Daves Old Computers - Morrow Micro Decision

The Morrow Micro Decision MD series was George Morrows answer to the high cost of personal computers in the early 80's. All three models were Z80 based single board computers (no S-100 bus) with two serial ports, and an expansion drive connector for external drives. The Micro Decision ran the CP/M operating system.

One notable feature of the Micro Decision is that it has no fan, this along with the fact that the drives spin only when accessed means the machine runs with no audible noise.

There were three models of the MD series. The MD-1 came with a single 5.25" single sided disk drive. The MD-2 came with two 5.25" single-sided drives, and the MD-3 came with two 5.25" double sided drives.

Click any photo to view a large high-resolution image.

This is an MD-2 with the original SA-200 2/3 height single-sided disk drives. Also shown is the standard Morrow OEM ADM-20 terminal by Lear Siegler, making this machine the exact configuration shown in the Morrow advertisement and review posted here.

This is a Morrow MD-3. It is actually the same case and mainboard as the MD-2, only the drives have been replaced with two 1/2 height double sided drives, and a filler plate has been added to cover the other drive opening. Also note the front panel "badge" is changed. Also shown is a Morrow OEM Freedom-100 terminal by Liberty Electronics.

This is a Morrow MD-2 which has been upgraded to the equivalent of an MD-3 by replacing the single-sided Morrow diskette drives with a pair of Tandon TM-100-2 double sided drives. Also shown is another Morrow model MDT-60 terminal.

Closeup views of the front panels:
Bottom: Morrow MD-2 with original Morrow drives
Middle: Morrow MD-3
Top: Morrow MD-2 upgraded with Tandon drives.

Rear view, Left to Right:
Power connector & Switch, Expansion drive connector, Printer/Modem connector, Console terminal connector.

Inside the MD-3. On the left, we see the 5.25" drives. In the center, we can see part of the main logic board. On the right is the switching power supply. Beneath the supply is a ventilation grill opening to the bottom of the machine, allowing air to circulate through the supply and main cabinet by convection only.

Here are some of the original Morrow manuals.

And here are some of the original diskettes which came with the machines.

Micro Decision Questions and Answers (2.4M PDF)
Micro Decision User Guide (3.1M PDF)
Micro Decision Service Guide (1.5M PDF)
Micro Decision Rev2 Board Technical Supplment (280k PDF)
Micro Decision Schematic Drawings (2.2M ZIP/JPG)
Micro Decision 1983 advertisement. (250k JPG)
Micro Decision 1983 review. (400k PDF)
MDT20/ADM20 Technical Reference Manual (2.4M PDF)
Sugart SA-200 minifloppy OEM Manual (1.1M PDF)
CP/M version 2.2 Manual (500k PDF)
Z80 CPU Technical Manual (5M PDF)
Computer Users of the World Unite! Quotations by Chairman Morrow. (25k TXT)

Z80-CP/M emulator
Z80-CP/M simulator - boots CP/M

Back to Old Computers

Copyright 2004-2005 Dave Dunfield.