Sinclair ZX80 / ZX81 / Z88 Forums

Siggi, Thanks, but the question asked by Rich, as I could understand, was from the PROGRAMMER point of view. The purpose, clearly, is to ask the programmer to include (if possible) a Low Res and a HGR version of the same programm. The programm detect if the required configuration is avaible and, ac...

With the various ways of creating hi-res graphics on the ZX81, what is the best way of detecting whether it is available? IMHO it is not possible. IMHO the application using HRG (or UDG) and the HRG (or UDG) environment are"fixed coupled", because the appliction need to know, where the HIRES image ...

starting from the top - with /busrq - we see it get asserted. The signals here are all active when low. /busak follows. This is the z80 confirming that it's sleeping. There is a period of silence in the trace and then you see little blips where the /wr line is asserted. This should poke values into...

Another suggestion has been an ethernet board for the ZX81 - now with 16K I am not sure the ZX81 could handle the internet - but maybe email is a possibility? Thoughts / comments as always.... Tom already played around with Ethernet. He used a controller board, where the IP-stack is handled by a sm...

I would try to write some well knows bytes (1,2,...255) to a safe location (>32K, 8-16K), where the Zeddy does not crash on wrong data (like when data with bit 6 set are put into the display file) and check the data there. And /HALT also needs to be set so HIGH (the ULA uses that signal). Does the z...

XavSnap wrote:Hi,
Something's wrong???

Yes: the "ZX81-16K RAMPACK" contains 64K ram

Siggi

What is needed to run the UDG version on the normal ZX81 - is this the same mod to the 16K RAM pack as mentioned for the HRG graphics? No, it needs ram, that gets its address lines from the rom socket. I have such a ram only in my web-server Zeddy. Maybe some day I could port that program to use Ma...

Perhaps you could give us some details, which data should be transferred to which location? Sometimes only one wrong bit might crash the Zeddy (or a nuclear power plant, or a Robo-Doc, or s..) Siggi PS: It's easy to crash a Zeddy, when you load a program, which has been saved in SLOW mode, during FA...

Here is a little game (written in BASIC only) I wrote for CSSCGC some years ago. The ZIP files includes 2 program versions: INTERCEP.P is the normal version, INTERC-U.P a version using UDG starting at 8K (and screenshots of them). Instructions are included in the programs. They are also available at...

Siggi - I sent you an email last night to you at the zx81 dot de address. Do you check this one still? Yes, but nothing arrived. I have to check the spam filters ... It shows the address decoding for external ROM. The decoder is enabled with /rfsh so the memory isn't used for character generation. ...