| Products | Commodore 128, 128D, 128DCR, History, Manuals, Pictures & Time Line

By: Commodore  09-12-2011
Keywords: Cpu, Video Interface

The Commodore 128: The Most Versatile 8-Bit Computer Ever Made
by Ian Matthews of July 11 2003 - Revised Feb 25 2004

On this page:

This machine would be Commodores last 8-Bit computer; after this they would produce only 16/32 Bit Amiga's and IBM PC clones.

Bil Herd got the top job as 128 lead Engineer because of his vocal criticism of the new management teams lack of vision. "No one dreamed that C64 compatibility was possible so, no one thought along those lines. I had decided to make the next machine compatible with _something_ instead of yet another incompatible CBM machine. (I won't go into the "yes Virginia there is Compatibility" memo that I wrote that had the lawyers many years later still chuckling, suffice it to say I made some fairly brash statements regarding my opinion of product strategy) Consequently, I was allowed/forced to put my money where my mouth was and I took over the C128 project."

Commodore 128 Mode 2Mhz Speed (8502 CPU), 128K Memory, very nice 80x25 RGB display, advanced Basic 7.0
Commodore 64 Mode 1Mhz Speed (6510 emulation in the 8502 CPU), 99.8% compatible with 64 hardware and software, accessed by booting the machine while holding down the Commodore key or typing GO 64
Commodore CP/M Mode 1-4Mhz Speed (Zilog Z-80 CPU), 100% compatible with the huge volume of CP/M business applications such as Turbo Pascal and WordStar (an excellent program I used personally for years on a Sanyo!)  Note that the Z-80 processor was originally spec'd by Commodore management to be the same external expansion cartridge used on the C64.  However, to resolve several other engineering problems, Bil Herd designed the Z-80 into the main board.  This mode required CP/M software disks to be loaded on boot up.

All this would sell for an initial price of just $300; half of the Commodore 64 price when it was introduced two years earlier.

MOS 8502 CPU - Yet another derivative of the 6500 series
Zilog Z-80 Improved version of Intel 8080 CPU designed by the same Intel engineer
MOS 8563 CRCT / VDC - Video Display Chip 80 column x 25 rows 640x200 (128 mode only)
MOS 8564/6 VIC - Video Interface Chip (NTSC / PAL) - used in 40 column x 25 row
MOS 8722 MMU - Memory Management Unit
MOS 6581 SID - Sound Interface Chip
MOS 6528 CIA - Complex Interface Adaptors (2 of them!)

As if these problems were not enough, the power supply needed to be adjusted for each chip or they would literally burn up.  "No single custom chip was working completely as we went into December (1984) with the possible exception of the 8510 CPU..  At this point all I did have to lose was a HUGE jar of bad 8563's. (One night a sign in my handwriting "appeared" on this jar asking "Guess how many working 8563's there are in the jar and win a prize."  Of course if the number you guessed was a positive real number you were wrong.)"

Unbelievably, in this time of crisis, both MOS chip designers went on Christmas vacation and "..a sprinkler head busted and rained all over computer equipment stored in the hallway. Engineering gathered as a whole and watched on as a $100,000 worth of equipment became waterlogged..  I can honestly say that it didn't seriously occur to me that we wouldn't be ready for CES.. There were just too many problems to stop and think what if."

d out that Von, to make the 8563 work properly, was taking the little metal cup that came with his hot air popcorn popper (it was a buttercup to be exact) and would put an Ice cube in it and set it on the 8563.  He got about 1/2 hour of operation per cube. On our side there was talk of rigging cans of cold spray with foot switches for the CES show."

"We averaged 1-3 of these crises a day the last two weeks before CES.  Several of us suffered withdrawal symptoms if the pressure laxed for even a few minutes.  The contracted security guards accidentally started locking the door to one of the development labs during this time.  A hole accidentally appeared in the wall allowing you to reach through and unlock it.  They continued to lock it anyways even though the gaping hole stood silent witness to the ineffectiveness of trying to lock us out of our own lab during a critical design phase.  We admired this singleness of purpose and considered changing professions."

