Sony XV-T550 demystified. Look here if you have one.

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By Lord_Zett

Paladin (807)

Lord_Zett's picture

26-05-2015, 21:47

finaly ppl gona find all msxes even those with out logo.

realy great work NYYRIKKI i like the using of my 550.

most tryout those settings in that adres of switching output

By enribar

Paladin (985)

enribar's picture

26-05-2015, 23:47

Also Victor JVC JX-T800 is a MSX macchine more or less

By wernerkai

Champion (357)

wernerkai's picture

27-05-2015, 01:03

By Piter Punk

Master (201)

Piter Punk's picture

27-05-2015, 02:26

enribar wrote:

Also Victor JVC JX-T800 is a MSX macchine more or less

From JVC:

JX-T800 have a Z80 and a V9958.
JX-T500 the board maybe have a Z80 and V99X8

I'll wait before someone pick, open and dump those two titlers before calling them MSX based. Having the almost the same I/O port assignments and run MSX games are a good tests (IMHO) to see that.

NYYRIKKI,

XV-J550 runs in 60HZ, not 50HZ can you provide where you make the changes in ROM to fix it, so we can have the japanese machines working, too.

What tests did you do to check the IO ports and SONY memory mapper addresses? I am having some troubles trying to do the same job on VW-KT300.

BTW, amazing job!

By NYYRIKKI

Enlighted (5270)

NYYRIKKI's picture

27-05-2015, 10:44

Piter Punk wrote:

XV-J550 runs in 60HZ, not 50HZ can you provide where you make the changes in ROM to fix it, so we can have the japanese machines working, too.

To change to 60Hz, put 0 to:
T550DSK.ROM offset #38F3
T550NOWIND.ROM offset #1465A

Quote:

What tests did you do to check the IO ports and SONY memory mapper addresses? I am having some troubles trying to do the same job on VW-KT300.

There is no quick guide to success, but steps needed are practically same for all devices:
- Figure out, how you can execute custom code on the system. This time I found this by inserting MSX game cartridge. Because I ended up to black screen instead of titling software, from there I knew that I managed to interfere the normal boot process.
- Figure out the memory layout by writing a test program.
- Dump all data that you can. (Remember that also RAM dump can be useful)
- Search the dumped data for any abnormal things. (Weird I/O ports used, data written to ROM addresses etc.) In memory space there must always exists some routine to access non-visible data.
- When you find somethings -> Investigate -> Test -> Fail -> Repeat. It is quite unlikely that you will cause any permanent damage even if you don't know exactly what you are doing.

By NYYRIKKI

Enlighted (5270)

NYYRIKKI's picture

27-05-2015, 14:12

PAC wrote:

NYYRIKKI, should the ROM from sony XV-T550 work on a real MSX computers?

No. There are few problems:
- Custom memory controller: Although Konami mapper is quite a close to this one, it can't handle big enough ROM's to handle both program and font ROMs.
- Video table: This keyboard replacement is not MSX keyboard compatible.
- Leds: This device has more leds than MSX computers.
- Video control: This video control is not compatible with NMS8280 or Sony super impose enabled MSX models.
- SRAM: MSX computers don't usually have SRAM or if they have, it is not used same way.

These are not big problems, but makes it impossible to run the software on MSX without modifications.

By Piter Punk

Master (201)

Piter Punk's picture

27-05-2015, 15:42

NYYRIKKI wrote:
Piter Punk wrote:

XV-J550 runs in 60HZ, not 50HZ can you provide where you make the changes in ROM to fix it, so we can have the japanese machines working, too.

To change to 60Hz, put 0 to:
T550DSK.ROM offset #38F3
T550NOWIND.ROM offset #1465A

Thanks!

NYYRIKKI wrote:

- Figure out, how you can execute custom code on the system. This time I found this by inserting MSX game cartridge. Because I ended up to black screen instead of titling software, from there I knew that I managed to interfere the normal boot process.
- Figure out the memory layout by writing a test program.
- Dump all data that you can. (Remember that also RAM dump can be useful)

By now we only run custom software by changing the system ROM. Tabajara dumped the ROM and we burn a new EPROM with the test programs. In VW-KT300 there is no cartridge slot. Dumping RAM is a bit harder, I don't have where to write it.

NYYRIKKI wrote:

- Search the dumped data for any abnormal things. (Weird I/O ports used, data written to ROM addresses etc.) In memory space there must always exists some routine to access non-visible data.
- When you find somethings -> Investigate -> Test -> Fail -> Repeat. It is quite unlikely that you will cause any permanent damage even if you don't know exactly what you are doing.

Well, so I am in the "right" track. The dumped "BIOS", reads data from switched ports (mainly 45h) and while mapping memory blocks to the slots pages, on every page selection, it writes some data to page 1/slot 3.3, and in some high addresses on page 3 (always RAM).

Thanks for your information!

By anonymous

incognito ergo sum (109)

anonymous's picture

27-05-2015, 17:18

Thank you NYYRIKKI. I wonder why Sony mounted the cartridge slot when theoretically it is not available inside. I mean, the normal procedure when you are a board manufacturer (or any product), is to avoid to assemble useless components (cost down).

BTW, yesterday I found an interesting web where it appear a list of some products based on the MSX hardware, look at the bottom table. If the information is true, it's remarkable the use of an MSX2 as entertainment system, in the airplane seats, with Konami games. Smile

http://www.venus.dti.ne.jp/~prince/lib/m1.htm

By mars2000you

Enlighted (5468)

mars2000you's picture

27-05-2015, 17:42

PAC wrote:

I wonder why Sony mounted the cartridge slot when theoretically it is not available inside. I mean, the normal procedure when you are a board manufacturer (or any product), is to avoid to assemble useless components (cost down).

Maybe to allow the use of a specific test cartridge, similar to the Philips MSX2 test cartridge :

http://msx.hansotten.com/index.php?page=philips-test-cartridges

By anonymous

incognito ergo sum (109)

anonymous's picture

27-05-2015, 18:52

Piter Punk wrote:

From JVC:

JX-T800 have a Z80 and a V9958.
JX-T500 the board maybe have a Z80 and V99X8

I'll wait before someone pick, open and dump those two titlers before calling them MSX based. Having the almost the same I/O port assignments and run MSX games are a good tests (IMHO) to see that.



Let me correct. It's illegible but the IC on the right of the JX-T500 is an V9938 or V9958. Comparing situation of the words printed, they match perfect.

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