back to article Holy Crap! Bloke finishes hand-built CPU project!

Have you ever seen an up-close view of how a computer processor works? If you're in the UK, you can head over to Cambridge and see the process firsthand, thanks to the work of Reg friend James Newman, who has finally finished constructing his 16-bit masterpiece, the Mega Processor. You may remember the story of James and his …

  1. trenchfoot

    "I have to find some kind of home for it at some point because I want mine back"

    Science museum really should be interested in this (if they're not I shall stop taking my kids there forthwith!) What an amazing thing to have done, well done indeed sir.

    1. Mayhem

      Very much so, especially if they put an old 16bit machine next to it for scale (Megadrive maybe?), and a modern system-on-a-chip under a magnifying glass at the end.

  2. Phil Endecott


    There is someone on the planet who is worse at tetris then me....

    But he's surely better at soldering!

    1. This post has been deleted by its author

  3. Anonymous Coward
    Anonymous Coward

    An incredible piece of work. Very impressive.

  4. JeffyPoooh


    We did it with a single NAND gate (made from twigs and moss), and a couple of tubes filled with mercury. Turing complete. As soon as we powered it up, it offered us a free upgrade to Windows 10.

    1. Mark 85

      Re: Bah...

      Moss? Mercury? We would have been happy to have had those. We had to make do with 3 day old dung and dehydrated dog pee. All we were offered was Vista. And were proud of it, too.

      1. FIA Silver badge

        Re: Bah...

        Vista? VISTA? Mr La-de-da with your fancy memory protection. YOU were lucky. WE used to dream of Vista; whilst hand whittling our 2 bit CPUs using nothing more than hope and the dog eared edge of a wordstar function key strip; and one of the bits was permanently zero due to Father selling it and replacing it with an 'oola 'oop in the hope we wouldn't notice. Upgrade (paid for, mind!) was Microsoft Plus! for Windows 95, with the pinball game removed and the theme permanently set to that horrid brown one.

        1. Doctor Syntax Silver badge

          Re: Bah...

          "hand whittling our 2 bit CPUs"

          2? You had 2????

          We just had an MK SPST found in a junk yard.

  5. ecofeco Silver badge

    Well done

    Well done. Very well done. A sincere congratulations.

  6. Mikel

    16 bits? Nicely done!

    I would have gone for 8. Lazy me.

    1. Yet Another Anonymous coward Silver badge

      Re: 16 bits? Nicely done!

      discrete 6502 4000 odd transistors and only a foot square

      1. Will Godfrey Silver badge

        Re: 16 bits? Nicely done!


        Not really the same thing at all. That one has a much simpler processor, and all done on a single inaccessible 4 layer PCB with surface mount components.

        1. Yet Another Anonymous coward Silver badge

          Re: 16 bits? Nicely done!

          Just thought the readers would be interested - I didn't expect the Spanish Inquisition......

          1. Anonymous Coward
            Anonymous Coward

            Re: 16 bits? Nicely done!

            NO-ONE EXPECTS the Spanish Inquisition

    2. Neil Barnes Silver badge

      Re: 16 bits? Nicely done!

      Indeed. I built a couple of 8-bitters, but (a) I used gates in little boxes with legs on, instead of those tripod thingies, and (b) 16 bits looked like a step too far (though it *would* have simplified some things!)

      A pint, sir.

  7. Anonymous Coward
    Anonymous Coward

    Do I need to change the motherboard if I want to upgrade? Not bad for a first effort but if someone does this with valves I'll be truly impressed!

    1. Prst. V.Jeltz Silver badge

      "Not bad for a first effort " ?

      Troll alert!

    2. Ken 16 Silver badge

      Hydraulic valves, I trust?

      Not thermionic. The world needs a CPU that doesn't rely on this new fangled electricity.

      1. Mike 125

        Re: Hydraulic valves, I trust?

        Babbage been there, done that, (in theory).

        1. Antron Argaiv Silver badge
          Thumb Up

          Re: Hydraulic valves, I trust?

          "Babbage been there, done that, (in theory)."

          And was the first to discover that, while drawing up the concept is relatively easy,

          actually building the thing's a lot harder than it looks

      2. Michael H.F. Wilkinson Silver badge

        Re: Hydraulic valves, I trust?

        Not thermionic. The world needs a CPU that doesn't rely on this new fangled electricity.

        Real valves? Just ask Hubert.

        And Igor, of course

      3. Tom 7

        Re: Hydraulic valves, I trust?

        Checkout the Z3 - relays. 1st turing complete machine.

