Sinclair ZX80 / ZX81 / Z88 Forums

Testing out my new External multi ROM and Expansion Bus extender :-) 8 ROM banks of size 8192 bytes, selected with DIP - BUT requires the original ROM in ZX81 because of display generation, tested with the followin ZX81 ROMs: * 550, 622, 649, SG and X2 Also tested, but not working correctly because ...

OK - so after 3 tries it finally pays off - got a version running that seems to be working fine. Only thing is that font table is selected by setting I=n*4 only, and not adding 224 as described in Wilfs documentation. Not sure if its mine that has a flaw in the wiring or eprom programming - but hey,...

Hi, Just want to hear if someone has build the CHR$X16 as described by Wilf? image002.gif I'm asking, because I've tried but ran into some smaller issued - just want to hear from someone, that it can be done, before diving into more detailed investigation of my board. It looks semi ok, but as can be...

I decided to give this a go on real hardware as well, trying to avoid opening and modifying the ZX81. Only modification to my setup, which has been done long time ago - My ZX81 has internal 16K RAM upgrade (WRX compatible) and a composite mod. I know it looks like chaos, but huuraaa - it's working -...

I think I understand the reason for using tzx, it allows the creation of very accurate tape images and allows to pack many program blocks in a single file. Probably excessive accuracy is even uncomfortable (I'm thinking at the leading noise in a tape), but it is still possible to extract a P file f...

Monkey Kong - Scan-Bit-Software (SBS)

Requires 16K Ram and version 1 of the rom
Entry at spectrumcomputing

I am using the ZX81 Tape Converter found her: https://www.zx81stuff.org.uk/zx81/tapeutils/overview.html It also has the option to save as P file, I just forgot - but will try to remember next time. Creating a P from TZX should be easy in most cases, but I don’t know of any tools that can do that. Pl...

Squeeze Play - Scan-Bit-Software (SBS)

Requires 16K Ram and version 2 of the rom
Entry at spectrumcomputing

mrtinb wrote: ↑Tue Apr 03, 2018 9:29 pm Lambda 8300 with ZX81 ROM (I think).

I inserted a ZX81 ROM, but that does not work. Maybe the Lambda insists on a modified ZX81 ROM.

https://youtu.be/Eyz3EM5ADJY

I believe what you have in the video is the original 4K rom for the ZX80

EDIT:
(which I just now saw is also in the comments

There is a solution to ZX81s that don’t produce a ‘back porch’. In fact, there are a number of different solutions, both DIY, ready build modules and professional fitting services. These should work with a Lambda, if the problem is in fact a missing ‘back porch’. One of the popular modules is PokeM...