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A project log for STEbus 80188 (SC88)

80188 and dynamic RAM

keithKeith 05/02/2024 at 18:260 Comments

SC88A,B,D

Now 80188 users have a choice: you can use the SC88A, B or D with its massive on-board dynamic memory capacity, or the SC88T low-cost target board with its four static RAM/EPROM sockets.

Both boards are software compatible, using an 80188 processor which provides about twice the performance of a standard 8088. The 80188 has three counter/timers, two DMA controllers, an interrupt controller and programmable wait-state generation on-chip. Both boards have two RS232 serial ports with handshaking, using the powerful 8530 SCC at up to 1 Mbit/second.

Four STEbus non-vectored interrupts and two DMA Channels can be handled using the STEbus attention request lines. STEbus transfer errors can be detected using the 80188 non-maskable interrupt, and a programmable bus timeout circuit is implemented. The STEbus reset signal and system clock can be generated on-board.

A full range of software is available. There is an EPROM monitor with a comprehensive range of facilities, development support on IBM PCs and the powerful Concurrent DOS real-time multitasking multi-user operating system from Digital Research which can run and MSDOS programs. See the STEbus software datasheet for more details.

The SC88(A, B and D versions) is designed as the main CPU for powerful development systems. The SC88A has 64K of DRAM onboard, the SC88B has 128K and the SC88D has 256K. There is a socket for an EPROM of up to 32K. The on-board bus arbiter can operate in release-on-request and release-when-done mode, and the board can act as a default or a potential master. You can run Concurrent DOS with just this board and an SFDC floppy-disk controller.

Power consumption

1.3 A typical at 5 V, under 30 mA at ± 12 V

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