500 / 700
As mentioned on the page for the B128,
the CBM-II models were Commodore's last effort to
capture the business market with it's superior proprietary technology.
All the machines in this line are distinguished by the MOS 6509 processor,
Commodore BASIC 4.0 (like that found in the later
CBM/PET computers, the Commodore "SID" sound chip, IEEE-488 peripheral
compatibility, an RS232-C port, and 80 column text video capability.
Shown here is a early prototype 256k low profile CBM-II machine.
This computer is part the "low profile" CBM-II series, called such because
they feature a single integrated unit with a full business keyboard,
numeric keypad, and 12 function keys. Being a 256k version of the 610,
it stores 64K in bank 1 for BASIC code, and bank 2 for variables, but then adds
banks 3 and 4 for variable storage as well.
The model number of this machine is hard an ascertain, though
either CBM 500 or CBM 700 would probably be most correct. The
low serial number,
West German construction,
top-mounted power supply
point to its
very early construction. This computer was initially constructed as a 128K machine. The
second two banks of ram chips date
from 1984, two years after the other chips. However, the
CBM 700 EPROM chips
inside are of typical Commodore factory make, and are mounted on typical
Commodore factory make 28-24 pin adaptors. This suggests that the machine was
upgraded by Commodore itself, and sold during the great CBM-II series dump of '84.
Just in case it is useful for identification, here is the
assembly number of the motherboard
and another marking. The number stamped in
black reads "1983".
Statistics, features, and CBM 500/700 resources:
8088 daughterboard inc
Expandable to 256k internal, 704k external
700 line Kernal
CBM Basic 4.0
MOS 6545 CTRC
Monitor: 12" Monochrome display
80 columns, 25 rows
MOS 6581 SID
3 voice stereo synthesizer/digital sound capabilities
Male edge-connector IEEE-488 port
Male edge-connector CBM Datasette port
Female RS232 port
Female edge-connector CBM-II/PET-II expansion port
1 RCA audio port
Power and reset switches
Optional cable attachment with IEC serial ports.
Full-sized 102 key QWERTY
19 key numeric keypad!
4 direction cursor-pad
Personal Note:The CBM-II line are personally very
cool to me. I used to sit and
write little BASIC programs on these things, but they fell out of favor
as my collection grew, so now they are all boxed up. This machine,
whatever its model, came from an eBay