        1. energystar

          5-10 Hz relays

          You could hear that Z3 Thing palpitating.

      4. herman Silver badge

        Re: Hydraulic valves, I trust?

        Hydraulic computers were used in the explosives industry for process control till the 1980s at least.

    3. TeeCee Gold badge

      ....if someone does this with valves I'll be truly impressed!

      Er, you have heard of Tommy Flowers and the Colossus?

      1. smartypants

        Not the same thing

        Amazing though the colossus is (especially when you go and visit and see it working), it's not a CPU. It was hard-wired to do a specific job.

        What I love about computers - and especially the CPU bit - is that they aren't hard-wired to do a specific job. They'll do whatever you can think of. (Well, within reason!)

        1. Mike 125

          Re: Not the same thing

          But Babbage dreamt of a mechanical same thing:


          The Analytical Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete.[5][6] In other words, the logical structure of the Analytical Engine was essentially the same as that which has dominated computer design in the electronic era.[3]

        2. Anonymous Coward
          Anonymous Coward

          Re: Not the same thing

          "Amazing though the colossus is (especially when you go and visit and see it working), it's not a CPU."

          Though this is true, there were early valve Turing-complete computers. I've lost it now but I did once have a Mullard computer valve catalogue.

          However, the first working computer I ever encountered had germanium transistors.

      2. energystar
        Paris Hilton

        Is there a movie about that?

        Would love to find that...

  8. energystar

    These are the things that separate Men from Mice.

    Congratulations, James.

  9. Disk0


    will it run Crysis...

    And all I ever built is a lightswitch. Thanks for making us all feel like tinkering knobheads.

    1. 9Rune5

      Re: But

      Do not fret Disk0 – it is not the size of your lightswitch that matters, but how you use it.

      Is that a wallet I see in your coat?

  10. allthecoolshortnamesweretaken

    "If you want to build your own then the key thing is to sort out exactly what you want to achieve (and why) as early on as possible," he said.

    That's very good advice for any project and the key to successful project management.

  11. martinusher Silver badge

    Bit Tedious

    Back when I was a graduate student in the mid-70s I landed a project that was to cobble together some bits of old processor -- a graphics processor, bits of CPU and some vintage core memory -- so that we could attach this graphics processor to a minicomputer (an Elliot 803). This technology was mainly RTL -- resistor/transistor logic, or the descrete stuff that is mentioned here (although the graphics processor itself had a rather neat diode array microprogram memory). What you end up with are racks containing numerous cards -- one card per register. It was a lot of wiring up. The sort of thing that would merit one or two lines of VHDL these days. The only 'visualization' came from connecting neon light drivers to each register bit -- this was common practice in computers of that era -- with a telephone key that controlled the clock (run/stop/step).

    Having done it once I don't think I'd bother to do it again. You end up with a lot of architectural compromises because of the electronics (like in this case you ran all memory accesses through the main processor's accumulator since you had to write the core after reading it, the accumulator doubling as the memory data holding register).

    1. Anonymous Coward
      Anonymous Coward

      Re: Bit Tedious

      An Eliot 803! We learned Algol on one of those at Uni (Kent) around 1968 and then when I got a job I had to learn Fortran on an ICL 1903a.

    2. Anonymous Coward
      Anonymous Coward

      Re: Bit Tedious

      "since you had to write the core after reading it, the accumulator doubling as the memory data holding register)."

      Ah, the days when you had instructions like dca (deposit and clear accumulator) because not having to rewrite the accumulator cores saved time! The "clear accumulator" was just the effect of a read without following write.

  12. David Glasgow

    He should call it The Peach

    An altogether more satisfying Reg headline would then arise.

  13. cantankerous swineherd

    I managed a crystal radio once.


    1. 0laf

      A crystal radio was the extent of my electronic construction also.

      I think this chap has earned a pint or two.

  14. m0rt

    "Congratulations, James. May your work live on for years to come."

    Tell me that wasn't deliberate?

    Either way, cpu James is Legend.

  15. AndrueC Silver badge

    Will it run Windows 10?

  16. ratfox

    "an area of about 10m"


  17. Hans Neeson-Bumpsadese Silver badge

    Exchange rate

    £40,000 (currently ~US$58,188)

    I think you'll be editing this article frequently throughout the course of the day

    1. Anonymous Coward
      Anonymous Coward

      Re: Exchange rate

      Why not just make it £1 ==== $1

      that seems to be where it is heading and many US companies use that already. Better buy that stuff now because soon it will be £1 === $0.50 in the corporate market.

