The SCPC88 is an 8088 processor board which is the heart of a powerful and expandable PC compatible STEbus computer, combining the benefits of PC software and STEbus hardware. The vast library of PC software can now access the huge range of rugged STEbus peripherals from several manufacturers.
Users upgrading from a PC will already be familiar with the PC memory and IO maps, hence PC-compatible information is only briefly described here. This manual provides the circuit diagrams, STEbus interface, connectors and new information unique to this implementation of a PC environment.
The SCPC88 board set consists of four single-height Eurocards. These contain the main functions of the PC. This manual describes the SCPC88 processor board. This is the heart of the boardset, and contains the 8088 CPU (4.77 or 7.16 MHz, software selectable), 8087 maths coprocessor socket (8087 not included as standard, BIOS EPROM, user-EPROM socket, 256k dynamic RAM, the FE2010A custom IC to simulate the PC logic, and the STEbus interface.
The disk-controller board makes it possible to run PCDOS, or MSDOS. The disk operating systems allow the SCPC88 access to software for any application from word processing to plant control.
The graphic display card can emulate a range of the most popular graphics boards for the PC, in a variety of resolutions. The STEbus interface is an important feature of the SCPC88. The bus has been ratified by the IEEE (IEEE 1000 1987), and is designed as a processor and manufacturer-independent, asynchronous bus. The asynchronous nature of the bus means that a slave board (memory or I/O) must acknowledge commands by the SCPC88, which will wait until it does, so that any speed of peripheral board can be accessed by any speed of CPU board. The SCPC88 is designed to be the single bus master.