The SP ROM by Comprocsys Ltd was an add-on card for the ZX81 that provided 256 x 192 bitmapped graphics, reading and writing of EPROMs and communication with peripherals through a Zilog 8255 PIA chip. It could be used in conjunction with the Comprocsys ASZMIC ROM or without (via ZX81 BASIC commands).

Comprocsys External Card Advert

Comprocsys External Card Advert

I have created a disassembly of the SP ROM from a scanned printout of a disassembly I created from the ZX81 to an Epson Dot Matrix printer in 1985.

It is available as a .zip file here which contains the binary sp-rom.rom file as well as the .asm source file and an Xcode project file.

(.zip file updated 2016-08-17)

ZX81 SP ROM Disassembly Xcode Project

ZX81 SP ROM Disassembly Xcode Project

The original manual has been scanned and is available as a .PDF file here.

SP ROM User Manual

SP ROM User Manual

Original scanned printouts from 1985 disassembly are available as a series of searchable .PDF files here.

SP ROM Disassembly Scanned Printouts

SP ROM Disassembly Scanned Printouts

zasm assembler can be found here.

See article Assembling Z80 Assembler .zasm source files with BBEdit and Zasm Z80 Assembler below for more information.

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