See all articles from Syntax/Syntax ZX80 v3 n7
Letters covering: FAST/SLOW mode switching in machine code monitors (Clark Calkins, answered by KO); expanding ZX81 on-board RAM to 2K using Fujitsu MB8416 static RAM (William Jordan); disabling SPACE-key interruption and CONT screen clearing (C. Alfred Spencer, answered by KO); explanation of Syntactic Sum meaning (Julian Goldman); Syntactic Sum FAST mode requirement and SAVE anomaly on ZX81 (Fred Nachbaur); working on SLOW mode add-on for MicroAce (Jason Harper).