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 ExternalCard Advert 1

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 scaled 45pc Screen Shot 2015-06-05 at 4.07.28 pm

ZX81 SP ROM Disassembly Xcode Project

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

SP ROM User Manual scaled 45pc Screen Shot 2015-06-05 at 4.02.59 pm

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 Page 1 scaled 45pc cropped Screen Shot 2015-06-05 at 3.50.02 pm

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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