My first wire wrap: Wilf's AT keyboard interface
Re: My first wire wrap: Wilf's AT keyboard interface
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
Re: My first wire wrap: Wilf's AT keyboard interface
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.
Re: My first wire wrap: Wilf's AT keyboard interface
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.
Re: My first wire wrap: Wilf's AT keyboard interface
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.
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.
Re: My first wire wrap: Wilf's AT keyboard interface
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.
Back to the drawing board.
Re: My first wire wrap: Wilf's AT keyboard interface
Why is Vss on EPROM connected to 0V? Is that supply or sink voltage?
Nevermind it's ground.
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
Re: My first wire wrap: Wilf's AT keyboard interface
I assume it’s GND on the 28C64 EEPROM I’m using. Look at previous post for my schematic
Re: My first wire wrap: Wilf's AT keyboard interface
Is it significant A13 is not connected to ROM? Nor internal RAM?
A14 and 15 connect to ULA.
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
Re: My first wire wrap: Wilf's AT keyboard interface
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
Re: My first wire wrap: Wilf's AT keyboard interface
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