ROM upgrade
ROM upgrade
I see the ROM upgrade for ZX80 is a change from 4K to 8K but both are in a 24 pin package. Classically 8K x 8 chips are in a 28 pin package. How is this, or better what have I misunderstood here ?
Re: ROM upgrade
The upgrade ROM is just the one found in the ZX81.
The chip pinouts can be found here..
viewtopic.php?t=1249
Data sheet here...
https://pdf1.alldatasheet.com/datasheet ... D2364.html
The chip pinouts can be found here..
viewtopic.php?t=1249
Data sheet here...
https://pdf1.alldatasheet.com/datasheet ... D2364.html
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Re: ROM upgrade
EPROMs use a 28 pin package, but mask ROM chips (needing less control and supply inputs) can use 24 pin packages.
Mark
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: ROM upgrade
Yep, should have realized that. I'm thinking ahead to burning upgrade ROM code but I see that's not going to be easy