Design Your Very Own Microprocessor

LightJockey writes: "CircuitCellar has a great article on designing and building your own microprocessor using FPGAs and openly available processor designs, ranging from ARM and MIPS based to custom designs, and even a couple SPARC based chips, and also a really cool 'processor toaster,' start with a base processor design, and using a webpage to select upgraded components, it spits out the VHDL file you need to create it. Brings garage hackerdom up to a whole new level!"

Comments

Processor toaster?

[AlaskanUnderachiever]

That's nothing new. I've been toasting processors for years now. All you need is any AMD chip, a failed heat sink, and 30 seconds of Half Life.

Don't allow whoever designed emacs to get ahold ..

[linzeal]

The damn thing would incorporate circuitry for a garage door opener, a missile guidance system, and would have all 20 megs of emacs stored in microcode.

Amateur chip designers

[ObviousGuy]

Without training and experience in hardware design at the college level, it is doubtful that any amateur could come up with a design that improved on existing chip designs or create a fundamentally new design that would be of interest to chip companies.

The hope springs eternal, though.

Re:Amateur chip designers

[mrm677]

Designing a modern microprocessor can not be done by amateurs or a group of people with a B.S. degrees in electrical engineering. Sure, many of us have taken undergraduate architecture classes and maybe have designed a simple pipelined microprocessor in Mentor Graphics or VHDL/Verilog. Some of us maybe even implemented it with FPGAs.

However, anything close to being as complex as Intel/AMD chips requires an army of highly experienced architects/engineers with many of them having pHD's. Even the software design tools, such as Mentor, cost well over $100,000

Then building the chip is another beast requiring a fab facility in the order of $1 billion for any process with feature sizes smaller than 0.5.

Microprocessors are becoming so complex to design and build, that only a few companies are surviving. Sort of like the aircraft industry. There are only 2 remaining companies in this world that design and build 300+ passenger commercial aircraft (Boeing and Airbus). It is infeasible for a new competitor to arise because of the capital involved (unless of course it is nationally sponsored).

Re:Amateur chip designers

[svirre]

Sure you can outsource. Practically all design houses outsorce fabbing (current estimates indicate that you need a turnaround of approx $7 billion to justify your own fab)

As a small time operator no fab is going to talk to you however. You are going to go through a middleman (just as well since these often supply design services like P&R(Place and route) and synthesis, withouth these services you'll be looking at a investment at approx $200 000 in tools)

For a pure digital diesign you can then get away with a tool investment of $2-5000 for simulation.

For fabbing you should expect $20-50000 in expenses to ready your design for tape-out. The cost of the manufacture will depend of wether you are going for an engineering run of MPW (Multi Project Wafer). An MPW will cost you $10-100 000 depending on process sophistication and size and yield 10-200 chips. An engineering run requires a dedicated mask set which will cost $100-500 000. The engineering run itself is consisderably cheaper and the masks may be reused for manufacture.

If you are going to do any leading edge design you will however need to do your own synthesis and P&R. If you target 0.18um of better you propably are going to need som degree of physical synthesis capability ($100000 and up). Fo manufacture you will also need to prepare a test procedure (ATPG tools (Automatic Test Pattern Generator) check in at approx $100000)

Also remeber that all tools will usually require a maintenance fee of 10-20% annually of purchase price (pays for upgrades and support)

At last don't forget computer hardware to run your tools on. Linux suffices for most tools, but some will only run on Sun/HP workstations.

Re:Amateur chip designers

[Bobzibub]

Replace
'Microprocessor' with 'Operating System'
'Intel' with 'Microsoft'
'AMD' with 'Sun'
....
Read the above comment again. ; )


Building a chip in a fab would have to be a traditional commercial endevour. Agreed. Aren't Boeing and Airbus the only two airline manufacturers because they are subsidized and therefore others cannot compete? Cheers!

Re:Amateur chip designers

[MoneyT]

I could swear I read something about this being the reaction Steve & Steve got from people about home computers. Too complex to buid a useful computer, never be able to compete with the big guys. Guess they were wrong too.

Besides, I wouldn't be aiming to build a computer processor. I'd just wna tto build a processor that could process something.

