Search found 337 matches
- Thu May 17, 2018 10:54 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 123687
- Wed May 16, 2018 10:04 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 123687
Re: ZX81 ULA-in-a-CPLD
I am impressed with your progress, Andy. Well done and the board looks stunning.
- Mon May 14, 2018 12:28 am
- Forum: Hardware
- Topic: 28C64 in 2364 socket (28 pin to 26 pin)
- Replies: 10
- Views: 5423
Re: 28C64 in 2364 socket (28 pin to 26 pin)
Hi Martin,
Have you managed to squeeze your board inside the Zeddy case? I went to the SMD route and still the board a bit too fhigh. I should buy some flip-pins and try them.
Have you managed to squeeze your board inside the Zeddy case? I went to the SMD route and still the board a bit too fhigh. I should buy some flip-pins and try them.
- Fri May 11, 2018 10:12 pm
- Forum: Hardware
- Topic: zx spectrum in zx81 case
- Replies: 63
- Views: 39432
Re: zx spectrum in zx81 case
Do you have an oscilloscope? If so, check 14MHz (74HC004 - pin8) & 3.5MHz (Z80 clock - pin 6) signals on the board and also the Csyns signal on to pin 8 of miniDIN8 socket.
If you touch with a finger the bottom of your board near the 74HCU04 is anything changing on the screen?
If you touch with a finger the bottom of your board near the 74HCU04 is anything changing on the screen?
- Sun May 06, 2018 7:52 pm
- Forum: Development
- Topic: ZX Printer Belt
- Replies: 139
- Views: 85870
Re: ZX Printer Belt
Mark, much appreciated. Anything (any parts) for ZX Printer are welcome.
- Sun May 06, 2018 5:05 pm
- Forum: Development
- Topic: ZX Printer Belt
- Replies: 139
- Views: 85870
Re: ZX Printer Belt
They look great! Unfortunately my ZX Printer has got a cooked ULA and no replacement available
- Sat May 05, 2018 12:17 am
- Forum: Hardware
- Topic: zx spectrum in zx81 case
- Replies: 63
- Views: 39432
Re: zx spectrum in zx81 case
I did not say that was anything wrong with the crystal. The type of the 7404 inverter is critical. You should try to install there 74HCU04 instead of either HCT or HC.
- Fri May 04, 2018 11:02 pm
- Forum: Hardware
- Topic: zx spectrum in zx81 case
- Replies: 63
- Views: 39432
Re: zx spectrum in zx81 case
It works with 100ms RAM chips. I have them in my ZX Max 48K board. I think that in your case you are facing issues with the 14MHz clock, because the horizontal synchronisation is lost.
- Fri May 04, 2018 8:38 am
- Forum: Hardware
- Topic: zx spectrum in zx81 case
- Replies: 63
- Views: 39432
Re: zx spectrum in zx81 case
What make of the inverter (7404) do you have? The clock signals generator works much better with HCU series instead of HC. Personally I would recommend Philips, NXP or Toshiba chip in this application. TI make 74HCU04 is not hassle free. I've tested a few of them.
- Mon Apr 30, 2018 6:06 am
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 123687
Re: ZX81 ULA-in-a-CPLD
Andy, nice features