Search found 1940 matches

by XavSnap
Fri Dec 08, 2023 8:12 am
Forum: Hardware
Topic: 8 Analog ouput card [AN7225]
Replies: 7
Views: 12596

Re: 8 Analog ouput card [AN7225]

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by XavSnap
Thu Dec 07, 2023 8:43 pm
Forum: Hardware
Topic: 8 Analog ouput card [AN7225]
Replies: 7
Views: 12596

Re: 8 Analog ouput card [AN7225]

Wiring diagram updated:

Vss> GND
Vref on a terminal
\LDAC> GND or /WR (jumpers)
\ROMCS>high

Picture in the next message >>>
by XavSnap
Thu Dec 07, 2023 7:27 pm
Forum: Hardware
Topic: 8 Analog ouput card [AN7225]
Replies: 7
Views: 12596

Re: 8 Analog ouput card [AN7225]

Thanks Paul & Mark, @Paul: Yes,better to force /ROMCS to deactivate the RAM/ROM process. (ROMCS:high & RAMCS:high to get an ambiguous/undetermined stat) The MEMOTCH HRG also use the 0-1fff RAM location. @Mark: Thank, i had to primary set the DAC, and feed the DATAS in the buffer. I had to use it wit...
by XavSnap
Wed Dec 06, 2023 9:13 am
Forum: Hardware
Topic: 8 Analog ouput card [AN7225]
Replies: 7
Views: 12596

8 Analog ouput card [AN7225]

Hi, I plan to build a ZX81 card around the AN7225 chipset. But i cant figure out the "\LDAC" process ! Can you help me, please. an7225.JPG AD7225 Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD7225.pdf My wiring diagram (POKE 0-7,value to set the output voltage= POK...
by XavSnap
Sat Dec 02, 2023 4:23 am
Forum: GAMES
Topic: [Adventure-Fr] "La maison du professeur Folibus"
Replies: 10
Views: 13154

Re: [Adventure-Fr] "La maison du professeur Folibus"

More infos:

Video "ZX81 Adventure: The Trevor Toms System!" by WhatHoSnorkers.
https://www.youtube.com/watch?v=p4_H08SNBPg
by XavSnap
Mon Nov 27, 2023 2:28 am
Forum: Hardware
Topic: Proportional Joystick interface PCB [ZX-Appeal]
Replies: 0
Views: 11645

Proportional Joystick interface PCB [ZX-Appeal]

"Proportional Joystick interface" PCB from Fred Nachbaur [ZX-Appeal #Mar-Apr-89]
Proportional_Joystick_1.jpg
GERBER & Kicad project:
http://abandon.pcbs.free.fr/ZxAppeal.htm

Have Fun.
by XavSnap
Sat Nov 25, 2023 4:46 pm
Forum: Hardware
Topic: ZX-81 Corrupted text display
Replies: 26
Views: 20455

Re: ZX-81 Corrupted text display

https://www.sinclairzxworld.com/download/file.php?id=13956&t=1 BadUDG.jpg "CLEAR " ... The UDG table seem to be in the right memory offset. Char. offset+0 : NOK ("00000000")>("00000100") Char. offset+1 : NOK ("00000001")>("00000101") Char. offset+2 : NOK ("00000010")>("00000110") Char. offset+3 : N...
by XavSnap
Sat Nov 25, 2023 2:14 am
Forum: Hardware
Topic: PI-PAK ZON X-81 MPSG PCB.
Replies: 0
Views: 13407

PI-PAK ZON X-81 MPSG PCB.

Hi, the "Original" PCB is now available. http://abandon.pcbs.free.fr/BI-PAK/ZONX81/Bi-Pack_ZONX_1.jpg http://abandon.pcbs.free.fr/BI-PAK/ZONX81/Bi-Pack_ZONX_2.jpg http://abandon.pcbs.free.fr/BI-PAK/ZONX81/Schema_ZON_X81.jpg Gerber & Kicad v6 project: http://abandon.pcbs.free.fr/BI-PAK.htm ( More BI-...
by XavSnap
Fri Nov 24, 2023 2:43 am
Forum: Hardware
Topic: ZX-81 Corrupted text display
Replies: 26
Views: 20455

Re: ZX-81 Corrupted text display

Hi Mike, If the Basic is ok, the UDG (characters table) is located at the end of the ROM ($1E00). Check the ROM solders or clean the ships connectors. The address line A12 can be cut or short-cut by the new keyboard. A12= "67890" keyboard line (D3 diode). And have a special look to the keyboard conn...
by XavSnap
Thu Nov 23, 2023 10:15 pm
Forum: Hardware
Topic: ZX-81 Corrupted text display
Replies: 26
Views: 20455

Re: ZX-81 Corrupted text display

Hi Mike,

Something's wrong on the A3 memory address line, on the ULA or the ROM ship.
If you type "R", is there 3 displayed characters ? (to check if the BASIC/RAM is ok)
Type "V" then newline, to display "0/0"...

Check R18-R26 resistors. (A3'=R25)
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