Task: Purchase and Use an ATR8000 for Booting the CP/M Operating System
Needed: ATR8000, Standard Shugart Floppy Drive and CP/M Disks or a Floppy Emulator, 34-Pin Connector
Time: 1-2 Hours
Introduction
There are several options for booting the CP/M operating system on your Atari 8-bit computer. I have previously posted about using FujiNet with the RunCPM emulator, the 1090XL expansion system, and the Indus GT disk drive with a 64KB RAM upgrade. All are great options for experiencing CP/M on the Atari.
The most expensive and difficult option is also the most authentic. The ATR8000 was one of the most interesting third-party peripherals created for the Atari 8-bit computers. Introduced by SWP Microcomputer Products in the early 1980s, the ATR8000 transformed an Atari computer into a CP/M business system by adding a Z80 processor, serial and parallel interfaces, and support for standard Shugart-compatible floppy disk drives. Essentially, the Atari served primarily as a keyboard terminal and display device while the ATR8000 handled CP/M execution and disk operations.
I picked up several ATR8000s over the years but never had a Shugart drive to test them. I read on AtariAge that a floppy drive emulator compatible with HFE files could boot CP/M so I decided to give it a try since I had purchased an HxC floppy emulator from Lotharek in 2024.
Instructions
I am reluctant to recommend buying an ATR8000 since they don’t show up for sale very often and, given their rarity, can fetch a pretty hefty price. The last ATR8000 I saw on eBay sold for $1000 in 2026. The last one I purchased was $400 back in 2019. The time before I paid $275. Note that the ATR8000 needs to be the 64K model to run CP/M. Some 16K models have been upgraded.
Here are the basic steps for getting CP/M booted using an HxC floppy emulator on an ATR8000.
- I recommend purchasing an HxC floppy emulator from Lotharek. These run about $100 for this model. Cheaper ones may be available on his site. You will need a 2MB or smaller SD card and a MicroUSB power cable for the 5Vs it needs. Download the CP/M HFE file (ATR_CPMB.HFE) from this thread on AtariAge. Put it on your FAT32 formatted SD card. Insert the SD card into the HxC.
- Download the Auto-Term software that serves as the terminal software on the Atari. The ATR file is a few posts down in this thread on AtariAge. You can use that to make a real floppy or put it on an SD card solution such as FujiNet. I happen to have an original SWP disk:
3. Now it is time to connect everything up. First connect your Atari computer to the ATR8000 COMPUTER IN port using an SIO cable. Second, connect an Atari floppy drive to the PERIPHERAL OUT port. Third, connect your HxC device or Shugart floppy drive to the FLOPPY DRIVE port on the left using a 34-pin ribbon cable. Note that the port on the HxC is a standard 34-pin connector while the ATR8000 requires a 34-pin edge connector. I had to buy an adaptor cable.
4. I found that the boot order is very important. Here is what worked for me consistently:
A. Power up the HxC, but leave the ribbon cable disconnected from ATR8000
B. Power the Atari disk drive (e.g. 810, 1050)
C. Power the ATR8000
D. Boot Auto-Term from the Atari disk drive or FujiNet
E. Plug the HxC ribbon cable into the ATR8000
F. At ATRMON prompt, enter B
That is it! If all goes well, you should have booted CP/M using the Atari as a dumb terminal.
Comments
I am very happy to have the ATR8000. Am still looking for a Shugart drive.
Here is the ATR8000 user’s manual.
Here is a product review from Antic magazine (1983).
You can also work with CP/M in 80-columns using a DT-80 cartridge.
Some have noted online that many of the ATR8000 CP/M disk images circulating online appear to be incomplete, corrupted, or converted improperly, especially older TeleDisk archives. I have not confirmed this so just FYI.
In addition to the Z80 CPU, SWP offered an 8088 coprocessor expansion option (the Co-Power-88) for turning your Atari into a DOS PC. I would love to have one of these! Below is an add for this from SWP:
