It was the
beginning of a new year for Commodore Ltd. January of 1985 marked a full
year since Jack
Tramiel and the magic he brought with him had been gone from
Commodore, the Plus
/4, a computer that was to replace the aging
C-64
was a
flop. The people had spoken, they did not want a computer that was not
compatible with the C-64's vast library of software and peripherals. But
they did want advanced features that were on other computers such as the Apple
IIe, the IBM
PC, and it's clones and they wanted them at Commodore's usual affordable
prices. With this in mind, using the old
Tramiel philosophy, Commodore pulled another proverbial 'rabbit from the hat' and
introduced the Commodore 128 to the world at the winter CES
in January
1985. It
was everything the Commodorians were asking for and more. It had more
RAM
(128K expandable to 512K), it had an 80 column mode for word processing,
it had a faster floppy drive, it could even run CP/M without any ad-on
cards. It was completely compatible with the C-64
and it was priced under
$300.
The C-128 was in reality three computers built into one. This was achieved by
designing a motherboard around the new MOSTEK
8502 8 bit processor, capable of
emulating the older MOSTEK 6502/6510 processor, and the ZILOG Z80A 8 bit
processor allowing them both to co-exist on the same bus sharing resources
such as RAM and external peripherals. A remarkable achievement considering
the timing problems that had to be overcome with the C-64's 6510 processor
running at 1 MHz and the Z80A (which is an Intel 8080
clone) processor run at nearly two times that at 2 MHz. This all had to be incorporated into the same bus and output to the
same peripherals. Commodore engineers did a masterful job of
creating a computer capable of running the vast library of CP/M based
business software and easily switching to run the C-64
software complete
with all of its great graphics and sound capabilities.
In its native mode the
128 has most of the capabilities of both the C-64 and the Z80A machine. In
the C-128 mode it has access to 128K of RAM
that is expandable to 512K. It
also is capable of displaying 80 columns and the 1571
floppy drive is 7 to
10 ten times faster than the 1541. When the C-128 is in the
CP/M
mode the
1571 floppy drive is even faster running at up to 14 times the speed of
the 1541 and since the 1571 is a double sided drive it has more than twice
the storage capacity of its predecessor. Since the 128 uses the same VIC II 6564
video chip and SID 6581 sound chip it could access the C-64's graphic and sound capabilities
which allows the game writers to take advantage of the extra memory which
limited the C-64. Also exclusive to the C-128 mode is an extra 16K of
RAM dedicated to video chip, bringing the total on board RAM to 144K.
When the C-128 first boots
up you are greeted with an entirely new screen (see the above screen
shots) very much like the familiar dark blue on light blue of the C-64, only this one is
black on green. You will also
notice a newer version of BASIC
has been loaded. The display proudly
proclaims BASIC 7.0 is loaded and you have a whopping 122,365 bytes of
RAM to
work with. From this screen you can easily switch to the 64 mode
by typing GO 64 and pressing the RETURN button. After a brief delay
the familiar blue C-64 screen is displayed (see the above screen shots). The
C-128 in the C-64
mode is 100% compatible with all of the C-64 software and
hardware.
To accomplish this Commodore used the entire
C-64 KERNAL
and BASIC 2.0 ROM's unchanged, so when you
GO 64 you are in effect shutting
down the C-128 and turning on the C-64
instead of just running an emulation
of the C-64. Since the keyboard of the C-128 is some what different from
that of the C-64, only the keys that exist on the real C-64 are functional.
The keys across the top of the 128 are only enabled for the 128 or
CP/M modes. If the 1571 floppy drive is connected while you are in the C-64
mode it is automatically configured as the 1541 and will not read a double
sided disk. Also there is no command such as the GO 64 to return the computer to the C-128
mode short of turning the computer off and rebooting. This was necessary
to not make any changes to the original C-64 KERNAL to remain 100% compatible with the C-64 software and hardware.
The C-128 case design
is a radical change from the old boxy style of the C-64 or VIC-20.
Although still a one piece design it is now sleeker and cream colored, a
design that Commodore will use on all of its future one piece computers including
the repackaged C-64C. On the right side of the case are 2 - 9 pin
D-plug
ports for connecting input devices such as joysticks, light pens, or a
mouse. Next is a reset button and the off / on switch. Last is the power
supply port, a 4 pin square plug for the rather large 'brick' power pack
that supplies all the power for the computer.
There are 7 ports on the back
from left to right, the first is a parallel expansion port for cartridges
and special interfaces, next
is a cassette port for the VIC-1530
Datassette, next
is an 8 pin round DIN
plug for the serial devices such as the floppy drives and printers, followed by another 8 pin
DIN plug for a
40 column composite video output to a monitor like
the Commodore 1802, next is a slide switch for the channel 3 / 4
output selection and an RCA type plug for the RF output to a standard TV, next is a 9
pin D-plug for connecting to an RGBI (Red/Blue/Green/Intensity) monitor like the Commodore
1902, and
last is a user port for devices such as the Commodore modem.
The C-128 exhibited in
this museum was added to the museum on May 20, 1999. It was purchased
locally at a thrift shop.