"Advertisements in the Las Vegas airport "The next day we meet up with the guy who developed CPM (Von) for the C128. As I mentioned earlier, someone forgot to tell him about the silly little ramifications of an 8563 bug.  His 'puter didn't do it as he had stopped upgrading 8563s on his development machine somewhere around Rev 4 and the problem appeared somewhere around Rev 6.  As Von didn't carry all the machinery to do a CPM rebuild to fix the bug in software, it looked like CPM might not be showable.  One third of the booth's design and advertising was based on showing CPM.  In TRUE Animal fashion Von sat down with a disk editor and found every occurrence of bad writes to the 8563 and hand patched them.  Bear in mind that CPM is stored with the bytes backwards in sectors that are stored themselves in reverse order. Also bear in mind that he could neither increase or decrease the number of instructions, he could only exchange them for different ones.  Did I mention hand calculating the new checksums for the sectors?  All this with a Disk Editor. I was impressed.""Everything else went pretty smooth, every (power) supply was adjusted at the last moment for best performance for that particular demo.  ..On the average, 2 almost working 8563's would appear each day, hand carried by people coming to Vegas. Another crisis, no problem, this was getting too easy."

  • a large supply of online information;

  • consumer awareness, which created demand, and;

  • telecommunication capacity and skills

all of which are were required to develop and commercialization the Internet.

On an amusing note, I have often been asked questions from non-Commodore collectors about a super-rare prototype called a Commodore 1280.  Of course this is simply a misreading of the Commodore 128D name. 

Today (in 2003), 128D models are highly sought after by collectors and enthusiasts, usually garnering more than triple what a standard 128 sells for.

The People:

Bil Herd explained his team as follows:

Bil Herd Original design and hardware team leader.
Dave Haynie Integration, timing analysis, and all those dirty jobs involving computer analysis which was something  totally new for CBM.
Frank Palaia One of three people in the world who honestly knows how to make a Z80 and a 6502 live peacefully with each other in a synchronous, dual video controller, time sliced, DRAM based system.
Fred Bowen Kernal and all system like things.  Dangerous when cornered.  Has been known to  brandish common sense when trapped.
Terry Ryan Brought structure to Basic and got in trouble for  it. Threatened with the loss of his job if he ever did anything that made as much sense again.  Has been know to use cynicism in ways that violate most Nuclear Ban Treaties.
Von Ertwine CPM.  Sacrificed his family's popcorn maker in the search of a better machine.
Dave DiOrio VIC chip mods and IC team leader.  Ruined the theory that most chip designers were from Pluto.
Victor MMU integration. Caused much dissention by being one of the nicest guys you'd ever meet.
Greg Berlin 1571 Disk Drive design.  Originator of Berlin-Speak. I think of Greg every night.  He separated my  shoulder in a friendly brawl in a bar parking lot and I still cant sleep on that side.
Dave Siracusa 1571 Software.  Aka "The Butcher"

"The names of the people who worked on the PCB layout can be found on the bottom of the PCB."


"The syntax refers to an inside joke where we supposedly gave our lives in an effort to get the FCC production board done in time, after being informed just the week before by a middle manager that all the work on the C128 must stop as this project has gone on far too long.  After the head of Engineering got back from his business trip and inquired as to why the C128 had been put on hold, the middle manger nimbly spoke expounding the virtues of getting right on the job immediately and someone else, _his_ boss perhaps, had made such an ill suited decision.  The bottom line was we lived in the PCB layout area for the next several days.  I slept there on an airmatress or was otherwise available 24 hours a day to answer any layout questions.  The computer room was so cold that the Egg Mcmuffins we bought the first day were still good 3 days later."

Before its demise in 1989, the Commodore 128 sold a respectable four million units but this number could have been dramatically larger.  Much like the Amiga to come, Commodore was incapable of promoting the C128 to the appropriate target markets.  128's were insanely inexpensive when compared feature for feature with its the competition of the day.  If Commodore had developed and pushed the D models to the small business market in 1986, the 128 could have been a serious contender in that space.


