Sinclair ZX80 / ZX81 / Z88 Forums

Thanks for all the feedback, I managed to test the ram with the m1not circuit activated and de-acativated here are the results: 1. m1not de-activated 2. Poked 16389 with 255, then new, peeked 16389 and got 192, as expected ramtop now 49152 3. Made a REM line with 512 bytes, copied this all the way t...

Thanks for clearing that up Siggi

Does anyone know where I can find a test program that is bigger than 16k ?

Thanks Gozzo, To be honest I’m not planning to write any code that big. I have only been able to get >16k programs to work on the ‘eighty one’ emulator on my pc, when I’ve typed in on a real zx81 they all crash, m1not or not?, probably because of the d-file straddling the 32k boundary, I’ve not trie...

So I went back to basics and resoldered a new 1N60P Ge diode and 4k7 resistor as the M1not circuit (A) as shown in my previous post and to my delight I was able to run some M/C above 32767 in my battery backed ram circuit (attached). This also worked with Wilf Rigter's 32k barebones ram circuit, sli...

Thanks Gozzo, The m1not circuit seems to be very elusive, I've been scouring the net for more than a month to find something different to this one (A) attached, which doesn't allow me to use M/C between 32-48K with full 64k available. I found this one yesterday from Siggi on a German forum but haven...

Thanks both for your prompt responses My Z80 m/c programming skills are limited, but growing, so I need to keep the software side as simple as possible I'm still decimal, so sorry to all the Hexer's The m/c test i'm using is: 32768 LD BC, 65535 1, 255, 255 32771 RET 201 Then PRINT USR 32768 Of cours...

Hi all, This is my first post to the forum. I have installed 32k of internal ram to one of my ZX81's and would like to place some m/c in the 32-48k area. However the circuit I used has the A15 and /M1, which gives me 16-32k and 48-64k, but following various threads (m1not in particular), I believe i...