My first wire wrap: Wilf's AT keyboard interface

Discussions about Sinclair ZX80 and ZX81 Hardware
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gammaray
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by gammaray »

Great news! Can't wait to see output from your temporary dipswitch.
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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mrtinb
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by mrtinb »

Before I went to bed I found one switch was not pulled to ground. Maybe it's a resistor or socket that's faulty. Maybe I have time tonight for further investigation with my logic probe.
Martin
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ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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mrtinb
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by mrtinb »

Image

I’ve fixed error on pin 23. It’s now LOW as the others.

The error on pin 5, I don’t know what’s wrong. My only suggestion would be to replace the EEPROM with a new one and see if that fixes the problem.

Image
Martin
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mrtinb
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by mrtinb »

I've changed the EEPROM, and checked that A13 is not connected to anything other than A5 on the EEPROM. It didn't fix anything.

Can anyone suggest why A13 is Pulse-Low, when everything else is Pulse-High-Low?

When the card is not connected to the ZX81, then A13 is Pulse-High-Low.
Martin
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ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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mrtinb
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by mrtinb »

I just realized my EEPROM never gets Chip Enable signal, at the Arduino controller is not yet implemented. I need a switch for Chip Enable instead.

Back to the drawing board. :)
Martin
https://zx.rtin.be
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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gammaray
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by gammaray »

Why is Vss on EPROM connected to 0V? Is that supply or sink voltage?

Nevermind it's ground.
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by mrtinb »

I assume it’s GND on the 28C64 EEPROM I’m using. Look at previous post for my schematic
Martin
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ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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gammaray
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by gammaray »

Is it significant A13 is not connected to ROM? Nor internal RAM?

A14 and 15 connect to ULA.
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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gammaray
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by gammaray »

I saw the post and schematic but I second guess everyone and every thing as there are land mines everywhere!
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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gammaray
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Re: My first wire wrap: Wilf's AT keyboard interface

Post by gammaray »

The ROM routine sets RAMTOP for 1k ( I assume you do not have a memory pack on back) and maybe never addresses with A13.
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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