Hacking the Commodore C128

Thread: Hacking the Commodore C128

  1. DJ Overdose's Avatar

    DJ Overdose said:

    Default Hacking the Commodore C128

    Found this artical while browsing this morning. Interesting stuff. I was always a Spectrum fanboy though...

    Guest Post: The Real Story of Hacking Together the Commodore C128

    December 9, 2013 by Bil Herd 121 Comments
    Behind the C-128 from a 1985 Ad

    The most popular computer ever sold to-date, the Commodore C-64, sold 27 Million units total back in the 1980’s. Little is left to show of those times, the 8-bit “retro” years when a young long-haired self-taught engineer could, through sheer chance and a fair amount of determination, sit down and design a computer from scratch using a mechanical pencil, a pile of data books, and a lot of paper.
    My name is Bil Herd and I was that long-haired, self-educated kid who lived and dreamed electronics and, with the passion of youth, found himself designing the Commodore C-128, the last of the 8-bit computers which somehow was able to include many firsts for home computing. The team I worked with had an opportunity to slam out one last 8 bit computer, providing we accepted the fact that whatever we did had to be completed in 5 months… in time for the 1985 Consumer Electronics Show (CES) in Las Vegas.
    We (Commodore) could do what no other computer company of the day could easily do; we made our own Integrated Circuits (ICs) and we owned the two powerhouse ICs of the day; the 6502 microprocessor and the VIC Video Display IC. This strength would result in a powerful computer but at a cost; the custom IC’s for the C-128 would not be ready for at least 3 of the 5 months, and in the case of one IC, it would actually be tricked into working in spite of itself.
    Before the CES show, before production, before the custom IC’s became available, there was no choice but to Hack in order to make the deadlines. And by Hack I mean we had to create emulator boards out of LS-TTL chips that could act like the big 48 pin custom VLSI chips that Commodore/MOS was known for .
    Commodore C-128, the last mass production 8 bit computer and first home computer with 40 and 80 column displays, dual processors, three operating systems, 128k memory via MMU and one heck of a door stop.

    To add to the fun, a couple of weeks later the marketing department in a state of delusional denial put out a press release guaranteeing 100% compatibility with the C64. We debated asking them how they (the Marketing Department) were going to accomplish such a lofty goal but instead settled for getting down to work ourselves.
    As the project progressed we realized that this most likely was going to be the final 8 bit system to come out of Commodore. We began shoving in as many features as could fit in a 5 month time frame. Before we were done we would have a dual processor, triple OS, dual monitor (40 and 80 column simultaneously) with the first home computer to break the 64k barrier. We started referring to the C128 as 9 pounds of poop in a 5 pound bag, we couldn’t quite get 10 pounds to fit. We also joked about turning out the lights on our way out the door as we knew that the 8-bit era was coming to a close.

    The C128 would require two brand new 40 pin custom chips; a Memory Management Unit (MMU), a Master Programmable Logic Array (PLA), and the venerable but scary VICII video core chip needed to be re-tooled. We also had the chip guys bond up a very special 48 pin version of the 6502 microprocessor and we decided to use Commodore’s newest 80 column chip which by itself almost caused us to miss CES. (But that’s a different story)
    The initial Commodore C128 with three months to go until CES. Five custom chips have yet to be completed, in the mean time “chip emulators” kept it running enough that the system software could be written.

    So here is where the need for some serious hacking comes in; we needed to start writing software (a whole new Rom Kernel and Monitor and a brand new version of Basic featuring structured commands), we needed to start the process of making PCB’s and we needed to start debugging the hardware and understanding the implications of trying to use 128k of DRAM (yes “k”, not m,g or t) which was a first, as well as the first MMU in a home computer. Along the way it turned into a dual processor system 6502/Z80, and simultaneous 40 column TV display and 80 column monitor. Home monitors didn’t really exist yet, we were kind of counting on having that done in time also, along with a new hard drive.
    Bottom of the prototype C128; Three months until CES and it takes lots of jumpers and chips stuck to the bottom to make it work.

