Turbo Z80 mode on MSX turbo R?

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By Retrofan

Paragon (1214)

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29-04-2012, 11:07

Hi, I would like to know if it’s possible to use the 5,38 Mhz (1,5 multiplier of 3,58 Mhz) turbo option for Z80 in the Turbo-R as well as with the Panasonic FX, WX and WSX MSX2+ computers. This could be handy in some situations when the R800 speed isn't really needed (too fast gameplay with R800 and smooth gameplay without framedrop with 5,38 Mhz).

According to my information the Turbo-R has the Toshiba T9769C engine like the Panasonic A1-WSX (look picture of engine in this file, 2nd page) http://www.msxarchive.nl/pub/msx/docs/hwmodsetc/msxa1wsxmemo...

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By mars2000you

Enlighted (5515)

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29-04-2012, 11:23

.

By Manuel

Ascended (15842)

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29-04-2012, 12:04

Good question, but I've never heard about this possibility.

By mars2000you

Enlighted (5515)

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29-04-2012, 13:41

I don't think all Panasonic MSX2+ have the T9769C engine, probably it's only the case of some machines, when the T9769B chip was no more available.

Check this Japanese page : http://usbsecretbase.michikusa.jp/a1fx_wx/ram.html

By Jipe

Paragon (1366)

Jipe's picture

29-04-2012, 13:58

on this page i can see a picture with T9769A and next with T9769B strange Question

By mars2000you

Enlighted (5515)

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29-04-2012, 14:14

You will also notice that this page is only about A1-FX and A1-WX.

But this Korean page is about only A1-WSX and you can see a T9769C chip :

http://blog.naver.com/PostView.nhn?blogId=isisjr&logNo=10106...

But for this Japanese page, we have a T9769B chip in the A1-WSX :

http://usbsecretbase.michikusa.jp/a1wsx/ram.html

By Retrofan

Paragon (1214)

Retrofan's picture

29-04-2012, 15:26

Yes, I've also seen it, very interesting, so maybe it's possible to have the Z80 turbo as well on Turbo-R as the A1WSX in the first post also has the 9769C chip. So, I think the 9769C in the Turbo-R is capable of doing the same, but maybe it's blocked by the S1990, because I could not notice any speed difference when using the classic OUT's:

OUT 64,8: OUT 65,0 (5,38 Mhz)
OUT 64,8: OUT 65,1 (3,58 Mhz)

Maybe we need another OUT instruction to activate it?
If the S1990 blocks it, I would not know for what purpose... It would be a challange to bypass it then...

By Retrofan

Paragon (1214)

Retrofan's picture

29-04-2012, 15:51

mars2000you wrote:

I don't think all Panasonic MSX2+ have the T9769C engine, probably it's only the case of some machines, when the T9769B chip was no more available.

Check this Japanese page : http://usbsecretbase.michikusa.jp/a1fx_wx/ram.html

I think you're right as the WSX was the latest MSX2+ from Panasonic, so they were out of stock with the T9769B and used the T9769C instead.

Here another WSX with the T9769C chip:
http://wernerkai.blogspot.com/2011/07/instalando-512kb-de-ra...

Still remains the question if we can activate the 5,38Mhz clockspeed with the T9769C of the Turbo-R when it's in Z80 mode. According to this site the T9769C in the Turbo-R also has Z80B build-in instead of Z80A: http://mo5.com/musee-machines-msxturbor.html

By Manuel

Ascended (15842)

Manuel's picture

29-04-2012, 17:17

Actually, I don't see any advantage of having this. The cool thing of the R800 is that it won't destroy the sound pitch and it's even faster... Who would be against that?

By sjoerd

Hero (593)

sjoerd's picture

29-04-2012, 19:34

There could be a advantage when accessing the VDP. Dunno.

By Retrofan

Paragon (1214)

Retrofan's picture

29-04-2012, 20:09

Manuel wrote:

Actually, I don't see any advantage of having this. The cool thing of the R800 is that it won't destroy the sound pitch and it's even faster... Who would be against that?

R800 is great, but if I want to play Aleste 2 in R800 mode (because of some framedrop in Z80 mode), FM sound is corrupted because of a bad replayer? Normally there's no problem using MSX-Music with R800?
I would like to test if I got the same problem when using 5,38Mhz turbo feature with MSX-MUSIC. And, I find it interesting to know if the T9769C of the Turbo-R is still capable doing the same as MSX2+ or Panasonic blocked it when introducing the MSX turbo R. (some of the newer Panasonic FS-A1WSX's do have a T9769C with the turbo feature for Z80, so I think it's capable). Until now no one has given the answer... Who dares? Smile

What's the "official" OUT for activating the 5,38MHz on Panasonic MSX2+? The first one in this thread or OUT 65,8: OUT 64,0? Both can be found on the internet...

Maybe there's also a way to patch Aleste 2 so it can run on R800 with MSX-MUSIC or a program (RunIt or RMSX?) for MSX turbo R which checks if the MSX-MUSIC is accessed too fast by R800 and will slow it down a little bit, so it still can take advantage of R800 without framedrops?

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