Memory map

A project log for ZX80 with 40 column text

40-column text, and square pixels mean 45 degree lines look right. Runs 13% faster as well!

keithKeith 09/23/2023 at 23:190 Comments

ZX81 BASIC, based on Shoulders of Giants improved code, hacked for operation at 7.375 MHz. 

Contains two versions, one with normal 32-column text, another with experimental 40-column text. 

This is a 32K ROM, use lower or upper 16K in the bottom 16K of the ZX80 memory map. 

Both versions include a 2K monitor at 3800 hex. 

0000 8K ZX BASIC
2000 2K blank (FF)
2800 2K G007 graphics
3000 2K blank (FF) 
3800 2K ZX81 monitor 
4000 As first 16K, but with alternative display width. 

 Connect the ROM A14 to a 1P2T switch, to select display width at reset. 

The G007 graphics does not work without the G007 hardware. I just put it there for later experiments.