    What we ended up doing was designing the first PCB to take either finished 40 pin dip chips or 40 pin emulator cables leading to emulator boards built of 74LS chips that when combined with some rather cranky PLA’s (The FPGA of the day) and delay lines and whatever else we could find, acted close enough to a custom chip that the programmers could continue working.
    The VIC Video Chip for the C128 could initially be emulated starting with a C64 VIC Chip and logic and delay lines.


    Our construction technique was to add to the PCB as much as we knew we needed for sure and then add jumpers to that as needed. The mainstay though in the 80’s was good old-fashioned wire-wrap, and so we proceeded to lay out a sacrificial main PCB and wire-wrap sub-assemblies to act like the custom chips that would hopefully arrive in a couple of months. (Looking at the bottom of the main PCB its hard to believe that in about 3 months we would start a production run of several million.)
    Example of wire-wrap construction, power is gridded on the bottom, ground on top. A good tech could do this in about 4-6 hours.

    C128 PLA emulator. The new PLA was going to be really powerful, to emulate we had to make a lot of concessions to fit in the available sizes. (But that size limit was about to change)



    This was just the beginning, ahead lay some fairly insane kludges that all had two things in common; We had to get any hack or fix done overnight while the managers were home sleeping and the end result had to work in million piece quantity.
    During the final push to CES we ate our holiday dinners out of aluminum foil in the hardware lab using the heat of disk drives to keep the food warm, and the bathroom sinks doubled as showers. My shoes became unwearable due to extended use and were discarded, only to have a mouse take up residence in the toe. (The first Commodore Mouse)
    We assembled units in the booth the night before the show, Commodore Business Machines (CBM) employees were tasked with hand carrying the 80 column chip which had almost been a show stopper. The programmer that had ported CPM was able to fix the last of 80 column bugs by editing raw data on the floppy.
    Commodore C128 Boot Screen on 40 Column



    As far as the product performance at the show we nailed it. Nothing failed, there were no “blue screen” moments, and the press was kind to us. Upon returning to work we struggled with how to ramp down after having been in the crucible for so many months. Showers were taken and eventually the slack-jawed expressions gave way to normal-jawed expression.
    We figured we had done the last big 8-bit computer, we knew one era was ending but we were also excited about the advent of the 16-bit Amiga even amid rumors of big layoffs in engineering. Without the drive of the founder, Jack Tramiel, CBM seemed to wander aimlessly canceling the next computer, the LCD Computer system amongst little to no marketing of main products. The feeling for me was as the days of Camelot had come to an end. The team slowly broke up without a new challenge to bind us together, I ended up working at a Trauma Center in New Jersey in my spare time as I had become somewhat addicted to adrenaline.

    The Easter Egg in the Commodore C128

    Bil Herd went on to develop high speed machine vision systems and designed the ultrasonic backup alarm commonly seen on new vehicles. For the last 20+ years Bil has been an entrepreneur and founded several small businesses. Bil keeps in touch with collectors and other fans of the old Commodore computers through his website c128.com and will soon be opening his new site, herdware.com which will feature open source and educational electronics kits.
    The C128 Engineering Team as seen in the Easter Egg image:

    Bil Herd: Designer & Hardware Lead
    Dave Haynie: Intricate timing, PLA Emulator and DRAM
    Frank Palaia: Z80 Integration and Ram Expansion
    Fred Bowen: Programmer and Software Lead- Kernal & Monitor
    Terry Ryan: Programmer- Basic V7 including structured language additions.
    Von Ertwine: Programmer- CPM
    The Commodore C128 was produced in 1985 and sold 5+Million units generating about about $1.5 Billion in revenue. The C128D with built-in disk drive was supposed to be released at the same time as the standalone unit but the C128D did not make it into production for a couple of years.