      Gloting smile on my face as I have almost $2000 in crisp new $50's just waiting for the right moment to change them back. Looks like it won't be long now.

      As for the rest of the BREXIT, all I can say is that 'this ain't gonna end well'.

      PM Boris will soon be riding to the rescue (shudder)

      The statement welcoming this by Donald Trump should be enough to tell you that this is not going to end well.

    2. Anonymous Coward
      Anonymous Coward

      Re: Exchange rate

      £40,000 Currently $1.26

      1. Anonymous Coward
        Anonymous Coward

        Re: Exchange rate

        Could all be a bit academic really. Post-Brexit economy goes to s**t = no job = no wage. Zero pounds = $0 regardless of the exchange rate

  18. Ivor
    Thumb Up


    That's got to go into the science museum.

  19. Blitheringeejit

    I vote OUT for the Science Museum...

    ...and IN for the National Museum of Computing in Bletchley Park - surely?

    But pint either way, splendid work!

  20. Adrian Midgley 1

    Well done

    that man. A British eccentric.

    1. energystar

      A British eccentric.

      No Adrian. Is that thinking that have been taking British efforts to nowhere. It's a completed educative project [Plus use Manuals]. Not just an eccentricity.

  21. Lusty
    Thumb Up

    King of the nerds

    Honorary Phd surely?

  22. Bitman
    Thumb Up

    Well done, James - I knew you would get there in the end.

    Ah, I remember the happy days when hundreds & thousands of components and circuit boards kept turning up in our office at work!

    1. energystar


      That was a Working office.

  23. Rich 11 Silver badge

    Serves me right

    and are now integrated on an atomic scale for modern microprocessors.

    Being in a foul mood this morning, I was going to quibble that modern microprocessors aren't yet working at the truly atomic scale. However a quick scribble on the back of a ballot paper suggested that copper atoms sit about a quarter of a nanometre apart, so a 9nm fab process is as near as damn it atomic scale. Better than I could manage with a shaky hand after a night on the Guinness anyway.

    1. energystar

      The moment finally comes...

      When you can't extract anymore from those poor&exploited&simple(atoms).

  24. jzl

    I'd love to be excited about this

    It's very cool.

    But I'm so sad about the horrendous madness that is today that nothing seems good in the world.

  25. ben kendim

    Architecture? Instruction Set? Clock Rate?

    Come on Reg editors, you missed the most important details about the design...

    1. Hans Neeson-Bumpsadese Silver badge

      Re: Architecture? Instruction Set? Clock Rate?

      It's all on the website linked from the article.

      Clock rate is quite interesting. Yes, it has one, but the clock can also be ticked/advanced manually to allow you to watch logic executing at a human-observable rate.

      1. energystar

        Re: Architecture? Instruction Set? Clock Rate?

        Remembering my old Basic Casio just going slower, and slower as batteries discharging [but actual computing correct].

  26. Munchausen's proxy

    '"I have to find some kind of home for it at some point because I want mine back," Newman says'

    Will it fit out the door?

    1. energystar

      Universities should be fighting for this Work...

      But such a bad mood ambiance that starting to doubt.

  27. Antron Argaiv Silver badge
    Thumb Up

    Judging from the photos

    He's done quite a good job of presenting it as well. It's one thing to build a machine from logic gates, but quite another to present it so that non-engineers can understand what's going on. He really has excelled at accomplishing the second part.

    I particularly like the LEDs for each memory bit.

  28. Roger Kynaston

    Can we git it to be PM

    Sounds like it would make a better job of the current crop both just departed and future. Must have more processing power than a blonde mop.

    Excellent project though and I would vote for either Betchley or Science Museum.

    Beer because the builder definitely deserves one and I need lots tonight.

  29. hplasm


    It's von Newman architecture...?

    Beer for you also, Sir!

  30. E 2


    This is the level of technology Britain can look forward to after brexit and the break away of Scotland, Wals, and Nothern Ireland, bwhahahaha!

  31. A Ghost

    Oh the ecstacy

    of completing a project like this. Well done.

    My idea of heaven would be to take a pretty decent dose of MDMA and have someone give an intricate lecture on how exactly this thing works. 2-3 hours should do it.

    I have an exceedingly basic grasp of how a cpu actually works, but I'm sure if it was explained to me in such a way, in a heightened state of awareness, I would be able to grasp and understand to a much deeper level how these things work.

    Bit like those South Americans who give lectures in places where everyone has partaken of ayahuasca.

    Don't knock it till you tried it.

    Whatever happens, I at least hope this thing can get out into the real world and someone gets the true benefit of all this hard work. Perhaps it could be installed in a university, where someone who really understands this stuff could explain it to students.

