CP/M was an early operating system for 8-bit computers. See Wikipedia's CP/M Entry for more information.

Since initial versions of the H8 and H89 computers had the lower 8k of memory space reserved for system ROM and RAM, a modification was required for the older systems called "ORG-0". This modification allowed the computer to remap the lower 8k to be user RAM by setting a special bit in an I/O port. Newer H89's had this functionality built-in. 

Known Versions from Heath Company:

  • CP/M 2.2.02 - Came on 2 floppy disks (Disk I and Disk II)
  • CP/M 2.2.03 - Came on 3 floppy disks (Disk I, Disk II, and Disk III)
  • CP/M 2.2.04 - Came on 4 floppy disks (Disk I, Disk II, Disk III, and Setup Disk)

From the Spring/Summer 1982 Heath catalog:

Industry standard CP/M Operating System

  • Over 200,000 microcomputer owners use CP/M
  • Provides common hardware interface with flexibility

Features: CP/M, Version 2.2.03, frees the user from having to understand the details of underlying hardware. It has fully dynamic named-file allocation, program and peripheral output control and random or sequential data access. Has two-pass assembler, general-purpose editor, advanced 8080 debugger, file dump and copy between devices, system generation/relocation and file size/disk usage displays. CP/M requires an H-8/H-19 or H/Z-89 computer system with a minimum of 48K bytes of RAM and one disk drive (two disk drives are highly recommended). H-8 systems also require HA-8-8 Extended Configuration Option or HA-8-6 Z-80 CPU Card.

HOS-8917-2, hard-sectored 5.25" disk, 5 pounds. ...... $150.00

HOS-8937-2, soft-sectored 5.25" disk, 5 pounds. ....... $150.00

HOS-8947-2, 8" disk for H-47, 5 pounds. ................... $150.00

HOS-8967-2, 8" disk for Z-67, 5 pounds. ................... $150.00

Known Versions from Magnolia Microsystems:

  • CP/M 2.23
  • CP/M 2.24
  • CP/M 3.0 - Came with their 128K memory board, which supports bank switching.

Other vendors:

  • Lifeboat Associates - CP/M 1.4 - This version worked with the early non-ORG-0 systems.
  • DG Electronics


Last Modified: Saturday, 06-Jun-2020 00:02:25 PDT

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This site is dedicated to preserving the history of the original Heathkit computers. They were initially release in 1977 and included the 8-bit H-8 and 16-bit H-11 systems. The H89 was released in 1979.