The Commodore 128: The Most Versatile 8-Bit Computer Ever Made
by Ian Matthews of Commodore.ca
July 11 2003 - Revised June 12 2012
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Commodore 128 History:
the summer of 1984 Commodore
decided that they needed a replacement for the amazingly
successful C64. More accurately they decided that the
TED / 116 /
Plus/4 / 264 Series was a failure as a replacement for the C64.
This machine would be
Commodores last 8-Bit computer; after this
they would produce only 16/32 Bit Amiga's and IBM PC clones.
Customer reaction to Commodores failure to provide native
CP/M support in the C64 and
(much worse) their failure to provide C64
compatibility in the Plus/4
/ 264 Series
taught Commodore engineers
some hard lessons. Commodore's founder and visionary,
Jack Tramiel, had quit months earlier and the new management
team wanted to just forget the Plus/4 / 264 Series fiasco.
Fortunately, the engineers knew they needed to fulfill promises of
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."
Under managements guidance,
the first C128 concept machines
(pre-prototype) made no attempt at C64 compatibility. Bil
recalls, "I looked at the existing schematics once and then
started with a new design based on C64ness. The manager of the chip group
approached me and said they had a color version of the 6845 if I was
interested in using it would definitely be done in time having been worked
on already for a year and a half...... And so the story begins."
Commodore needed its next
computer to be a serious upgrade from the C64 if it was to successfully battle
its arch nemesis; It needed to keep Jack Tramiel's,
from being successful with their rumored new "ST"
1982, Commodore released the worlds
first multi-processor personal computer, called
SuperPET, but it was targeted only at the education and
scientific markets. The
Commodore 128 was to be the worlds first mass market multi-processor
computer. It would also have two video subsystems, one of which
would allow it to connect to
A reviewer from
Your Computer magazine wrote "The dowdy shoebox image of the
Commodore 64 has been replaced by a slim line beige console that any style-conscious
businessman should be pleased to have on his desk. A full size typewriter
style keyboard has 92 keys, that travel and locate well." The 128's 80 column display
mode would produce 640x200 which was better than the CGA mode that IBM
PC's could produce even in the early 1990's! This new an powerful machine
would act as three completely separate computers in one:
|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
||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.
||CPU - Yet
another derivative of the 6500 series
version of Intel 8080 CPU designed by the same Intel engineer
||CRCT / VDC
- Video Display Chip 80 column x 25 rows 640x200 (128 mode only)
Video Interface Chip (NTSC / PAL) - used in 40 column x 25 row
Memory Management Unit
Sound Interface Chip
Complex Interface Adaptors (2 of them!)
technically complex machine would present serious engineering and
marketing challenges to any company. Bil Herd recalls "It was
sometime in September (1984) when we got 8563 (new 40/80 column colour
video chip) Silicon, good enough to stick in a system. ...One concern we
had was it occasionally blew up.... big time.... turn over die and then
smell bad..... But then all of the C128 prototypes did that on a semi
regular basis as there wasn't really any custom silicon yet, just big
circuit boards plugged in where custom chips would later go... but you
can't wait for a system to be completed before starting software
development. When this problem still existed on Rev 4 we got
concerned. It was at this time that the single most scariest
statement came out of the IC Design section in charge of the '63.
This statement amounted to 'you'll always have some chance statistically
that any read or write cycle will fail due to (synchronicity)' ".
"Synchronicity problems occur when two devices run off of two separate
the VIC chip hence the rest of the system, runs off of a 14.318Mhz
and the 8563 runs off of a 16Mhz Oscillator. Now picture walking
revolving door with your arms full of packages and not looking up
launching yourself into the doorway. You may get through unscathed if
timing was accidentally just right, or you may fumble through losing
packages (synonymous to losing Data) in the process or if things
up some of the packages may make it through and you're left stranded
other side of the door (synonymous to a completely blown write cycle).
didn't realize that he meant was that since there's always a chance for
cycle to slip through, he didn't take even the most rudimentary
against bad synchronizing. ...As it turns out the 8563 instead of failing every 3 years
(VERY livable by Commodore standards) it failed about 3 times a
In addition the yield on these
video chips was about .001%.
Commodores chip division
Technologies could only get three or four working
the per run. "A run is a half-Lot at MOS and costs between
$120,000 to run. Pretty expensive couple of chips."
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
jar and win a prize." Of course if the number you guessed was a
real number you were wrong.)"
With only five or six weeks to go until the January Consumer
Electronics Show in Vegas "...finger pointing was in High swing, (the systems guys
have said they wanted WORKING silicon) with one department pitted
other, which was sad because the other hardworking chip designers had
preformed small miracles in getting their stuff done on time... ...Managers
started getting that look rabbits get in the headlights of onrushing
trucks, some started drinking, some reading poetry aloud and the
commonly seen doing both. Our favorite behavior was where they hid in
offices. It was rumored that the potted plant in the lobby was
in line for
one of the key middle management positions."
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."
was developing CP/M at home (consultant). Von had wisely chosen not to
try to follow all of the current Revs of the 8563, instead he latched
onto a somewhat working Rev4 and kept if for software development.
Later we would find
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."
Bil Herd stated that a number of "odd engineering fixes", often
conceived after consuming a few beer at the bar beside the MOS factory,
resulted in seemingly insurmountable problems
being quickly resolved. The most important of these 'fixes'
Z-80 CPU into the main board. In addition to resolving
several taxing electronic problems, it elevated the C128 into the
realm of the business computer.
"A True Miracle and was accompanied by the sound of Hell Freezing
Rabbit getting the Trix, and several instances of Cats and Dogs
sleeping together. This was the first time that making CES became a
near possibility. We laughed, we cried, we got drunk."
"We averaged 1-3 of these crises a day
the last two weeks before CES. Several of us suffered withdrawal
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."
"We finished getting ready for CES about 2:00am in the morning of the day
were to leave at 6:00am."
"Advertisements in the Las Vegas airport and again on a
billboard enroute from
the airport inform us that the C128 has craftily been designed to be
expandable to 512K. Now it had been designed to be expandable
had been respecified by management so as to not be expandable in case
year's computer needed the expendability as the "New" reason to buy a
Commodore computer. That's like not putting brakes on this years model
so that next year you can tote the New model as reducing those
"Upon arriving at the hotel we find that out hotel reservations have
canceled by someone who fits the description of an Atari employee.
things occur in rapid succession. First I find the nearest
person owning a
credit card and briskly escort her to the desk were I rented a room
available days, second, a phone call is placed to another nearby hotel
canceling the room reservations for
Tramiel and company, third,
of those C64's with built in monitors (C64DX's??? man it's been too
brought out and left laying around the hotel shift supervisors path
accompanied by statements such as "My my, who left this nifty computer
here... I'd bet they wouldn't miss it too much".
"The next day we meet up with the guy who developed CPM (Von) for the
As I mentioned earlier, someone forgot to tell him about the silly
ramifications of an 8563 bug. His 'puter didn't do it as he had
upgrading 8563s on his development machine somewhere around Rev 4 and
problem appeared somewhere around Rev 6. As Von didn't carry all
machinery to do a CPM rebuild to fix the bug in software, it looked
might not be showable. One third of the booth's design and
based on showing CPM. In TRUE Animal fashion Von sat down with a
and found every occurrence of bad writes to the 8563 and hand patched
Bear in mind that CPM is stored with the bytes backwards in sectors
stored themselves in reverse order. Also bear in mind that he could
increase or decrease the number of instructions, he could only
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
getting too easy."
Commodore did not produce many peripherals
designed exclusively for the 128 line. Instead they relied
primarily on C64 devices like the 1541 floppy drive. An
exception was the Commodore 1902 monitor for
$400 ($100 more than the price of a new C128!) which was required to use the
new 128's advanced 80 column mode. The C1750 massive 512K RAM
Expander was another new product. The most anticipated new peripheral was
the 1571 double sided floppy drive which, at 360K, provided more than
double the capacity of the 1541. Much more importantly it was a
whopping 7 to 10 times faster!
Many Bulletin Board Systems (BBS's - pre-internet for those of you who
were born after 1980) also jumped on the C128 Mode bandwagon.
There are a number of historians who site Commodore as the unsung
development partner of the Internet. While it is certainly true
that the US military and several universities developed
transition into the internet would not have been so rapid had online
communities not been created with extensive use of Commodore hardware:
the amazingly inexpensive VIC Modem (and its decedents the 1600,
1650, 1670 and 1680) combined with powerful C128 Mode functionality
allowed thousands of BBS' to spring up from nothing. The 128
a large supply of online information;
consumer awareness, which created demand,
telecommunication capacity and skills
all of which are were required to develop
and commercialization the Internet.
Commodore 128D: In
an effort to extend the life of this powerful multitalented machine,
Commodore introduced a slight derivative of the 128 called the
Commodore 128D in 1987. The idea was to make a cleaner, smaller
foot print for the 128 so that it might appeal to
the small business segment dominated by IBM at the time. Commodore 128D models looked allot
like Apple Mac computers of the late 1990's. They came in a square desktop
box, featuring an integrated a front loading Commodore 1571 5.14"
high capacity floppy disk drive, and a separate keyboard. A monitor
could sit nicely on top of this chassis, again reducing desk space
requirements and clutter. The price of this system, just $500, a
third the price of an IBM PC.
In a cost saving effort, D's were
manufactured with less expensive "upgrade" versions of the SID (sound)
called the 8580 SID and were sometimes referred to a 128DCR's (Cost
The first European 128D's chassis were made of plastic. They
came with a keyboard dock and carry handle! The North American
model came in standard beige steel chassis' without the carry handle
or keyboard dock.
