Philips NMS 8245 evolution MSX 2+ 60 Hz

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By ramonsmits

Rookie (20)

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11-02-2022, 12:49

I'm not specifically interested in the MSX2+ upgrade, only in features like:

- 60hz
- hold h to boot in 50hz
- 2400 baud
- hold a during boot to skip slot 1
- hold b during boot to skip slot 2

Seem like super useful startup options to have for any MSX.

I got a regular MSX2 8235 so not sure if @NYYRIKKI ROM would then work? I currently interpret it as requiring MSX2+?

I think even better would be the explanation on how to build/patch/reverse engineer such so that such changes are documented and even be used to patch ROM's from other machines too.

By hamlet

Scribe (4105)

hamlet さんの画像

11-02-2022, 14:58

NYYRIKKI wrote:

...I didn't want to change any existing code byte in ROM that was not absolutely must, so I came up with this simple logo that could be represented with mathematical ways and therefore coded in to the very small space that was left behind the BASIC extensions.

Brilliant, NYYRIKKI! Kudos.

By NYYRIKKI

Enlighted (5949)

NYYRIKKI さんの画像

15-02-2022, 04:37

ramonsmits wrote:

I'm not specifically interested in the MSX2+ upgrade, only in features like:

- 60hz
- hold h to boot in 50hz

This one I have documented for MSX2... It was designed for 8250, but I guess any typical MSX2 should do...
See here: https://www.msx.org/forum/msx-talk/hardware/msx2-rom-flash-s...

引用:

- 2400 baud

I guess any MSX should be able to do this although default can be only set on MSX2 and and MSX2+
IIRC there was a bug in this though, so if you still don't save on 2400 speed after SET SCREEN & reset then try to change the default printer type and try again. During reset the machine may fetch a saved speed bit from wrong place. :(

引用:

- hold a during boot to skip slot 1
- hold b during boot to skip slot 2

Seem like super useful startup options to have for any MSX.

Yes, well these patches are not 100% accurate as they don't consider BASIC-cartridges, but 95% of the time they improve quality of life a lot.

引用:

I got a regular MSX2 8235 so not sure if @NYYRIKKI ROM would then work? I currently interpret it as requiring MSX2+?

Indeed... I have not ported these mods back to MSX2 version of the ROM, but since this part has not really changed since MSX1, reimplementing the mod should be quite trivial. How ever if you are man to change the ROM, then you are likely man to change the VDP as well... and even if not, I guess the MSX2+ ROM mostly just affects the MSX2+ stuff and so the wrong VDP should not cause problems unless you run MSX2+ software. (just speculating & thinking out loud, not tested scenario)

引用:

I think even better would be the explanation on how to build/patch/reverse engineer such so that such changes are documented and even be used to patch ROM's from other machines too.

Sorry to say, but I think you are wrong... I feel happy to give my work for other people to examine, evaluate and reverse engineer if they wish, but this kind of documenting is a totally useless effort. If the person understands my changes the documentation is totally useless to him. If he doesn't understand so well, I could write 200-page book without ever making him any vicer. I'm always happy to point to right direction though.

Why I don't just post nice download links is because most of the people just don't consider enough to think about such things as RTC defaults, date format, font, logo/default frequencies, localization codes, #F4-port, key repeat, PLAY-command speed, currency symbol, RAM check, function keys or differences in keyboard layouts on their own. In these cases I'm maybe a bit pain in the ass to ask a lot of stupid questions, but in the end I usually get the job done in a bit more accurate way than the customer maybe originally thought.

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