Re:Amateur chip designers

[imnoteddy]

Prototyping can be done much cheaper through MOSIS. If you just want to play with a simple processor (say an 8 bit processor in the 0.5 micron process) you can get in the game for $5,900 US. If you want to play in a 32-bit world, but don't need the hottest process, big onboard cache, etc., consider $15,500 US for 40 parts in a 0.25 micron TSMC process.
In amy case, the real advantage to a roll-your-own processor is not to build a better general purpose processor better than P4/SPARC/ARM/MIPS/PPC but to create a special purpose processor that does the one thing you care most about very well.

Re:Amateur chip designers

[mav[LAG]]

I agree with most of your points but the ARM is an interesting counter-example. It was designed by four or five guys at Acorn Computers in the UK. They had just been told to sod off by Intel when they wanted to license the 8086 as a base design. It took about five man years of work - five guys working for just under a year - everything worked first time when plugged in (including all the IO and the peripherals), and they got around the manufacturing problem by licensing the design to OEMs who wanted to embed it. It was (and is) a joy to program for, has very low power consumption and is easily extensible.

In a supreme irony, Intel ended up licensing the ARM from Acorn RISC machines in the early 90s. Right now ARMs are everywhere - PDAs, cellphones, routers and switches. Now of course a 200Mhz ARM running in an iPAQ is a little less complex than a modern P4 with SSE 2 and all its other bells and whistles, but it's close. I think its encouraging that designing a successful microprocessor has been shown to be not solely the domain of giant corporations with billions of dollars in fabs and armies of PHD-wielding staff.

Re:Amateur chip designers

[raytracer]

Designing a modern microprocessor can not be done by amateurs or a group of people with a B.S. degrees in electrical engineering. Sure, many of us have taken undergraduate architecture classes and maybe have designed a simple pipelined microprocessor in Mentor Graphics or VHDL/Verilog. Some of us maybe even implemented it with FPGAs.

This is either irrelevant or just stupid, depending on how you look at it,

It is true that no amateurs are going to build their own 747 either, but there are no lack of people who build their own planes and gliders. Using FPGAsof modest cost, amateurs can implement processors which are perhaps 8 years back in the power curve. I don't know about you, but I found the computer that I owned 8 years ago to be quite a useful gadget. The ability to reprogram the core of your microprocessor to (say) add new instructions, peripherals and capabilities seems to be a cool one. As the FPGA industry moves forward, experimenters in this technology will also track Moore's law improvements. Yes, they will always be behind what billion dollar fabs can produce, but I fail to see why this is a problem for amateur chip designers.

Microprocessors are becoming so complex to design and build, that only a few companies are surviving. Sort of like the aircraft industry. There are only 2 remaining companies in this world that design and build 300+ passenger commercial aircraft (Boeing and Airbus). It is infeasible for a new competitor to arise because of the capital involved (unless of course it is nationally sponsored).

Again, so what? We were talking about amateur designs, not going into competition with Intel and AMD. I imagine that Linus heard similar arguments about the infeasibility of writing his own operating system.

Linus took the wide availability of inexpensive PC computers and leveraged those to create a new operating system. Amateur FPGA designers could try to leverage the availability of inexpensive FPGA chips to design their own processors. If you asked me the likelihood that anyone would be using them in a commercial environment a year from now, I'd say it was pretty low, but in a ten year time span....

Re:Amateur chip designers

[svirre]

I was assuming at least 0.35um.

These prices are however just for the fabrication, no?

If so you will still need to do synthesis and P&R.

Of cource your point about just dropping in a processor as beeing uninteresting is well taken. Indeed a CPU is a very inefficient piece of logic. Dropping CPUs in FPGAs seem to me as a particularly stupid thing to do.

The whole reason many want a CPU in a SoC product is that they want the flexibility to reconfigure the chip and update it's algorithms without having to fabricate a new device. On a FPGA you allready have the flexibility to update at any time at practically no cost, so on those you will want to forgo the CPU entirely and implement the algorithm completely in hardware.

Also since FPGAs generally are unable to reach high clockspeeds, the designer really need to paralellize his algorithm to achieve any kind of performance.

