Search found 560 matches

by mrtinb
Sat Jan 20, 2018 8:34 pm
Forum: Development
Topic: Help Wanted
Replies: 5
Views: 52

Re: Help Wanted

If you have access to a browser, you can easily create schematic and pcb with https://easyeda.com/ . That's what I use.
by mrtinb
Wed Jan 17, 2018 9:42 pm
Forum: Development
Topic: old magazine article -- interesting ! ??
Replies: 14
Views: 377

Re: old magazine article -- interesting ! ??

It seems building this unit is useless unless someone has the content of the EPROM Operation System Software sold from the magazine.
by mrtinb
Tue Jan 16, 2018 7:11 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 389

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

Wouldn't that limit to only 8 external devices?
$FE, $FD, $FB, $F7, $EF, $DF, $BF, $7F
by mrtinb
Tue Jan 16, 2018 5:27 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 389

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

But wouldn't this interface conflict with any other device with A0=0? Wouldn't it conflict with any device with even I/O address?
by mrtinb
Tue Jan 16, 2018 4:48 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 389

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

Wilf's AT keyboard ( and backup copy here ) uses only A0, A8 to A15. That means he reads these addresses: 11111110???????0 11111101???????0 11111011???????0 11110111???????0 11101111???????0 11011111???????0 10111111???????0 01111111???????0 That does not give I/O $FE, because all he ensures is tha...
by mrtinb
Tue Jan 16, 2018 4:38 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 389

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

So now the wires have been wrapped and this is the first prototype with DIP switches in place of Arduino controller and keyboard. https://trello-attachments.s3.amazonaws.com/598af660300e0d55b35f5755/5a36e7929ce3cfa9702728e9/7152525c2e63fbd530b045514d9478d9/photo.jpg https://trello-attachments.s3.ama...
by mrtinb
Sun Jan 14, 2018 9:14 am
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 389

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

My plan is to replace it with an Arduino Pro Mini, but this first version will just have the DIP switches to see the concept working.
by mrtinb
Sat Jan 13, 2018 10:46 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 389

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

I've redesigned the board after I got hold of a wire wrap version of the edge connector. There's still a lot to wire. :) https://trello-attachments.s3.amazonaws.com/598af660300e0d55b35f5755/5a36e7929ce3cfa9702728e9/1cebe37c1db1299cd23f1e0235eafa73/photo.jpg https://trello-attachments.s3.amazonaws.co...
by mrtinb
Fri Jan 12, 2018 8:30 pm
Forum: Hardware
Topic: Chroma 81 - SCART and Colour interface for the ZX81
Replies: 133
Views: 8538

Re: Chroma 81 - SCART and Colour interface for the ZX81

gammaray wrote:
Fri Jan 12, 2018 6:53 pm
Is Chroma compatible with the UDG characters using the UDG board by Andy, is it?
If I remember correctly Chroma implements UDG by itself.