Search found 563 matches

by mrtinb
Sun Jan 21, 2018 9:28 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 15
Views: 456

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

Now I've connected it to a ZX81, but it gives me only white screen. It is a simplified version, that only has dip switches to select a button. (The PS/2 will be connected later when I program the microcontroller.) How can I debug this? I can read all pins on the EEPROM with a digital probe. The curr...
by mrtinb
Sun Jan 21, 2018 9:05 am
Forum: Development
Topic: Help Wanted
Replies: 8
Views: 103

Re: Help Wanted

And again pcbshopper.com is your friend. You can get them from allpcb.com with free shipping with DHL in 5 days for only $17.95. If you have trouble getting the gerber files saved on the library pc, and upload them to allpcb.com, you can just order the pcbs directly from easyeda.com for $18.98, but ...
by mrtinb
Sat Jan 20, 2018 8:34 pm
Forum: Development
Topic: Help Wanted
Replies: 8
Views: 103

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: 395

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: 15
Views: 456

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: 15
Views: 456

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: 15
Views: 456

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: 15
Views: 456

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: 15
Views: 456

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.