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    DJ OD
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  2. tombott's Avatar

    tombott said:

    Default Re: Hacking the Commodore C128

    I was a Spectrum kids as well, I remember the shit my mates used to have trying to load games on their C64's. Those tape drive were seriously shit.
    Hats off though, that was some proper engineering back then.
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  3. Zippeyrude's Avatar

    Zippeyrude said:

    Default Re: Hacking the Commodore C128

    i had a vic20

    hours of copying code from a mag only to find it didnt work
     
  4. TAR's Avatar

    TAR said:

    Default Re: Hacking the Commodore C128

    Specy for me too. Tape to tape copying. It was so much easier to copy games back then. I used to write the volume on the tape, to make sure it would load first time.
    TAR seems to be a decent bloke!
     
  5. koola2's Avatar

    koola2 said:

    Default Re: Hacking the Commodore C128

    Did you see Charlie Brooker's how video games changed the world, he mentioned Commodore vs Spectrum user agreed on one thing and that was BBC Micro users were basically posh idiots.
     
  6. Shotgunjim's Avatar

    Shotgunjim said:

    Default Re: Hacking the Commodore C128

    I saw that programme, it was really interesting ( and still had some games missing for me!)
     
  7. Soulassassin's Avatar

    Soulassassin said:

    Default Re: Hacking the Commodore C128

    20 odd games on one cassette, wrote on the label the volume and the counter position so you could fast forward to the right game.
    Happy days
     
  8. cloudy73's Avatar

    cloudy73 said:

    Default Re: Hacking the Commodore C128

    Copy via high speed dubbing tape to tape. Class.

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  9. MsDG's Avatar

    MsDG said:

    Default Re: Hacking the Commodore C128

    Unfortunately the C128 was a bit of a fail, mainly because it didn't work very well as a C64.

    This wasn't really the fault of Commodore because technically the C128 was 100% compatible with the C64 (as per Commodore coding regulations). The problem was that the software companies hadn't kept to spec when writing games for the C64. In an attempt to squeeze every little ounce of power and space, they had used all kinds of tricks (like using the C64 printer buffer etc). Anyway the upshot was that games like "Green Beret" and "Frankie goes to Hollywood" (how sad is I remember this without looking it up) just didn't work. So here we had a next generation C64 that didn't run all C64 games and had little to showcase and improvement in games. Most people kept with the C64 until the Amiga/ST hit the stores.
     
  10. big3card's Avatar

    big3card said:

    Default Re: Hacking the Commodore C128

    The Commodore and its logo takes me back to school when a clipper lighter was lit and held upside down until the wheel and guard were red hot .. this was then squeezed against a victims NECK leaving them branded with a Commodore logo lol ... good old school days !
     
  11. spraky's Avatar

    spraky said:

    Default Re: Hacking the Commodore C128

    Racking my brain since I saw this thread, re. a game on the C64 where this dude with a "diaper" on ran along and you had to make him duck or jump over spears and stuff, think there was pyramids in it ???
     
  12. DJ Overdose's Avatar

    DJ Overdose said:

    Default Re: Hacking the Commodore C128

    Jack The Nipper maybe.

    I remember doing that with a clipper lighter, we called it a smiley thorough. Never noticed the commodore resemblance!


    DJ OD
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  13. XBOX4LIFE's Avatar

    XBOX4LIFE said:

    Default Re: Hacking the Commodore C128

    Quote Originally Posted by spraky View Post
    Racking my brain since I saw this thread, re. a game on the C64 where this dude with a "diaper" on ran along and you had to make him duck or jump over spears and stuff, think there was pyramids in it ???
    Frak rings a bell, we modded the graphics on frak for the C64and rebadged it to say F**K, very immature add ons iirc but it's what really got me into computers might still have it somewhere lol
     
  14. spraky's Avatar

    spraky said:

    Default Re: Hacking the Commodore C128

    Just thought of it, it was "Aztec Warrior".