(We recently have done a SoC project which was to be prototyped in a FPGA which included a 16 bit single issue unpipelined RISC core. On a virtex II 3000-4 this achieved a speed of 18MHz max)

Re:Amateur chip designers

[mrm677]

Take a few more advanced architecture classes.

ISA's are mostly irrelevant in terms of performance potential (except for IA-64 which I will get to). Both AMD and Intel devote a (small) portion of their transistor budget to dynamically convert the CISC instructions into RISC-like "micro-ops". Thus the actual execution core of the AMD K7 and Intel P6 micro-architectures are very similar to say the MIPS R10000 core. Now if Intel and AMD had a decent ISA to begin with, they could devote those transistors (used to convert CISC to RISC) to things like bigger caches. Thus the performance penalty of using a lousy ISA is really not that much as evident by the success of Intel and AMD in raw computational power.

Your comment about "RISC chips are really not all that complex" is extremely ignorant and uneducated. Please tell me again that the MIPS R12000 core is "not all that complex" after studying about superscaler speculative out-of-order execution.

The IA-64 ISA really is different because it takes a radical approach to achieving instruction-level parallelism. It is very VLIW-like and contains many advanced features like "poison bits", register windows (not SPARC windows), software pipeline support, etc. Thus the parallelism is discovered by the compiler and can be expressed to the architecture unlike RISC and CISC ISAs which rely on the hardware to discover and provide parallelism (through OOO execution).

Re:Amateur chip designers

[kilrogg]

Then building the chip is another beast requiring a fab facility in the order of $1 billion for any process with feature sizes smaller than 0.5.

You don't need to build your own fab, there are fabs out there that will gladly build your IC for you, the most popular being TSMC. Many companies use external fabs (so called "fabless" semiconductor companies), including house hold names like Nvidia or ATI.

Mind you its still expensive as hell (0.25 ~ 1million US$ for your own mask set for an advanced process) which is why many amatures use FPGAs instead.

FPGAs

[zephc]

I attended an IEEE meeting at my school recently, and a guy from Xilinx presented and demoed FPGAs (their brand of course) and told us why we should use FPGAs for our signal processing needs. Of course, being an SE student, there were quite a few thngs that were over my head, but of course talking about the massive paralellism clicked with me, and of course hearing that one client of theirs had OC-768 signal processing within one FPGA chip, well, that was pretty damn cool. Also, being able to design your circuits with a nice GUI interface, rather than in VHDL or Verilog or whatever, looked pretty damn cool.

Re:FPGAs

[svirre]

Right. You do _not_ want to deped on the supplied xilinx software for synthesis. It's pretty much crap. Use Synplicity or Leonardo Spectrum (to be replaced with Precicion synthesis this summer) instead.

Also, you do most definetly not want to design your circuit graphically. The time you are going to use to draw a single state machine graphically, I will have designed the whole circuit. Graphical design tools are OK for the structural design phase (this is however a miniscule part of the whole process), otherwise they ar pretty much toys. The best digital hardware design tool availible is Emacs.

Once you have learnt hardware design, and understood the difference between a programming language and a hardware description language, VHDL is quite easy to deal with (I don't know much verilog, and from what I have see I don't want to deal with it. It's a verification hell)

/.ed allready

[Kizzle]

Since most articles are /.ed as soon as they are posted. I think a great feature for subscribers would be a mirror to each article that is hosted on slashdot.

Point of FPGA processors

[brejc8]

The whole point of having an FPGA implementation is to allow you to get the latest version of the processor with a patch debug or improvement. Imagine compiling the latest distribution down to your processor and off you go. If you want it to do something special then hack the code.
www.opencores.org has many processors allready. I made a MIPS R3000 with a cache and MMU etc with minimal knowledge of hardware design.

This type of thing needs to be outlawed.

[Anonymous Coward]

Only properly government licensed and monitored programmers and technical people should be allowed to work on such technology as the potential for using this technology to violate the DMCA exists. Anyone who disagrees with this is a terrorist.

GOD BLESS AMERICA

Re:This type of thing needs to be outlawed.

[Animats]

Use the processors you develop to circumvent the built in copy protection that the DMCA flunkies are trying to get put in VCRs, CD drives etc etc etc.

