4 ms·
Very good point! Didn't the ZX81 add a few things though? It had a CPU based video driver driven by interrupts IIRC so the screen didn't flash all the time when
by klelatti 4y ago
Very good point! Didn't the ZX81 add a few things though? It had a CPU based video driver driven by interrupts IIRC so the screen didn't flash all the time when it was working - very, very slow though.
- rwmj 4y agoI'm not entirely certain. I know you could upgrade the ZX80 by installing the "New ROM", and I believe that was basically just the ZX81 ROM. Not clear if that gave you everything in a ZX81 such as SLOW MODE (see other replies).
- klelatti 4y agoIIRC flicker free depends on NMI from the ULA eg see > The ULA contains a 6.5 MHz crystal oscillator and a frequency divider which generates horizontal sync pulses at the video output and NMI pulses on the NMI output. From https://8bit-museum.de/heimcomputer-2/sinclair/sinclair-scans/scans-zx81-video-display-system/ https://8bit-museum.de/heimcomputer-2/sinclair/sinclair-scan...