chromatics CGC 7900 Serial Port Controller May82 free download

File name CGC_7900_Serial_Port_Controller_May82.pdf

SERIAL PORT CONTROLLER MANUAL CGC 7900 SERIES COLOR GRAPHICS COMPUTERS CHROMATICS CGC 7900 Series Serial Port Controller Application Guide CHROMATICS CGC 7900 SERIES COLOR GRAPHICS COMPUTER SYSTEM SERIAL PORT CONTROLLER (SPC) APPLICATION GUIDE Copyright (c) 1982 by Chromatics, Inc. 2558 Mountain Industrial Boulevard Tucker, Georgia 30084 Phone (404) 493-7000 TWX 810-766-8099 May, 1982 Serial Port Controller Application Guide Page 1 IRTRoDUcrmH This Application Guide describes the Serial Port Controller, or SPC, an optional card in Chromatics', CGC 7900 series. The SPC is designed to handle low-level data communications chores in the 7900 system, for up to 4 RS-232 ports. By relieving the main CPU of the burden of handshaking and buffering, the SPC can greatly enhance system throughput. The SPC contains its own Z80 processor, and firmware which runs the normal "read character, write character" operations. This Application Guide is intended for the user who wants to customize SPC firmware for special purposes. We will discuss the SPC architecture, and provide programming examples. This document is written tor the experienced prograuaer. The SPC firmware is written in Z80 assembly language, and you will need access to a Z80 assembler and development system, or a compiler capable of generating Z80 code. For high-speed applicatiOns, running one or more ports at high baud rates, you will probably' have to write the majority of the firmware directly in assembly language for efficiency. Current SPC firmware was developed on Chromatics' CG series color graphic computer systems. We will begin by describing the SPC, its architecture, and how it operates in a standard CGC 7900 system. From there, we will proceed to the advanced features of the hardware, including some which are not normally used (but are installed). These features include the ability to run one or more ports with external clocks; daisy-chaining up to four SPC boards in a system; and interrupt-driven I/O. Other CGC 7900 documentation available from Chromatics includes the CGC 7900 User's Manual, OEM Manual, and Disk Operating System Manual. Additional SPC documentation includes the circuit descriptions, test procedures, schematiCS, and source listing for the firmware. Some of this documentation is considered proprietary, and you may be required to file a non-disclosure agreement. Page 2 Chromatics CGC 7900 Series Serial Port Controller Application Guide Page 3 ARCHITECTURE The SPC consists of a Z80 processor running at 2.5 MHz, two 2532-type EPROMs for onboard firmware (up to 8K bytes), 4K bytes of onboard RAM, and 1K bytes of two-port RAM.