The PERQ Computer

Original Article ↗ Hacker News Discussion ↗

Emerging between Xerox’s Alto and Apple’s Lisa/Mac, the PERQ workstation exemplified an overlooked branch of early graphical computing: a microcoded, Pascal‑oriented “personal” machine with a high‑resolution bitmap display, mouse, and tiling window system. Commenters trace how its architecture (bitslice CPU, reprogrammable microcode, Q‑code), operating systems, and SPICE Lisp work fed into later technologies like Mach and CMUCL/SBCL, while contrasting it with contemporary Lisp machines, Xerox PARC systems, and Apple’s more commercially successful UI lineage. The exchange also highlights how rapidly UI ideas evolved in the late 1970s–80s and how much innovation arose outside Silicon Valley, in places like Pittsburgh and European research labs.

Role of PERQ in GUI and Workstation History

  • PERQ is highlighted as a lesser-known commercial system between Xerox Alto and Apple Lisa/Mac.
  • Commenters compare it to contemporary systems: Lilith, Lisp Machines, Xerox Interlisp-D, Smalltalk-80 workstations, and early Sun/HP machines.
  • Consensus: PERQ is more “in the timeline” than directly ancestral to Lisa/Mac; Apple drew much more directly from Xerox PARC’s work.

Hardware, Microcode, and P‑Code Debate

  • PERQ used a microcoded, bitslice CPU (e.g., 74S181 ALUs, Am2910 sequencer) with a writable control store.
  • It supported multiple microcode “personalities” and OSes; microcode was loaded at boot via a Z80 on the I/O board.
  • Disagreement over whether PERQ was truly a “Pascal machine”:
    • One side: native instruction set is a Pascal-style P‑code (Q‑code), so it’s effectively a P‑code machine.
    • Other side: microcode executes its own 48‑bit microinstructions and interprets P‑code; P‑code is only one of several supported instruction sets.
  • Both sides agree that user-writable microcode and fast bytecode interpretation were central design goals, and that “emulation vs native” is mostly a terminology issue.

GUI, Usability, and Applications

  • PERQ GUI is described as minimalist monochrome windows, fast on limited RAM and disk.
  • Some recall tiled window managers and mouse-driven environments; others note that screenshots don’t show later hallmarks like menu bars, standardized buttons, or desktops.
  • Broader context: early UIs (Smalltalk, Interlisp-D, Lisp Machines, Mac, HyperCard) differed greatly; “direct manipulation” as a formal concept only emerged in the early 1980s.

Software and Lisp Heritage

  • SPICE project on PERQ produced Spice Lisp, which evolved into CMU Common Lisp and then SBCL; Hemlock editor also originates here.
  • PERQ’s Accent OS influenced Mach, which later underpinned NeXT and then Mac OS X.
  • Discussion links these lines to broader language evolution (Mesa→Modula-2→Oberon/Modula-3, Smalltalk’s influence, etc.).

Geography and Industry Structure

  • Thread debates whether the 1970s computing industry was more geographically “inclusive.”
  • Some argue concentration in a few “champion cities” has grown; others counter with lists of recent hardware companies across many Chinese and global cities, claiming more geographic dispersion today.
  • No consensus; metrics for “inclusivity” deemed unclear.