The scary thought is that the RIAA and the MPAA might try to outlaw private possession of FPGA design tools and burners for just that reason. If the "encrypted all the way to the monitor/speaker" concept ever takes hold, you'll need to build hardware to get unencrypted digital content out. And an FPGA is the only reasonable way to build one-off complex digital hardware.

Hate to say it, but this won't fly...

[redhatbox]

NOTE TO MODERATORS: Yeah, this is off-topic, but comes up often enough that I thought I'd take a stab at it anyhow. Thanks.

This would probably make a lot of people angry. Your motives are great; you want the subscriber base of /. to enjoy the articles, without having to brutally flood some guy's server(s).

Trouble is, a lot of sites look to ad revenue to pay for at least some of the cost of hosting and bandwidth. If you mirror the article, most ad systems are "cut out of the equation." Now, this is sounding better and better for /. readers, but not so hot for the site operators' bottom lines. Even if the server goes down, the revenue from our traffic may be well worth the downtime (depending on the site, of course).

Maybe mirroring of academic articles (without ads or other profit-generation methods) would be appropriate, though. Or, maybe /. could try to contact a site owner prior to posting an article. Say, give the owner a couple of hours advance notice, and let the guy decide for himself if he'd rather be mirrored or /.'ed.

Just a few thought. :)

Re:Don't allow whoever designed emacs to get ahold

[ActiveSX]

It's a Free fortress. Open fortresses are a different movement.

FPGA Fun

[CajunArson]

OK, you can reimplement a modern processor core in an
FPGA if you really want to (I can guarentee you that
the FPGA will NEVER run anywhere near as fast as the
regular chip) or you can do what I did for our senior
design project

We used a Xilinx Spartan II to run the main board on a model helicopter control. The idea was that several sensors, including a 2 axis tilt, accelerometers, RF controller and an ultrasonic sonar could be easily integrated into the VHDL core, and then the chip would calculate 4 PWM outputs that drove the 4 motors. While the thing unfortunately didn't fly (weight problems, but hey, we're CompE's not aeros!) the board itself worked
great and the software UART outputted all sorts of fun data about what was going on.

Here's the interesting kicker: The entire system was clocked at a grand total of 1MHz (that's right folks, 1Mhz) and even that was too fast for most of the onboard operations that we internally clock divided. This thing operated all of the components completely in parallel, so there were no interrupts needed at all. The reconfigurability of the FPGA means you can quickly adapt it to solve a whole bunch of specialized problems very efficiently and quickly. This thing definitely met the criterion for a hard realtime system (motor updates within 1ms of a sensor or RF input) and it did it all
via VHDL code, no OS or any high level software needed.

Now obviously this is a very embedded solution and is not extremely flexible, but sometimes you need to step back and look at the true advantages that the hardware provides for you, and use it for something other than reimplementing someone else's CPU core, (of course, that
can be a hell of alot of fun too.... mmm... 21st Century overclocked Trash 80)

PS--> use my spam address: foxcm2000@hotmail.com and
I'll be more than happy to send you all the VHDL we used
to implement the project since I just graduated yesterday! :)

Open Source Hardware

[Niscenus]

I had an article on this awhile back ago (toasted like AlaskanUnderachiever's previous four AMD's), but with the site now gone, I can't seem to find it in either google or wayback.

Anyhow, I think it is important that even hardware move over to the open source world. There are three requirements for this to kick off:

An inexpensive system for creating them

Knowledge and understanding of the standards involved

A central repository for updating and dissemination

If a common public utility for creating wafers could come out at fair cost (say, atleast equal to a computer, estimate $800 or so) that would be a major step for the first part. If the group involved at the IEEE for processor standards could freely distribute some or all of the necessary information, similar to as PARC did with POSIX, that would assist in the second. Finally, we would need a FreshMeat equivelant for hardware designs.

Processors are only a beginning...solid state technology, drives and cards would come fast thereafter. Is it an emerging field or something that will remain in the hands of the elite few who actually know the difference between a PSU and an FPU? I can wait you people out...I've been waiting out for the creation of massively distributed Open Source Software before many of you were born!