From the time I wire-wrapped my first 8085 3-chip system (8085, 8155, 8755) I was hooked on the 8085. Since then I have made many a circuit board but have never made a PCB of the 3-chip shown in the MCS-85 user manual. Decades later, while i have and use most of the Intel Multibus based single board computers (e.g., iSBC 80-05, iSBC 80-10B, etc.) but the urge to have a simple 8085 Single Board computer became strong enough that i decided to make my own version.
I wanted the SBC-85 to be very usable, i.e., enough RAM, enough ROM, a little I/O, and a serial interface to connect to a terminal program. Having these basics will make the board suitable for not only a powerful resident monitor, but would allow it to run a tiny basic or CP/M.
The SBC-85 has the following:
- 8085 CPU
- 8155 on a pin header for a ribbon cable (which provides 256 bytes of RAM, 22 bits of I/O, and an internal timer)
- 6264 8kByte RAM
- 2732 4K Socketed EPROM
- 2732 4K EPROM in ZIF socket
- MAX232 RS232 level shifter
- Expansion bus via a card edge
Using a regulated 5V power supply, a terminal or RS232 port, an EPROM programmer, and something to write code (like one of the 8085 assemblers) this makes for a great playing / learning platform for anyone at any level of familiarity with the 8085.
Download the SBC-85 v1.0 Documentation using the buttons below.