mrkwatkins / zxspectrumnexttests Goto Github PK

IIRC the swedish flag test doesn't check if the WAIT will pass when lines are equal, but horizontal of WAIT is less than actual horizontal position of display beam.

Should be possible to extend the test, there're few spare instructions in copper memory for some final WAIT+MOVE+WAIT+MOVE sequence testing the horizontal checks.

Check if it's possible to expand the test meaningfully to test basic transactions also at low CPU speeds, verify with older Next cores if the issue is detected (the source must be outside of BRAM mirroring, ie. NOT in bank5/bank7).

exact conditions to replicate the bug should be:

• 2T/2T DMA timing, 3.5MHz CPU, mem->mem, non BRAM source mem.
• then instead of "0, 1, 2, 3" is read "?, 0, 1, 2"

just to prevent some accident of somebody fixing partial flags and breaking final ones.

see http://www.z80.info/zip/z80-documented.pdf

Areas which should be transparent and display white background there is the $E3 pink colour instead.

It's not clear whether the blending-mode changes from core3.1.5 make the original setup of test invalid and this is correct result, or the original test should have displayed the screen as before and this is new core bug.

Investigate:

• if the test sets up blending mode explicitly enough (account also for the state modification by NextZXOS)
• if the pink or white background should be result of such setup with new core
• fix the test or report core bug
• and BTW add test for the new blending modes
• and probably improve the old test as well, as even core 3.0 produced different results depending whether ula+tiles or just-ula was blended.