Heathkit H11
Personal computer released in 1978
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The Heathkit H11 Computer is an early kit-format personal computer introduced in 1978. It is essentially a Digital Equipment PDP-11 in a small-form-factor case, designed by Heathkit. The H11 is one of the first 16-bit personal computers, at a list price of US$1,295,[2] (equivalent to $6,392 in 2025) but it also requires at least a computer terminal and some form of storage to make it useful. It was too expensive for most Heathkit customers, and was discontinued in 1982.[3]
| Manufacturer | Heathkit |
|---|---|
| Type | Personal computer |
| Released | 1978 |
Introductory price | US$1295 (equivalent to $6,392 in 2025)[1] (kit) or US$1595 (equivalent to $7,873 in 2025)[1] (assembled)[2] |
| Discontinued | 1982[3] |
| Media | optional 8-inch floppy disks, optional paper tape |
| optional HT-11 | |
| CPU | LSI-11 clocked at 2.5 MHz |
| Memory | 4kword base system, maximum optional 32kword RAM, 8kword ROM (2 bytes/word) |
| Related | PDP-11 |
Background
The Heath Company, makers of electronic kits, announced its first two digital computers in 1977, including the H11 and less-expensive Heathkit H8. The company hoped that computers would soon provide more than 20% of revenue.[4]
Specifications
The H11 features:[5]
- Processor – LSI-11 (KD11-HA half-size or "double-height" card)
- Speed – 2.5 MHz
- ROM – 8 kWords (16 KB) (max)
- RAM – 32 kWords (64 KB) (max)
- Slots – 7 Q-bus slots
- Storage – H27 8-inch floppy drive (2 256 KB 8-inch single sided drives) or H10 paper tape
- I/O – serial (RS-232) or parallel ports
- Operating system – HT-11 (a simplified version of RT-11)[6]
- Instruction set – PDP-11/40 instruction set
- Languages – BASIC, Focal and others
H11 owners were eligible for DECUS membership, giving them access to that organization's library of software.[4] Initial memory limitations restrict the selection of system software, but the system RAM can be expanded to 32 kWords x 16 bit. Many PDP-11 operating systems and programs run without trouble. The system will also work with most DEC PDP-11 equipment, including many Q-bus compatible peripherals.
The H11 did not sell well. After discontinuation, a Heath/Zenith executive at a 1982 convention of Heath/Zenith owners told "a lonely H11 fan" that the new Zenith Z-100 "could run rings around the H11 ... The H11 is Sixties technology".[7]