Depends on which version of the AT28C64 is used. One version has pin 1 as a no connect, the other version has an open drain RDY/BUSY (Ready/Busy) output.
Microchip / Atmel datasheet here.
Looks like Microchip have the older Atmel datasheet on their site! And that the version with the RDY/BUSY was dropped at some time.
A rebranded Microchip current datasheet is here. This has pin 1 as a no connect.
Mark
Replacement ROM
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1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
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Re: Replacement ROM
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: Replacement ROM
The data sheet I pointed to has it as NC and to further complicate it that first data sheet in your link as it as RDY/BUSY (or NC)
Surely it cannot be both?
Surely it cannot be both?
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1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Replacement ROM
No, can't be both.
Nice of Atmel to make it rather confusing
Anyway, if we take the Microchip branded datasheet as being the current version, all new chips will have pin 1 as NC.
Mark
Nice of Atmel to make it rather confusing
Anyway, if we take the Microchip branded datasheet as being the current version, all new chips will have pin 1 as NC.
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: Replacement ROM
On that we are in Bon Accord. 