Search found 1821 matches

by 1024MAK
Tue Jan 16, 2018 7:28 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 350

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

Yes, a total of eight I/O devices (assuming all are read and write devices).

Mark
by 1024MAK
Tue Jan 16, 2018 7:01 pm
Forum: Hardware
Topic: My first wire wrap: Wilf's AT keyboard interface
Replies: 13
Views: 350

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

For the I/O, Sinclair treated address lines A0 to A7 as I/O select lines, and in doing so saved money on the logic required for full address decoding. A0 low (with A1 to A7 all high) then selects one I/O device. A1 low then selects the next I/O device. Etc.. So the ZX80, ZX81 and the ZX Spectrum all...
by 1024MAK
Mon Jan 08, 2018 4:41 pm
Forum: Hardware
Topic: Improving Timex/Sinclair Tape Loading
Replies: 70
Views: 3110

Re: Improving Timex/Sinclair Tape Loading

Diodes (and LEDs):-
Image
Image

Mark
by 1024MAK
Sat Jan 06, 2018 6:08 pm
Forum: Hardware
Topic: TS1000's (ZX81's) black screen
Replies: 10
Views: 256

Re: TS1000's (ZX81's) black screen

PokeMon wrote:
Sat Jan 06, 2018 6:00 pm
You can order them quite cheap from Aliexpress:

https://de.aliexpress.com/item/100-teil ... 82982.html

100 pieces with 12 cent each - no shipment fee.
Thanks :D

Mark
by 1024MAK
Sat Jan 06, 2018 2:22 pm
Forum: Hardware
Topic: TS1000's (ZX81's) black screen
Replies: 10
Views: 256

Re: TS1000's (ZX81's) black screen

Good that you have found a supplier of MPS2369 transistors. When I looked a couple of months ago, I could not find any that were in stock apart from on eBay.

Mark
by 1024MAK
Fri Jan 05, 2018 11:38 pm
Forum: Hardware
Topic: TS1000's (ZX81's) black screen
Replies: 10
Views: 256

Re: TS1000's (ZX81's) black screen

The only source of ZTX313 or MPS2369 transistors appears to be eBay...

Mark
by 1024MAK
Tue Jan 02, 2018 8:09 pm
Forum: Development
Topic: ZXMore development thread
Replies: 7
Views: 166

Re: ZXMore development thread

Oh yeah :D

Mark
by 1024MAK
Tue Jan 02, 2018 1:09 am
Forum: Hardware
Topic: Spectrum+ 128k repair help (No CPU clock signal from working ULA)
Replies: 6
Views: 132

Re: Spectrum+ 128k repair help (No CPU clock signal from working ULA)

When a 16k or 48k ZX Spectrum is reset or powered on, one of the first things that the code in the Sinclair BASIC ROM does is to set the border white. It then does a memory check ( not a full memory test) to see how much RAM is fitted. During this test, values are written to all the 48k RAM area, th...
by 1024MAK
Mon Jan 01, 2018 12:58 am
Forum: Hardware
Topic: Chroma 81 - SCART and Colour interface for the ZX81
Replies: 133
Views: 8454

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

Yes, the current value of D_FILE is stored in the system variables area (two bytes at 16396), because D_FILE moves around in memory. It moves whenever the BASIC program length changes.

See chapter 27 and 28 in the ZX81 BASIC Programming manual.

Mark
by 1024MAK
Mon Jan 01, 2018 12:50 am
Forum: Sinclair Misc
Topic: Happy New Year
Replies: 5
Views: 172

Re: Happy New Year

Roll-up! Roll-up! Welcome to a brand new year! Boy, will we have a show for you! For our old time friend, Zeddy of Sinclair will continue it's amazing compute and display light fantastic for it's thirty-eighth year! Don't hold back, come now, right to the front, you don't want to miss even a minute!...