    Some people pay 50 quid to go to a footy match or see a band. I'd pay 50 quid to sit down and be talked through exactly what is going on here.

    The MDMA would be a nice touch, but our civilization is not advanced enough yet to see the benefits of things like that. I remember reading that the cpu itself was actually conceived on LSD.

    We really haven't learned how to explore our own minds, let alone the universe. Sorry for the OT.

    Amazing achievement.

    I really hope this can be put to some good use. It really would make a magnificent teaching aid to those of us that want to understand this stuff, but it's not something you can learn by yourself. To have a model like this in front of you and have it stepped through, instruction by instruction kind of thing, would definitely help elucidate the subject. I'd relish something like that.

    Please don't let this be lost in a broom cupboard somewhere. Hopefully it finds a suitable and fitting home to expand people's minds and bring them joy.

    1. energystar

      Re: Oh the ecstacy

      Well, LSD tends to 'blend', 'integrate' formerly discrete concepts.

      On this side of the time slide... Curious would be to see you doing that. Because all of the World is looking at You People right now.

  32. elaar

    "" -> "Problem loading page"

    Is his webserver running off his new cpu?

  33. oldcoder

    Might have had an easier time with a PDP-8 type of architecture. A simpler instruction set (all 8 of them).

    1. Anonymous Coward
      Anonymous Coward


      "Might have had an easier time with a PDP-8 type of architecture. A simpler instruction set (all 8 of them)"

      Extremely elegant with exposed microarchitecture. Main disadvantage is that you can't execute out of ROM because a subroutine call requires the return address to be written at the start of the subroutine. The PDP-8 had a massive security vulnerability coded right in at the instruction level!

      1. oldcoder

        Re: PDP-8

        Actually not. It was completely standalone - and there were versions that could use ROM, though the early ones would copy the code from the ROM then run it as usual.

        True, no security against physical access though - the front panel switches gave absolute control.

        It also was pretty good after adding a MMU to expand memory from 4K (12 bit) works to 32K. Application code couldn't use all the instructions (I/O instructions caused a trap). It also had no direct connection to the internet.

        1. Anonymous Coward
          Anonymous Coward

          Re: PDP-8

          "Actually not. It was completely standalone - and there were versions that could use ROM, though the early ones would copy the code from the ROM then run it as usual."

          Could you actually point to what I wrote that was wrong? Are you saying that the original PDP-8 instruction set with its 8 basic opcodes didn't have the only subroutine call as JMS:

          "The contents of PC (a pointer to the next instruction) is stored in memory location P as a return address, and then control is transfered to the location following P. AC and LINK remain unchanged. There is no return instruction; this is done using an indirect jump through P."

          Then there's the Z bit:

          "When the Z bit of the instruction is zero, page zero addressing mode is used. This allows addressing of memory locations 0000 through 0177...

          When the Z bit of the instruction is one, current page addressing mode is used. This allows addressing of memory locations in the current page, as determined by the 5 most significant bits of the program counter (more accurately, the 5 most significant bits of the address of the location from which the instruction was fetched). All PDP-8 assemblers will generate current page mode when the addressed location is in the current page.

          Direct addressing of locations not on the current page is impossible, but some PDP-8 assemblers will automatically generate indirect references to off-page locations, storing the indirect word at the end of the current page. This usage is considered unsafe because indirection may change the memory field being referenced!"

          Although the architecture was eventually extended, the mode of operation of the original PDP-8 made operating from ROM extremely difficult - effectively only addresses 0-0177 could be used as general purpose RAM and other data and variables had to be stored in the same page as code.

          Like the "other" early microprocessor the RCA 1802, the PDP-8 eventually got microcoded call and return instructions. But they weren't there to begin with.

  34. Anonymous Coward
    Anonymous Coward

    Yes yes...

    But can it run Crysis? And is there an Android build for it yet?

  35. Number6

    If he installs it in a Ford Transit, would it be considered as a classic example of Van Newman architecture?

  36. Anonymous Coward
    Anonymous Coward

    The 6502 done in dis-integrated components.

    "A new dis-integrated circuit project to make a complete, working transistor-scale replica of the classic MOS 6502 microprocessor. We brought our work in progress to show off at the 2016 Bay Area Maker Faire!"

  37. Anonymous Coward
    Anonymous Coward

    Qudos extraordinary

    I applaud his perserverance and fortitude. (For those without the mental and physical resources, you can try it virtually here )

POST COMMENT House rules

Not a member of The Register? Create a new account here.

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon

Other stories you might like