Heathkit H-11
The Heathkit H-11 was a 16-bit kit computer that was a DEC LSI-11 underneath. Heathkit didn't design the processor. They sourced the LSI-11 chipset from DEC and sold it in a Heathkit chassis, with the usual build-it-yourself approach. The result was effectively a PDP-11/03 in kit form, running the PDP-11 instruction set and the DEC operating systems RT-11 and RSX-11.
Introduced in 1977, the H-11 was Heathkit's bid to enter the 16-bit market, going up against the 8-bit Apple II, TRS-80, and Commodore PET. It was priced at $1,295 as a kit, or $1,695 assembled. That was notably cheaper than the $2,000 DEC charged for the LSI-11 in single quantities.
It came as a metal chassis with a backplane, power supply, and floppy drive(s), plus a front panel with toggle switches (including labeled HALT and BOOT switches) and LED indicators for each register. You supplied your own terminal, typically a VT-100 or Heathkit's own H-19, which connected through an RS-232C serial port. Standard memory was 8K of RAM and 8K of ROM, containing DEC's ODT-11 octal debugging monitor. It was expandable to 56K through four expansion slots on the LSI-11 (Q-bus) backplane. A parallel printer port was also included. The H-11 supported up to two 8-inch floppy disk drives, using the standard DEC floppy interface.
The H-11 was a commercial failure. The price of add-on equipment kept it from catching on, and so did the lack of software compared to the 8-bit competition. It was sold from 1977 to 1982. Today it's recognized as a historically significant machine, one of the first 16-bit personal computers, and it remains collectible for its rarity and its position as a DEC-designed, Heathkit-built hybrid.
Known Specifications
- CPU: DEC LSI-11 (KD11-F), 16-bit, PDP-11 instruction set
- RAM: 8K standard, expandable to 56K
- ROM: 8K, containing ODT-11 monitor/debugger
- Bus: LSI-11 (Q-bus), 8-slot backplane, 4 expansion slots
- I/O: RS-232C serial port, parallel printer port
- Storage: up to two 8-inch floppy drives (standard DEC floppy interface)
- OS: RT-11, RSX-11
- Price: $1,295 (kit), $1,695 (assembled)
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