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

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Enlighted (6089)

NYYRIKKI's picture

24-05-2015, 19:42

Sony made XV-T550 as a video titler, but I had other plans for it and I now decided to share the information that I've collected.

If you are not into technical details so much, just take a look at these links to adapt your video titler to gaming console without even need for soldering iron:

(Video of my XV-T550 test setup.)

Support files

Mega flash ROM

Firmare update for Mega Flash ROM to play DSK-games also on XV-T550 (Based on version 02/06/2013 firmware)
Now you can flash DSK-files on MSX and play them also in your video titler.


Firmware update to use Nowind with XV-T550 (Based on version V4.3b)
- Insert Nowind on MSX and hold down "F"-key while booting.
- Type on host computer:
nwhostapp -f T550NOWIND.ROM
- Move the Nowind to XV-T550 and you are good to go.

Both of these updates only add support for XV-T550 and do not affect usage of these devices on standard MSX computers.

Sony XV-T550 technical details
Hacked By: NYYRIKKI (2015)

All information provided is gained by testing on unmodified XV-T550. All parts of it may not be complete or accurate. Generally typical MSX2 functionality is expected unless other vice stated.

General info:

Sony XV-T550 is Japanese MSX2 although you can't see it by looking at it. This is because video output is disabled during boot logo & other init and will only enabled after the Sony's custom titling program is started.

The controller works partly like MSX keyboard, but there is no enough pins connected to make MSX keyboard to work. Please take a look at service manual for details. PSG sound is delivered to controller already amplified. As I don't have the original controller, this part is not documented. Mouse port is compatible with MSX joystick port 1.

Most easy way to boot up this machine as MSX is to connect mouse port pins 1,2 and 9 together. This will cause it to drop to MSX-BASIC. Note how ever that screen output will be 60Hz, but the hardware can handle only 50Hz sync. If you use the patched firmwares, you don't need to do this.

"Font ROM" of this system contains both menu graphics and fonts. They are stored in to custom file system. I've extracted the files, if someone wants to take a look. Program ROM can be downloaded from Hans Otten page.

Printer port, VDP, PSG and PPI are mirrored also to I/O port = I/O port +4

Slot layout:

#0000-#7FFF Japanese MSX2 ROM
#8000-#FFFF Unused

External slot that can be found from between the two PCB's. The slot is lacking +12v and SUNDIN signals.


SLOT 3-0

#0000-#3FFF Japanese MSX2 SUB-ROM
#4000-#FFFF Unused

SLOT 3-1

#0000-#3FFF SRAM / Unused (See #4FFF)
#4000-#BFFF Sony mapped memory
#C000-#FFFF Unused (#FF)

#4FFF Switch address for memory range #4000-#5FFF
bit 7: 1 = Enable SRAM & Video output *
bit 6: ROM select. 0=Program ROM 1=FONT ROM
bit 5: FONT ROM: hi bit of mapper page. Program ROM: 1=disable memory (#FF)
bit 4: mapper page (not used by program ROM)
bits 0-3 mapper page

#6FFF Switch address for memory range #6000-#7FFF

#8FFF Switch address for memory range #8000-#9FFF

#AFFF Switch address for memory range #A000-#BFFF

*) Please note: bit7 is effective only in address #4FFF. To actually enable video output, you have to execute something from ROM. Any routine is fine. It is only important that CPU fetches an !INSTRUCTION! from ROM. When video output is enabled, SRAM can be disabled again without switching off video.

SLOT 3-2


SLOT 3-3

#0000-#FFFF 64K Memory mapper RAM *

*) Reading back memory mapper ports (#FC-#FF) works for bits 0-4. bits 5-7 return always 0

Special I/O ports:

I/O Port #70 controls both lights and video & sound:

BIT 7 = Input select (0=Input 1, 1=Input 2)
BIT 6 = Enable interrupts (?)

