Sinclair ZX80 / ZX81 / Z88 Forums

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...

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-...

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...

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)

Welcome aboard Jean-Robert.
How is your fiend Yannick?

Thanks Greg,
Remember me a jackpot game.


Good job.
Happy Halloween day...

Motor speed: Cylinder max speed turn around 1 rotation per second. The speed variator can reduce this speed at -1/4= 0.75 rotation per second. 1RPS(Second) =60RPM(Minute) Cylinder to the motor: 40touth/8tooth= 5 multiplier. Motor to the cylinder: 8tooth/40touth= 0.2 multiplier. 60RPM x 5= 300 RPM 3...

The sound of a picture challenge : Simply link the resistor output on a cheap PC USB sound card (2$) to avoid burning the main inboard sound card... The positive or negative low frequency signals can destroy the sound card ! The voltage had to be less than 5v to avoid to saturate the sound card rec...

ATARI ST Card (article's PCB):

Kicad v.6 & Gerber files: Note:
In the article, the component's side in the top view is false.
The photo gave the right component side.

AMSTRAD CPC 464/6128 analog card: GERBER/Kicad 6 project (NOT TESTED):
http://abandon.pcbs.free.fr/mageco.htm