Sinclair ZX80 / ZX81 / Z88 Forums

With the deletions you've done I do not understand how you will stop loading (before in loading loop I've put the checking of hl against de) and how you start the loaded program (before I've put a jp after the load loop completed) PS: the stack should be set at 4400 (call and push will start decreas...

The idea was to show two different high resolution frames. The second time the CRT beam should pass slightly shifted, between the previously displayed lines. This could produce a 192x2 picture, slightly flickering with overlapped pixels no clue on how to slightly shift the lines but the idea seems ...

The loader routine is just 17 bytes ("_BEG" to "_END"), and it is relocated to the end of the memory at the program start. Everything else is rewritten as all the rest of the memory during the load process. And become even 16 bytes because the loader stop when it starts overwriting itself (for now j...

I have at the moment no means to test it (my dev environment is broken), but the following program should be able to fully load 1008 bytes into memory (from 0x4000 to 0x4400 - 16 bytes)... The block to be load should be saved with standard routines and should be equal or bigger than 1008 bytes (if b...

384 lines :o :o :o what type of sourcery are you trying to use?? I was thinking about the fact that since the ZX is "executing" the display and on a standard machine if I remember properly just 25% is left for the program execution, doubilng the "execution of the display" should not be possible sinc...

... Advantages: 1. will load from 4000h instead of 4009h allowing to immediately fill this space with data 2. will allow immidiate utilization and filling of system variables needed by BASIC (program will start immediately the machine code) 3. will avoid the basic program skeleton to start the mach...

Beautiful collection!!!

This is an interesting thread. Is a long time that I was thinking that in order to fully (at least to the maximum extent) utilize the 1K memory it would be good to have a extremely small piece of code that (also reusing the standard load routines) could load programs. It means that first you would l...

As an additional comment, if you don't need floating point or flicker free running screen, ZX80 basic is both more efficient on memory and much much faster!

A bit longish but very nicely done. This series of videos take you step by step to the final design: 1. https://www.youtube.com/watch?v=pVQJxV9JCSE - ZX80/81 Video circuit generated from scratch 2. https://www.youtube.com/watch?v=T5yu_0K32s8 - Video circuit revealed, hi-res display of 256 x 192 pixe...