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
People: Early in the
process, a team of experienced hardware and software engineers were
assembled and they left their personal mark on the their machine with
an "easter egg". Type SYS 32800,123,45,6 on your 128
and you will see a small list of development credits. Note the spelling of the
word Hardware; presumably a tribute to Bil Herd. The image on
the left was created with the amazing
emulator available for download from
Bil Herd explained his team as
||Original design and
hardware team leader.
analysis, and all those dirty jobs involving computer analysis which
was something totally new for CBM.
||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.
||Kernal and all system
like things. Dangerous when cornered. Has been known to
brandish common sense when trapped.
||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
his family's popcorn maker in the search of a better machine.
||VIC chip mods and IC
team leader. Ruined the theory that most chip designers were
||MMU integration. Caused
much dissention by being one of the nicest guys you'd ever meet.
||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.
||1571 Software. Aka
"The names of the people
who worked on the PCB layout can be found on the bottom of the PCB."
"RIP: HERD, FISH, RUBINO"
"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."
the End: The 128 went on
to be a notable success for Commodore but not because of its new power.
Unfortunately most software developers ignored the new and advanced C128
Mode functionality. Why develop software for a new, relatively small
product like 128's native mode when you can write software for the wildly
successful C64 and
know that your code will function on a 128 operating in 64 mode. There were some notable
exceptions, such as the Graphical User Environment called
which created a powerful 128 Mode version.
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.
The last gasp was a very small production
run Commodore 128CR's (Cost Reduced) released in North America in 1988
or 1989. They were identical to the 128DCR except they did not
have an integrated floppy drive. I have never seen one of these
units... not even a picture! If you have one, please
email a picture to us and we will add it to this site with credit
On a sad note, the 128's CP/M
Mode was almost never used because CP/M was quickly losing ground to
Microsoft Disk Operating System (MS DOS) by then running at version 2.
MS-DOS was of course popularized by the
IBM PC and seemingly endless
line of IBM clone machines. Business developers had all but
abandoned the old standby CP/M in favour of the new and rapidly
expanding DOS market. The Commodore 128 was CP/M's last big
play, but the 128 just did not have the market penetration to keep
128 Reference Materials:
C128 Magazine Articles
Commodore 128 Announcement TPUG February 1985
128: What is the "Stack" Transactor September 1985
Commodore 128 Initial Review COMPUTE! June 1985
Cross a Commodore 64 with a CP/M
Business Machine & A New 128K Micro
Your Computer June 1985
CP/M: What is it?
Compute March 1985
Commodore 128 Announcement
Commodore 128 Special Bundle
Commodore 128 System Guide - Complete with Graphics and Basic 7, CP/M
Commodore 64 & 128 Tips Sheet - Hardware Failures - 1989
C128 / C64 Tips From June 1987 Calgary Commodore Users Group
Commodore Users Group 1987
BBS Software - (Not on this site)
Commodore 128 Chronology:
Italicized lines refer to key moments
in history that are not Commodore related
- January 13th - Commodore shows off
and 364 at CES and indicates they should be in production by June
- 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
- December - Z-80 CPU incorporated into
motherboard design - chip problems start getting resolved quickly
- December - A 16K version of the 264
Commodore 116 is for sale (at least in Germany)
Intel introduces the
80186, 80188, and 80286 processors
Motorola unveils its
68010 CPU chip
- January - The last
rolls off the line and into the history books
- 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
- 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
- April -
IBM stops production
of the IBM PCjr
- May -
Microsoft Windows 1.0 at Spring Comdex. Release date is set for June,
at a price of US$95
- September -
Apple Computer co-founder Steve
Jobs resigns from Apple Computer and founds
- Commodore stops production of the 64
several times (presumably in favour of the much more powerful 128) but
restarts it because of demand
- January -
starts producing the Macintosh Plus, with 1 MB RAM, support for hard
drives, a new keyboard with cursor keys and numeric keypad, for
- 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
- March -
goes on the stock market at $21 per share. This raises $61 million.
- 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
- August -
Intel ships the
- September - Plus/4 was in
full liquidation were selling for a mere $79
- September -
IBM announces the
IBM PC-XT Model 286, 640KB, 20MB hard drive, 1.2MB floppy,
serial/parallel ports, and keyboard for the low low price of $4000
- 128D's hit retail stores in Europe and North America for
- 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
- 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
Commodore 128 Picture
128D Plastic Cases
Inspiration for the Amiga chassis?
Top Right Side Drive
Images courtesy of Bo
Zimmerman and his amazing zimmers.net
Commodore site THANX BO!.
Original source for these graphics was
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
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
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
NOTE: commodore.ca would like to thank Bil
Herd and C= Hacking,
[email protected] and others, which were very
helpful in providing information and / or graphics for this page :-)