OpenMSX runs a bit too slow

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Por jvidal

Rookie (18)

Imagen del jvidal

27-06-2021, 06:19

~mk~ wrote:

The Talent TPC-310 has a PAL/NTSC switch but that does not change the VDP frequency (which is hardcoded in the rom).
To get a standard video signal (PAL 50hz / NTSC 60hz), apart from using the switch, you have to invoke a bios call to change the VDP frequency.

From basic this would be as simple as:
VDP(10)=VDP(10)OR&h02 "switch to 50 hz"
VDP(10)=VDP(10)AND&hFD "switch to 60 hz"

If you are using a game cartridge, then you are stuck with the default frequency.
I've heard there is a modified main rom that can switch the frequency at boot time depending on the press of a key, although I've never seen it, nor have the modified roms.

You're right, you can change the VDP frequency in basic (it is reflected immediately in catapult's status bar (it shows 60FPS instead of 50), but if you insert a cart and reboot, then it reverts to 50hz.

BTW, isn't it easier to just set VDP(10)=0 in BASIC (instead of VDP(10) = VDP(10) AND &hFD)?

Por Manuel

Ascended (18068)

Imagen del Manuel

27-06-2021, 10:32

I didn't know there were multiple versions of this computer. Dumps for other versions are must welcome!

Por Manuel

Ascended (18068)

Imagen del Manuel

27-06-2021, 22:49

jvidal wrote:

Maybe the TPC-310 emulated by OpenMSX is an Argentine (PAL) Machine, not the export (NTSC) version..

Do you have more information about that export TPC-310? Exported to which countries?

Por ~mk~

Champion (301)

Imagen del ~mk~

28-06-2021, 01:47

jvidal wrote:

BTW, isn't it easier to just set VDP(10)=0 in BASIC (instead of VDP(10) = VDP(10) AND &hFD)?

Yes, but by doing that you are clearing other bits as well.
To change the frequency you are supposed to only change bit 1.
For details, check control register 9 details here.

I have seen a TPC-310 with 60hz video output. Yours and that one I've seen are probably standard TPC-310 originally designed for the Argentine market (PAL 50hz) that were modified to use with NTSC TVs.

Por jvidal

Rookie (18)

Imagen del jvidal

29-06-2021, 08:35

Manuel wrote:
jvidal wrote:

Maybe the TPC-310 emulated by OpenMSX is an Argentine (PAL) Machine, not the export (NTSC) version..

Do you have more information about that export TPC-310? Exported to which countries?

I still have My TPC-310, but it won't boot, so I can'd to much testing with it. I opned the case and everything seems normal (except the batteries were completly worn-out and dripping acid and the heatspreader on the VDP is kinda loose, but I don't see anything burned or exploding capacitors or anything like that. I remember samething wtitten on a piece of paper alonng the lines of 50 or 60 hz. I'd have to open it again to check

here are some pics:
https://servimg.com/view/20107521/17
this is the back plate, note the "chile" hadwritten sticker indicating this model was intended for use in chile only.

https://servimg.com/view/20107521/16
here are the roms. Note the "NTSC" lables on top of them, again confirming this model was intended for NTSC-capable countries.

https://servimg.com/view/20107521/18
And here's the VDP, labeled Yamaha 2701C, but I believe its a V9938.
The heat spreader has a label on it that read "VDP intermitete", which means "intermittend VDP" (probably meaning it was failing intermittenltly).
BTW, the MSX engine is A Yamaha s1985.

and, here's the back of the unit, confirmiong the existance of a 50/60hz switch
https://servimg.com/view/20107521/19

Por ducasp

Champion (454)

Imagen del ducasp

29-06-2021, 15:08

jvidal wrote:
Manuel wrote:
jvidal wrote:

Maybe the TPC-310 emulated by OpenMSX is an Argentine (PAL) Machine, not the export (NTSC) version..

Do you have more information about that export TPC-310? Exported to which countries?

I still have My TPC-310, but it won't boot, so I can'd to much testing with it. I opned the case and everything seems normal (except the batteries were completly worn-out and dripping acid and the heatspreader on the VDP is kinda loose, but I don't see anything burned or exploding capacitors or anything like that. I remember samething wtitten on a piece of paper alonng the lines of 50 or 60 hz. I'd have to open it again to check

here are some pics:
https://servimg.com/view/20107521/17
this is the back plate, note the "chile" hadwritten sticker indicating this model was intended for use in chile only.

https://servimg.com/view/20107521/16
here are the roms. Note the "NTSC" lables on top of them, again confirming this model was intended for NTSC-capable countries.

https://servimg.com/view/20107521/18
And here's the VDP, labeled Yamaha 2701C, but I believe its a V9938.
The heat spreader has a label on it that read "VDP intermitete", which means "intermittend VDP" (probably meaning it was failing intermittenltly).
BTW, the MSX engine is A Yamaha s1985.

and, here's the back of the unit, confirmiong the existance of a 50/60hz switch
https://servimg.com/view/20107521/19

It would be great if you were able to dump those ROMs... B-)

Por jvidal

Rookie (18)

Imagen del jvidal

29-06-2021, 19:50

I can't, my TPC-310 won't boot!!!! :'(
And I don't have a ROM Reader, either...

Por jvidal

Rookie (18)

Imagen del jvidal

30-06-2021, 04:40

One thing I noticed is that there are three 28-pin ROM chips on the Mobo,
-the MSX2 Main ROM (Bios+BASIC)
-The Accesories ROM (This machine has some built-in software, like a calculator, a clock and some other stuff)
-The Sub-ROM

But, the OpenMSX and MAME ROM sets for this machine also include the Turbo Basic ROM. I don't see any more ROM chips on the mobo, unless it is included in one of the three chips...

Por Manuel

Ascended (18068)

Imagen del Manuel

30-06-2021, 10:48

Probably no one ever made dumps from the ROM chips with an EPROM reader/writer. When that is done, I can adjust the openMSX configuration to use these instead.
When dumping from the MSX itself, you don't know in which chips the ROM content is organized and then makes sense to see them as separate ROMs.

Por Pencioner

Scribe (1462)

Imagen del Pencioner

30-06-2021, 11:14

I think one problem with dumping PROMs directly is that on hw level you can f.e. connect data or address lines differently, say, D0 from ROM to D8 on MSX bus and vice versa and then modify the ROM data accordingly as well swapping bits - this makes it work on the hardware but content of direct read and read via MSX would be different. IIRC there were some cases when it was donle like that (some IDE interface or so, don't remember exactly which device)

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