HDOS
| Company type | Operating system |
|---|---|
| Industry | Computer software |
| Founded | 1978 |
| Founder | Gordon Letwin |
| Products | HDOS operating system |
HDOS represents an early microcomputer operating system initially crafted for the Heathkit H8, and subsequently adapted for the Heathkit H89 and Zenith Z-89 models. The system was developed by Heath Company engineer Gordon Letwin, who later became a principal architect for Microsoft's OS/2. HDOS was bundled with essential system utilities, including an assembler. Its functionality was further enriched by a wide array of both commercial and freeware applications contributed by the Heath User Group (HUG).
A key advancement in HDOS 2.0 was the introduction of loadable device drivers, which facilitated device independence and allowed for system expansion. Device identifiers followed a style reminiscent of RSX-11 (for example, DK0:, DK1:), all managed through a unified driver file named DK.SYS. The operating system also incorporated RSX features such as utilizing the PIP command for file transfers and employing the EOT to signify file completion.
In line with Heath/Zenith’s transparent philosophy, the company made the source code for HDOS available alongside hardware schematics and component lists. The official part number assigned to this OS was HOS-1-SL (595–2466).
As an alternative choice, Heath/Zenith provided the widely used CP/M operating system. Despite being technically different, CP/M and HDOS were priced similarly and offered comparable capabilities. By 1981, CP/M had become the favored OS within the company, reflecting evolving market demands and strategic direction.
Commands
HDOS supports the following commands:
- BOOT
- BYE
- CAT
- COPY
- DATE
- DELETE
- DISMOUNT
- FLAGS
- HELP
- MOUNT
- ONECOPY
- PIP
- RENAME
- RUN
- SET
- STAT
- STATUS
- TYPE
- VER
Versions
- HDOS 1.0 – created in 1978 by J. Gordon Letwin
- HDOS 1.5 – developed by Gregg Chandler
- HDOS 1.6 – developed by Gregg Chandler
- HDOS 2.0 – launched in 1980, authored by Gregg Chandler, released into public domain in April 1988
- HDOS 3.0 – public domain release dated August 1986
- HDOS 3.02 – improved iteration by Richard Musgrave
See also
External links
- HeathDOS
- Michael A. Pechuria, Comparing Two Microcomputer Operating Systems: CP/M and HDOS. Communications of the ACM, March 1983, vol. 26, no. 3.
- Society of Eight-Bit Heathkit Computerists – Archival site providing source code listings in PDF format