Patching IO demo

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By NYYRIKKI

Enlighted (5874)

NYYRIKKI's picture

17-03-2015, 08:05

Overflow wrote:

(Note: launcher detects R800 or MSX2+ w/ native overclocking
and then tries to lower freq to standard z80 mode;
launched also tries to switch from 60Hz to 50Hz)

How ever the switch to 50Hz seems to fail at least on OpenMSX causing DI:HALT situation. -> Switching to 50Hz before running the demo fixes this issue.

By mars2000you

Enlighted (5984)

mars2000you's picture

17-03-2015, 08:30

The switch to 50 HZ fails in all cases on blueMSX, considering that any 60 Hz machine is a MSX1 and that the switch can't therefore be executed. There are workarounds against this barrier (*) :

a) blueMSX has an original solution: go in Options/Emulation and replace Auto by 50 Hz for Video frequency : it will force 50 Hz on all 60 Hz machines, also on MSX1 machines !

b) If you prefer to keep the blueMSX Auto mode for the Video frequency (this mode corresponds to the working on the real machines), you can follow these steps on 60 HZ MSX2 and higher :

- boot without DSK inserted in drive A
- on BASIC screen, enter VDP(10)=2
- insert the DSK in drive A
- enter POKE &HF346,1
- enter CALL SYSTEM
- on the MSXDOS command line, enter AUTOEXEC

(*) I know that there are minor graphic glitches in a part of the demo with blueMSX, but that's another discussion.

By Marq

Champion (387)

Marq's picture

17-03-2015, 08:58

There's a weird lockup I've seen on MSX2 machines in general: if you HALT in order to wait for VBL right after setting the screen mode, the machine will not recover.

By Grauw

Ascended (10062)

Grauw's picture

17-03-2015, 10:05

Marq: Sounds like some kind of logic error. Probably interrupts were not re-enabled (note EI has a 1-instruction delay), or maybe the VDP interrupt enable flag was accidentally reset.

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