Sinclair ZX80 / ZX81 / Z88 Forums

Thanks for your reply bola_dor Don’t worry, I’ll work it out eventually... but not today :mrgreen: Mark 20200923_202643.jpg Ok Tr is conected to +5v . I marked in red points in continuity with 5v rail. Cian are GND And yellow and violet the other leads from Tr Tr is marked as 238B 20200923_203614.j...

Is the lower RAM made up of eight x MCM4517 DRAM chips? Thanks for posting the NE555 based charge-pump circuit for generating the +12V supply. I have a question, I can’t make sense of the circuit around Q1. The circuitry for the base makes sense, it’s monitoring the voltage on the +12V supply. So I...

Make sure that nothing else is still connected to the video out center pin..
I had this TS1500 that drove me krazy because this coneccion from behind

Thanks Xav!
I'll try this later..
I remember 16418 from 35 years ago...
This may be usefull speedwise if I want to use those two bottom lines..

1 REM [HEX:\ 2A,0C,40,EB,2A,0C,40,01,\ 21,00,09,01,F7,02,ED,B0,\ 01,1F,00,ED,42,EB,23,36,\ 00,0B,ED,B0,C9 ] 2 CLS 4 POKE 16418,0 5 FOR A=0 TO 24 6 PRINT AT 23,A;"*HELLO*" 7 RAND USR 16514 8 NEXT A 9 GOTO 5 10 SAVE"SCROLL" 20 RUN ;------- TASM ASM mnemonics. ------- ; Compile this file using: ; Set ...

20200920_232124.jpg Just to show how it looks.. This is a CZ Spectrum (argentinian clone) the board is a slightly modified ISSUE 6A, low ram is +5v only.. many of them had the PCF1306P but many others had this ZX8401 board. Perhaps because of lacking of stock... the first argentinian Spectrum CZ200...

20200920_232124.jpg Just to show how it looks.. This is a CZ Spectrum (argentinian clone) the board is a slightly modified ISSUE 6A, low ram is +5v only.. many of them had the PCF1306P but many others had this ZX8401 board. Perhaps because of lacking of stock... the first argentinian Spectrum CZ200...

I am working on a game with a vertical classic SCROLL. and adapting it to be compiled with MCODER II. even when MCII documentation states that SCROLL is treted as in BASIC every time a SCROLL is found it stops with an inverted [?] and waits for a key ading a wite line.. ressult is disastrous to the...

I am working on a game with a vertical classic SCROLL. and adapting it to be compiled with MCODER II. even when MCII documentation states that SCROLL is treted as in BASIC every time a SCROLL is found it stops with an inverted [?] and waits for a key ading a wite line.. ressult is disastrous to the ...

Here you can find TS1500 schematics https://www.sinclairzxworld.com/viewtopic.php?f=7&t=1582#p16357 As Mark suggested you can try replacing C33, C35, C37, C39. Here you can se how is it done with Spectrum that has similar low ram layout. https://spectrumforeveryone.com/technical/fixing-vertical-jail...