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Sinclair QL

QL · 1984–1986 · desktop

Specifications

Cpu: Motorola 68008, 7.5 MHz (8-bit external data bus, 32-bit internal registers)
Ram: max: 128 KB on-board; expansion via the expansion port could add several hundred KB to a few MB depending on third-party add-on · base: 128 KB
Ports: RGB monitor output · UHF/RF TV output · 2x RS-232 serial · Expansion port (ROM cartridge / peripherals) · QL network (proprietary local network) port · 2x joystick ports · Microdrive cartridge slots (x2, built in)
Display: Two modes: 512x256 in 4 colors or 256x256 in 8 colors, via TV (UHF) or monitor output
Storage: base: Two built-in Sinclair Microdrive tape-loop cartridge drives (~100 KB per cartridge) · options: Third-party 3.5" floppy disk interfaces · Third-party hard disk interfaces via the expansion port
Os Support: latest: QDOS / SuperBASIC in ROM; later boards shipped Minerva, a bug-fixed community/third-party ROM replacement · shipped: QDOS (Sinclair's own operating system) with SuperBASIC in ROM
Release Price: £399

Variants

Models

Launch ROM (JS)Early units shipped with buggy JS-issue ROMs and were widely returned or later upgraded; a known rough launch.

Minerva ROMLater third-party replacement ROM fixing many QDOS bugs, popular as a retrofit.

Upgrade paths

RAM

Several hundred KB to a few MB via third-party expansion boards on the expansion port · 128 KB was soldered on the main board; all further memory came through the rear expansion port, not a simple socket upgrade.

~£100-£200 for period third-party RAM expansions

MODERATE

storage

3.5" floppy or hard disk via third-party interfaces, replacing the notoriously unreliable Microdrives · The built-in Microdrive tape loops were slow and failure-prone; most serious QL users moved to disk interfaces from Miracle Systems or similar.

~£100-£300 for a period floppy or hard disk interface

MODERATE

CPU

68008 remained the stock CPU; some enthusiasts fitted accelerator boards with faster 68000-family chips · Not an official upgrade path, third-party accelerator boards existed but required real hardware work and are rare today.

varies, enthusiast/collector market

HARD