V9938 programmers' guide

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Por Poltergeist

Champion (276)

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08-01-2011, 10:48

@SD_snatcher: It is not stated that the V9938 was build by Texas Instruments, but I do agree the sentence is cryptical, to say the least...

Por Ivan

Ascended (9226)

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08-01-2011, 11:47

Text from the book:

"...and the last VDP in the family, V9990, can be found in rare MSX-Turbo machines and in add-on cartridges."

There is no TurboR with V9990!

Por Eugeny_Brychkov

Paragon (1169)

Imagen del Eugeny_Brychkov

08-01-2011, 11:53

Text from the book:

"...and the last VDP in the family, V9990, can be found in rare MSX-Turbo machines and in add-on cartridges."

There is no TurboR with V9990!
I must admit that I never seen Turbo-R and do know nothing about its schematics. I thought it was built on V9990??? If not, which chip it uses? And can V9990 only be found in addon GFX cartridges?

Por Ivan

Ascended (9226)

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08-01-2011, 12:07

You have the answers here: The Ultimate MSX FAQ - GFX9000 section

Por RetroTechie

Paragon (1563)

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09-01-2011, 00:36

And can V9990 only be found in addon GFX cartridges?
AFAIK, yes. The Turbo-R uses the same V9958 that MSX2+ machines have, IMHO it's basically an MSX2+ with a fast 2nd CPU (R800) tacked onto it. And some minor improvements like built-in DOS2, system timer, MIDI for the GT, and more RAM than usual for Japanese machines. Which is why this machine has always been too expensive for the hardware it offered (talking about price here, not about the value it might have to its owners... Smile2 ).

Por Edwin

Paragon (1182)

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09-01-2011, 00:49

The turbo R *should* have had the v9990. Then it would probably have been a great deal more popular as a game machine and probably extended the commercial life of MSX quite a bit. But unfortunately, it was rushed.

Por Manuel

Ascended (17337)

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09-01-2011, 13:25

Well, it should have had the V9978, with full backward compatibility, to be more exact Tongue

Por Daemos

Paragon (1750)

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10-01-2011, 01:30

I have downloaded this guide and must say that it actually rewrites the original V9938 manual in human language. Together with the VDP guide on the msx assembly pages I may have obtained just enough info to actually start doing something with the VDP.
So all I can say is: Great Job!!

Offcourse I will try some things out as soon as possible at least the good documentation for beginners is available now

Por Daemos

Paragon (1750)

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22-01-2011, 18:56

I have used the manual and still use the manual on a regular basis having learned most of my VDP skills from it. Therefore I propably have beta tested it quite well. Because of this I have been able to find some minor and major errors which I will point out per page:

page 3, The V9990 has not been used in the Turbo-R (Everyone allready commented that though)

page 11, At VRAM, the tekst says "Vide Random Access Memory" should be "Video Random Access Memory"

page 13, Port description table is missing the ports functions.

page 14, at the Register 17 table, Auto increment function is described wrong. 0 enables auto increment, 1 disables it

page 16, at step2, Table says register 45. Should be register 14

page 69 and 85, register 36 and 37 table. All capital D's should be a capital S.

page 71 and 81, register 36 table right description. Source should be Destination

page 78, register 32 up to 35 tables + description. All capital S's should be capital D.

There. I really hope to have helped finding the mistakes. Looking forward for the V9958 Manual Wink

Por Eugeny_Brychkov

Paragon (1169)

Imagen del Eugeny_Brychkov

23-01-2011, 20:02

Thanks.
3. fixed
11. fixed
13. What exactly you want to see there?
14. fixed
16. fixed
69 and 85. Not sure. I did not try that, but tables earlier in the text and descriptions are aligned. No change.
71 and 81. Labels fixed, descriptions are also seem to be aligned. No change.
78. Descriptions fixed. They seem to be aligned. No change.

Well, If you'll take the registers table at page 22 as a reference, descriptions "S" and "D" are correct in the hardware commands section. Can you elaborate please?

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