regarding the zx81 schematic, in the CPU IC, or IC3 there are two pins with the number 19, how does this work? I also noticed that pin 18 is missing, maybe its mislabeled. Does anyone have any info on this?
If it is mislabelled, then wich one is 18, and which one is 19?
schematic mistake?
-
1024MAK
- Posts: 5123
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: schematic mistake?
Your have found a labelling error! Well spotted 
IC3, Z80 CPU pins:-
18 is /HALT
19 is /MREQ
- Z80 CPU pin-out
- Z80 CPU pin-out.png (80.93 KiB) Viewed 1548 times
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: schematic mistake?
Ah thank you. Didnt know if i was just seeing things.