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Table of Contents
Z80SBCRC, Z80 single board computer for RC2014
Introduction
This project started off as a quicky prototype to check out whether the lot of Z80 I purchased off eBay really can run at 20MHz (yes, they can). Because it is simple and fast, it is ideal as a single board computer in the small RC2014 form factor.
Features
Z80 running at 20MHz
ROMless
Battery-backed 512K RAM
32 banks, each bank is 16KB
Simple serial port with serial bootstrap capability
Serial port operates at 115200 N81, no handshakes
Compact flash interface
CP/M 2.2 and CP/M 3
100mm x 50mm pc board
RC2014 bus interface
Functions
The heart of the SBC is a 5V CPLD, Altera EPM7128S, that implements the serial port, generates baud clock, interfaces to compact flash, and divides memory into 32 banks. The design has no ROM. The traditional ROM software are stored in battery-backed RAM. The serial bootstrap function loads the ROM-equivalent software into RAM when the board is powered up the first time; the system boots off the software in RAM for subsequent power cycles or resets. The ROM-equivalent software are protected by switching to banks inaccessible to normal software.