx, Dreamcast VMU, Gameboy, Gameboy Advance, HP-48 Calculator, Magic Cap, Neo Geo Pocket, Palm, Sega Game Gear, TI Calculator, Wonderswan
-- thinkyhead software and media