Sinclair ZX80 / ZX81 / Z88 Forums

Hi.

Do you have the LarkenUtils.rar file?

Is it possible to send me?

Thank you very much!

Regards

Hi All.

Regarding this post:

viewtopic.php?f=6&t=228

I need the file LarkenUtils.rar to test my floppy controller, but the link is not working anymore

Does anyone still have this file? If yes,Is it possible to send me?

Thank you very much!

Regards

Luciano

Yes.. all wires soldered manually..

zx81 KIT.. development board

Hi Pokemon Yes.. it is identical to z80 schematics plus NMI slow circuit... i mean.. i tried to soldered identical. (now the difference is A14 on pin 5 and controll pins on 16k expansion) I will double check the D6 and the pull up resistor. If you have another suggestion, hardware or software, to te...

16K Ram

Using MREQ and A14 the vertical lines are there all the time ,for text and low res games.. and disapear with HIRES

Using A14 only on pin 5 , low and hi-res works perfectly

Usiing Mreq and A14 (pin5 connected to pin 6) the Hires works well but in low res mode the picture have vertical lines..

Yes .. good news.. now is working fine.

Thank you all ..

Probably on zx80 Sinclair didn´t considered the future HIRES applications

On the zx81 ULA ,maybe, the "equivalent" internal circuit , pin 5 is conected to A14?

By the way.. do you have the ULA ZX81 schematics?

Hi Siggi Good News!! Your idea worked very well. Perfect! (Connecting pin 5 to A14 ) Even using the old 62256 sram,, 27c64 or 28c64 ,74LS or 74HC.. ALL combinations worked I will do more tests.. but i think it solved the problem.. take a look at the pictures (from tv grabber) attached Thanks a LOT !...

Hi Siggi Excellent Idea.. i will test today. Actually is not a zx80 anymore .. because it has a NMI generator upgrade and the zx81 rom 8k. http://searle.hostei.com/grant/zx80/zx80nmi.html So , in "theory" is a zx81 .. that is why i am trying to solve this.. I want a 100% compatible clone. (if possib...

Hi Siggi. Yes, probably during low refresh period the ROM add some data on data bus. I am planning to add some additional logic .. to disable the ROM or add some delay, during refresh period. (just to understand better the problem) Some idea about which signals needed to disable ROM in the right tim...