Intel iSBC 80/20 System
This is a new page covering the iSBC 80/20 Single Board Computer (SBC).
This board was introduced in 1976 provide OEMs with an SBC to begin building
systems and applications using the 8080 processor. It was used with additional
boards from Intel to expand memory and I/O capabilities.
iSBC-80/20 Single Board Computers:
iSBC 80/20 and 80/20-4 Single Board Computer Hardware Reference Manual Feb 79 9800317D
Additional boards to make a complete system:
iSBC 32/48/64K RAM Board Hardware Reference Manual Jan 79 9800488B
iSBC 202 Double-Density Floppy Disk Controller Hardware Reference Manual 77 9800420A
Monitor Source Code
Mon80p Ver 1.1 for iSBC 80/20 [1 Nov 1976]
iSBC 930 Monitor (MON830) for iSBC 80/30 Manual [24 Apr 78]
Port of iSBC 930 Monitor for iSBC 80/30 with Modified Commands 
These Intel SBCs would not run the Intel MDS OS nor the ISIS-II OS. It would require
special versions of these to run modified for the I/O port assignments. The boards
also required a modification to disable the onboard ROM and RAM. I took the queue
from the iSBC 80/24 board, which used one bit of one of the 8255s to disable ROM and
RAM. The ROM maps at address 0H which has to be RAM for any of the OSs to operate. The
RAM has to be disabled because it overlays external RAM, and the external RAM is the only
RAM available for DMA operations from the disk controller boards.
Last updated: 16 September 2017