3 = OTHER (No lights, video troughput active)

I/O Port #71 can be used to read front panel key statuses:

BIT7=Input select

0 = Key down

Example program to set superimpose from front panel connectors:
10 COLOR ,0,0
30 OUT &H70,32+128

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By Manuel

Ascended (19676)

Manuel's picture

24-05-2015, 22:48

Fantastic! Smile What kind of things did you have to change in Nowind and MFR firmware to support this beast?

How does the start-up stuff work, with the disabled video? I guess it means there are custom ROMs then which write the #4FFF bit 7. (Which are custom, which are known?)

By msxholder

Champion (399)

msxholder's picture

24-05-2015, 23:20

Yeah nice indeed !!
Now Rebuilding My Video sketch titler XV-33F (z80,vram,mainram,9938 and rom)


Enlighted (6089)

NYYRIKKI's picture

25-05-2015, 07:51

Manuel wrote:

Fantastic! Smile What kind of things did you have to change in Nowind and MFR firmware to support this beast?

How does the start-up stuff work, with the disabled video?

The patch is same for both firmwares and is executed on boot time:

IF there exists Sony Video Titling software in slot 3-1 {
   - Switch screen output to 50Hz
   - Write #81 to #4FFF in slot 3-1 (Turn on SRAM)
   - Call RET instruction in slot 3-1 (Turn on Video output)
   - Write 1 to #4FFF in slot 3-1 (Turn off SRAM and disable Titling software bootcode)

Normally the video titling software is responsible for handling all the non standard stuff. (Pages 0-15 on mapper)

By Tabajara-Labs

Expert (95)

Tabajara-Labs's picture

25-05-2015, 23:34

I'm doing the same work with the XV-T777. Hope to publish info (and files) soon. It works more or less the same way.

By Lord_Zett

Paladin (807)

Lord_Zett's picture

26-05-2015, 07:16

Wow. More thans Nice!


Enlighted (6089)

NYYRIKKI's picture

26-05-2015, 08:52

Tabajara-Labs wrote:

I'm doing the same work with the XV-T777. Hope to publish info (and files) soon. It works more or less the same way.

Cool, yet another model that I've not even heard of... Smile There exists also Japanese versions (XV-J550 and XV-J777) that probably also share the same hardware except for the NTSC video stuff.

If you need help (ie. PS/2 keyboard driver). please send me a mail.

By o.geerdink

Hero (588)

o.geerdink's picture

26-05-2015, 10:42

Great job, have one with the original controller will try it with nowind

By Piter Punk

Master (232)

Piter Punk's picture

26-05-2015, 17:34

From SONY:

XV-J550 -> Japanese version of XV-T550
XV-J555 -> Dunno, didn't look it yet
XV-J770 -> MSX2 internals, like XV-T550 (this is the one that Tabajara have). Tabajara puts all the information that he could extract from this machine here:
XV-J777 -> Looks like J770 + Card reader

XV-T600 -> Not MSX related. Main processor is a 6502 and VDP is a RICOH VDP.

From Panasonic:

VW-KT300 -> MSX2+ internals. Custom "MSX-Engine" from NEC it doesn't have all pins and seems to have some kind of megarom mapper inside. Custom BIOS with only the stuff that this titler needs to boot. Can boot MSX1 BIOS but no further progress. I am trying to find how the pages from ROM are mapped on each slot-page.

By Tabajara-Labs

Expert (95)

Tabajara-Labs's picture

26-05-2015, 17:40

Piter, correcting you, I have the J777, not the 770.

By anonymous

incognito ergo sum (116)

anonymous's picture

26-05-2015, 21:17

I assume you already have this info about Panasonic VW-KT300 and Sony XV-J550

And, add one more video titler to the list, Victor JX-T500. Look at the picture of the main board, it features a V9958. Yes, it is impossible to read but compare with a bigger picture of the IC. I couldn't find better pictures, only more links like this where MSX word appears... In the previous one as well :P I don't know if the other IC is a Z80 but probably.

NYYRIKKI, should the ROM from sony XV-T550 work on a real MSX computers? Right now, I managed to buy a XV-T550 with mouse included, not sure which model because it is not the typical Sony Hit-Bit mouse :)

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