2K Z80 Monitor Program for Microbyte MZ80A-IO

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S100 card
MZ80A-IO S100 CPU Card

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Initial Monitor Screen with The Command Summary Displayed

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Project Description

This program is a custom 2K eprom monitor routine that runs on a Z80 cpu card in the top 2K of memory space. This particular version runs on a Microbyte MZ80A-IO cpu card. It uses several pieces of hardware on other boards in the system. The system console uses the serial port (ports 2,3) on an IMSAI MIO serial/parallel/cassette tape board. Sample serial code is also included that accesses the 2 serial ports on the MZ80A-IO CPU card. A second big section of code is used for booting CPM from a parallel port interfaced SD card disk interface. Details will be revealed on another web page that is currently under construction. This parallel port micro SD card disk is interfaced through a port on the IMSAI MIO card. A 64K ram card with the top 2K disabled is used in the system for RAM.


CPU Board Summary

The MZ80A-IO is a complete single board S100 bus Z80A CPU with 2 serial ports (Z80A-DART) with switch selected baud rates from 50-19200 baud, 24 bits of parallel I/O (8255), an on board eprom socket for 2708, 2716 or 3732, 2 or 4MHz processor speed jumper, adjustable wait states and full vectored interrupt capability and 2 Z80A CTC counter timer chips. This board sold for between $280USD and $349USD in the early 1980's.
The original maufacturer contact information: Microbyte, 1198 E. Willow St., Signal Hill, CA 90806, (213)595-8571 (from Byte Magazine Feb 1981 page 149)
I have not been able to locate a schematic or user manual documentation for this board. Please contact me if you any further information.


System Requirements

The hardware setup:
- The Microbyte MZ80A-IO Z80 CPU card.
- Tanner 64K static ram card.
- The IMSAI MIO serial/parallel *2/ cassette interface card.(optional)
- The optional BUSMON card for debugging and blinking lights.(optional) s100-busmon project


Electrical Drawing(s)

MZ80A-IO Jumpers - mz80a-conf.pdf (45kB)
MZ80A-IO Parts - mz80a-parts.txt (3.4kB)
MZ80A-IO Partial Schematics - mz80a-multi.pdf (477kB)
Imsai MIO Jumpers - mio-jumpers.pdf (1.3MB)


Source Code

Z80 Source Code - MZ80A-IO.Z80 (42K)
Intel Hex Eprom Image - MZ80A-IO.HEX (5K)
The eprom image is burnt into a 2716 EPROM located on the MZ80A-IO CPU card.

The following 2 files are a standalone monitor that runs strictly on the MZ80A-IO card (does not support booting to CPM).
Z80 Source Code - MZ80MON.Z80 (32K)
Intel Hex Eprom Image - MZ80MON.HEX (4K)
Related hard disk emulation project supported by this monitor program
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