Sinclair ZX80 / ZX81 / Z88 Forums

The NMI routine increments the alternative A register. The SLOW/FAST routine starts the NMI generator, and tests within a time frame if this register is incremented. With the ZX81 ROM in the ZX80, this does not happen. If bit 6 of CDFLAG indicates a change to SLOW, this test will indicate if SLOW is...

Thank you for writing about the issue with rezurrection. I seem to remember trying it some years ago and that it worked correctly, so possibly some later improvement introduced the issue. I think it is still unknown how the ULA works exactly, but if something works on a real ZX81 it should work on a...

@Moggy: it seems that sz81 hangs with commander versions > 1.7; the joystick (which is not supported) initialization seems to result in a ZXpand read from an unopened file. Now this can be prevented in the ZXpand emulation or the joystick initialization needs a modification. For now, I've created a ...

Hello Greg, under Linux, I have to have upper case names of files and directories, and then the commander does open a subdirectory. I'm not sure how that might translate to Win 7...

I had to tweak the Makefile.OSX as well to get it to build properly on M1: Change: CFLAGS+=-mmacosx-version-min=10.6 -arch i386 -arch x86_64 to CFLAGS+=-mmacosx-version-min=13.2 and Change: LDFLAGS=-mmacosx-version-min=10.6 -arch i386 -arch x86_64 to LDFLAGS=-mmacosx-version-min=13.2 Also, replace ...

or before calling DEC2FP may help

The particular page has been moved to https://www.weggetjes.nl/sg/zx81ce.html
Some links on that page still need to be updated.

It is currently available at https://weggetjes.nl/jszeddy/jszeddy.html

Normally the path to the data is determined at compile time. When run from the command line, sz81 shows "PACKAGE_DATA_DIR". Perhaps this helps in determining the directory where sz81 expects it to be installed/run from.

sz81's version with "exploratory features" at http://rullf2.xs4all.nl/sz81/ renders sound with code from the "Unreal Speccy" project (following a recommendation by Yerzmyey; a current link is the first one in https://forum.tlienhard.com/phpBB3/view ... 958#p49958).