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Compu/Time -  SBC 880

This was a fairly straightforward Single board computer. Nicely laid out.

CompuTime SBC 880

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 operation.

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 front panel.

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 J2.
 
The manual for this board can be obtained here.

 

Other Compu/Time Boards
Clock/Calendar Board     FDC      SBC      256K RAM

 


This page was last modified on 10/25/2013