Sinclair ZX80 / ZX81 / Z88 Forums

dr beep wrote: ↑Sun Apr 28, 2024 10:41 am I had hoped to have a small loader that would allow loading more data in a 1K machine. Now bound on around 949 bytes.

Hope your deeams might have come true... Let us dream your new reaches if so!!

Then the new code looks like this (corrected also an error in preparing hl): MEMORY_END equ 0x4400 ; 1k SET_FAST equ 0x2E7 ; ROM routines IN_BYTE equ 0x34C ; / GET_BIT equ 0x385 ; / START: call SET_FAST ; load operations to be managed in FAST mode ld hl, 0x4400 ; cleanup and put stack at the very en...

DEC DE does not set any flag. my z80 asm is rusted :mrgreen: then 2 bytes more needed to set flags BUT a trick can be to put in the saved code, in the exact memory position of the target "call IN_BYTE", a call with the low address of the routine to be started, and then, when the load loop will over...

Mixing a bit of ROM in the initial part it should work. Moreover I checked and carry is always set on IN-BYTE return, so "or a" could be removed, but I noticed that IN_BYTE didn't increment hl, so I changed de to be a counter. With a program able to start with 4C high address another byte of stack c...

Pay attention to hacking attacks...
And prepare backups against ramsonware encryption

If it is a problem of timeout waiting for a signal,
a trick maybe to wait for the signal in the "pre loading" setup part, and immediately jump to the loop as soon as the signal is detected!
(code size there do not count )

I missed this!...
Pacman was missing in the 1k titles, and this release is ... WONDERFUL!!!
Compliment as usual Johan!!!

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...