Italicized lines refer to key moments in history that are not Commodore related


  • January 15th - Commodores founder, visionary and CEO, Jack Tramiel quits Commodore with secret plans to buy the near bankrupt Atari
  • April - Commodore launches its first IBM clone, the Commodore PC, at the Hanover Fair in Germany
  • April - Commodore shows the Commodore Z8000 at the Hanover Fair in Germany
  • Mid-Summer - Commodore decides the Ted / 264 / 116 / Plus/4 Series will not sell as a replacement to the C64
  • September - Bil Herd appointed lead designer on C128 project in an effort to get a new machine ready for show at CES in Las Vegas, the 2nd week of January 1985
  • November - New chips are still not close to stable
  • December - Z-80 CPU incorporated into motherboard design - chip problems start getting resolved quickly


  • January - Serious design problems still exist but are being resolve daily
  • January - C128 prototypes completed at 2am just 4 hours before the trip to CES
  • January - Commodore's hotel rooms have been cancelled, possibly by their former boss turned competitor, Jack Tramiel
  • January - Prototypes shown at CES are unstable, going through two 8563 video chips per day, but the audience is unaware of this
  • Januray - Atari introduces the 130ST: 128KB RAM, 192KB ROM, 512 color graphics, MIDI interface, and mouse for $400.
  • January - Atari introduces the 520ST: 512KB RAM, 192KB ROM, 512 color graphics, MIDI interface, and mouse for $600.
  • June / July - C128 production begins and units are to sell for just $300
  • Commodore stops production of the 64 several times (presumably in favour of the much more powerful 128) but restarts it because of demand


  • Design of the 128D, business style case with neatly integrated 1571 floppy disk drive begins
  • Germany celebrates its 1,000,000 C64 with a Golden Jubilee version
  • June - In an effort to revitalize sales, Commodore releases a sleek new 128 like case, changes the name to 64C, and bundles it with GEOS


  • 128D's hit retail stores in Europe and North America  for about $500
  • February - Commodore announces the Amiga 500 and 2000
  • April - IBM and Microsoft announce Operating System/2 - OS/2.
  • June - Atari releases the Atari XE Game System, with 64KB RAM, supporting 256KB game cartridges
  • October - Microsoft ships Windows 2.0


  • Production of all 128 models stops
  • Total Commodore 128 sales are in the four million unit range
  • Intel introduces the 80486 microprocessor at Spring Comdex in Chicago. It integrates the 80386, 80387 math coprocessor, and adds a primary cache. It uses 1.2 million transistors. Initial price is US$900

Prototype Commodore 128D Plastic Cases

Top Center Drive

Side Drive
Inspiration for the Amiga chassis?

Top Right Side Drive

Maurice Randall.

Commodore 128 Retail Package

Hand Painted Commodore 128

Commodore 128D In an Office

Back of a 128D

128D Retail Box

Commodore 1571 Drive

Commodore 128 Credits

SYS 32800,123,45,6

Commodore 128 CP/M v3

Screen shot from a 1985 CP/M ROM. This ROM and the amazing WinVice emulator are available now on our Downloads page. Note that unless you use WinVice's WARP mode, CP/M may take about 2 minutes to load.

Commodore 128 80 Column Mode

Shows Basic 7

Commodore 128 40 Column Mode

Shows Basic 7

Commodore 128D Board Layout Explained

European 128D Plastic Case

With Carry Handle

Zilog Z-80 CPU DIPP Pinouts

Prices For Commodore 128D

Compute! November 1988

X10 Home Automation on a C128

January 1986

CMD Hard Disk Advertisment

512K Expansion Cartridge Advertisement

from Berkely Software, makers of GEOS
Compute April 1991

512K Expansion Cartridge

Dow Jones News Service

Compute! March 1985

Commodore 128 vs Apple IIc Advertisement

Commodore 128 Advertisement

Thanks for the Memory

Commodore 128 Advertisement

How to evolve a higher inteligence.

Compute! February 1986

Commodore vs Apple 1

Targeted at education and home markets

Commodore vs Apple 2

The information in this article was current at 06 Dec 2011

Keywords: Cpu, Video Interface

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