Compu/Time - SBC 880
This was a fairly straightforward Single board computer.
Nicely laid out.
The on board EPROM could be addressed on any 1K or 2K boundary. A 1K by 8
static RAM may be used in place of the EPROM if desired. Power-on jump was
available directly to the EPROM (or RAM). The EPROM could optionally be used
in shadow mode to allow the full use of 64K or more of RAM. Devices that can
be used in the EPROM location (U23) were 2708, 2716 EPROMS or the 4118
static RAM. In addition to the EPROM, an additional IK of static ram was
provided and it could be located on any 1K boundary. If the EPROM was not
used and the static ram was used instead at the EPROM location, a total of
2K bytes of ram could be present on the board.
The board was equipped with a USART and an RS232 interface. The baud rate
was programmable by means of a programmable timer. All modem signals
required by terminal type equipment was provided for and terminal equipment
may be connected directly to the RS232 connector (J1). Reverse channel
capability was available for use with buffered type devices such as
printers. The reverse channel was occasionally needed as a busy or ready
indication from the connected device. It could sense things such as out of
paper or ribbon etc.
A 4MHz crystal provides all system timing and can be selected for 2 or 4 MHz
A DMA capability was provided as well as a means of having the MWRT signal
generated on the CPU board or elsewhere in the system under control of a
Two programmable timers were available for use by user programs. The timer
output and controls were available at the parallel I/O connector J2. A
parallel input and a parallel output port was available for use at connector
The manual for this board can be obtained
Other Compu/Time Boards
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