J151 SC88PIO

1. Introduction

The SC88PIO is a powerful and expandable single-board computer, based on the Intel 80188 microprocessor. It is designed as a low-cost target CPU board for stand-alone applications, but it has enough processing power to act as the main CPU in a large control system. It uses the industry-standard STEbus, so a large range of peripheral boards are available.

The SC88PIO is a software-compatible development of the SC88 series of processor boards. Its new features include 28 lines of buffered I/O via an Arcom standard 50-way signal conditioning connector, 64K of battery-backed on-board RAM, and sockets for up to 256K of EPROM. As a general-purpose computer, it can be used for any application (given the right software) from word processing to process control. The SC88PIO is well suited for use as an intelligent I/O board, where the on-board parallel input and output must be monitored and serviced very quickly.

A lot of software has been written for the 8086 and 8088 microprocessors, which will run on the 80188. The 80188 is simply an 8088 with support peripherals integrated on-chip. Arcom have a machine-code monitor for the SC88PIO board, and with a disk-controller board and an SDRAM board it is possible to run Concurrent DOS, the multi-user multi-tasking operating system from Digital Research. Other software includes routines to allow programs written in the C language to be put into an EPROM and run on the SC88PIO without disks, and software to run the SC88PIO with a disk controller board as a stand-alone data logger producing PC-compatible disks.

The SCPC88 is code-compatible with standard PCs and the Arcom SCPC88. It is often used as a low cost target board for code developed on a PC.

PC support includes a download/terminal emulation package for C, assembler, and Arcom's own multi-tasking BASIC compiler. This package, running on the SC88PIO and PC, also supports CGA and high-speed SG84 graphics.

The STEbus interface is an important feature of the SC88PIO. The bus has been ratified by the IEEE (as IEEE 1000), and is designed as a processor- and manufacturer-independent, asynchronous, multiprocessing bus. The asynchronous nature of the bus means that the SC88PIO must wait until a slave board (memory or I/O) acknowledges a bus transfer, so that any speed of peripheral board can be accessed by any speed of CPU board. The multiprocessing ability lets several CPU boards run on the same bus. This is explained in greater detail later on.