PDP-8
PDP-8
The PDP-8 didn't lower the price of computing — it broke the price floor. Launched March 22, 1965 at $18,500 — the first computer under $20,000 — Edson de Castro's 12-bit design descended from the lab-bench LINC via the PDP-5 and cost less than a new house. Over 50,000 PDP-8s and clones sold across a quarter-century and five generations of the line. The industry named a whole category after what it proved: the minicomputer.[1]
The minimalism was brutal and deliberate: the PDP-8 has effectively eight instructions (six memory ops plus IOT and OPR), 12-bit words, 4K of core — and it omitted common operations entirely so they'd have to be built from other instructions, which is why PDP-8 code is famously intricate. It didn't even have a stack or a multiply at first (multiply/divide was an optional EAE board). DEC kept shaving the price anyway: the serial-ALU PDP-8/S (1966) became the first computer under $10,000; later TTL models — the 8/I, /L, and the ubiquitous 8/E — became the lab bench standard; the last CMOS-8s shipped in 1979.[2]
The machine that invented a word
The PDP-8's deepest legacy is lexical: it made "computer" stop meaning room. The story goes that DEC marketed it to labs as a "small computer," and — in the apocryphal version — the name "minicomputer" stuck because the machine was short enough to sit under a lab bench in the era of the miniskirt. True or not, the category it named was real: the PDP-8 ran factories, telescopes, hospitals, and typesetters — the first computer ordinary organizations could just buy. Its successor lines branched two ways: the PDP-11 (deliberately incompatible, and a legend) and the curious PDP-12, which could run PDP-8 and LINC programs.[3]
Where it sits
Between the PDP-1 (which proved a computer could be small) and the PDP-11 (which perfected the form), the PDP-8 is the hinge where small became mass: the first computer a school, a lab, or a small business could own outright. DEC built its empire on it — and the industry learned that the money was in the little machines.
Check your understanding
- What made the PDP-8 the "first minicomputer"?
- How many instructions did it have — and what did it deliberately omit?
- What price barriers did it (and the 8/S) break?
- What was the PDP-12?
Show answers
1 — it was the first computer under $20,000 ($18,500, March 1965) and sold 50,000+ — small computers became a product class. 2 — effectively 8 instructions; it omitted operations like multiply and subtraction — you built them from others. 3 — first under $20K (8), then first under $10K (the serial-ALU 8/S, 1966). 4 — a dual-personality successor that could run both PDP-8 and LINC programs.
Footnotes
- ↑ PDP-8 and the bitsavers archive — the March 1965 launch, $18,500 price, 50,000+ units, and the LINC/PDP-5 lineage
- ↑ PDP-8 description — the eight-instruction design, the omitted operations, the sub-$10K 8/S, and the 1979 CMOS end
- ↑ PDP-8 — the minicomputer category, the PDP-12, and the PDP-11 succession