HB-F1XD Japanese MSX2 - Replace V9938 with V9958?

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By NYYRIKKI

Enlighted (5900)

NYYRIKKI's picture

15-09-2012, 12:55

RetroTechie wrote:

Yes but I meant the opposite: 50 Hz default, and a hotkey for starting @ 60 Hz...

There are number of reasons why I made it to boot by default to 60Hz:

- The source computer is Japanese
- All commercial MSX2+ computers are Japanese
- The color encoder is NTSC
- Keyboard repeat rate & key scan interval is adjusted for 60Hz
- There is no 50Hz boot wait loop
- Most popular games (Konami) are meant to be played with 60Hz
- Land codes are Japanese (especially MSX1 software may expect Japan=60Hz)
etc.

How ever if you want to change the default behaviour, it is quite easy.
Current setup boot logo is in 60Hz, default is 60Hz and H-key down is 50Hz

If you want boot logo in 60Hz, default is 50Hz and H-key down is 60Hz then you should patch:
#3FF9 #C0 -> #C8

If you want boot logo in 50Hz, default is 50Hz and H-key down is 60Hz then you should patch:

#3FFB #02 -> #00
#2C63 #00 -> #02

By Colemu

Hero (535)

Colemu's picture

15-09-2012, 12:48

I think it's perfect as it is mate!
I prefer default of 60hz for the reasons you mention.

I only use the 50hz option when I want to play European 50hz games (Auf Monty plays way too fast in 60hz) oO

Really pleased I have the option to play them at the right speed now! Big smile

However, most of my best games are Japanese, and my computer is Japanese, so 60hz is best default....

By Colemu

Hero (535)

Colemu's picture

16-09-2012, 17:34

RetroTechie wrote:

The ROM upgrade wouldn't be the problem, you could use a 27C512 for that. And piggyback a 27C256, if you want full MSX2+ ROMs.

How do I do this?
As you know, I have a working 64k rom. How do I accomplish what you describe for the full msx2+ ROMs? Question

By Colemu

Hero (535)

Colemu's picture

16-09-2012, 19:24

Here is the full 64kb, modified ROM if anyone else wishes to use in their system:

MSX2+ ROM

By RetroTechie

Paragon (1563)

RetroTechie's picture

17-09-2012, 13:20

To piggyback a 27C256 on top of a 27C512 in this machine's 1 Mbit ROM socket, you'd have to:

1) Program the 27C256.
2) Bend sideways pin 1 (Vpp), 20 (/CE), 22 (/OE) and 27 (A14). And solder on top of a 27C512.
3) Pin 1 should be connected to Vcc (+5V, read: 3 cm. wire to pin 28).
4) Pin 20 (/CE) should be connected to the same slot select signal as the MSX2+ subrom. So if that subrom is in slot 3-1 (just an example), then you should connect EPROM pin 20 to /SLT31 signal.
5) Pin 22 should be connected to /CS12 signal.
6) Pin 27 should be connected to Z80 A14 or A15 (!) line. See here for a tip on how to fill the EPROM vs. wiring of its A14 pin (the socket pin isn't Z80's A14, since this address line comes from that other custom IC).

Connections to pins 20 and 22 can be swapped (/CS12 on pin 20, and /SLT3.. on pin 22), works the same but is less power-efficient (chip goes in activate state more often without being read).

The selection signals are already used in the machine, so no need to solder directly to the S-1985. See schematic from where to where a needed signal goes, follow those connections on the circuitboard to find a good place to pick it up (nearby the EPROM / easily solder-able point).

Note that those extra 2+ ROMs are not simply an optional 'cartridge': contents of at least subrom also depends on it. So when you add these ROMs, your 27C512 will need other contents too. You'd need an MSX2+ ROM set that does the boot logo & memory test without I/O port F4h present. Not sure if original 2+ ROMs would do that, or require modification. Time for another round of emulator ROM-testing... ;-)

By NYYRIKKI

Enlighted (5900)

NYYRIKKI's picture

17-09-2012, 15:08

Original MSX2+ SUB-ROM expects KANJI-ROM to be on same slot as SUB-ROM. This is easy to fix, but good to know if you plan to use original ROMs.

By OeiOeiVogeltje

Paragon (1402)

OeiOeiVogeltje's picture

17-09-2012, 16:44

thanks for that rom

By msxholder

Champion (394)

msxholder's picture

17-09-2012, 20:57

Have never ever seen an Kanji-rom in an slot or subslot.
So what's hapening ??

By NYYRIKKI

Enlighted (5900)

NYYRIKKI's picture

17-09-2012, 21:06

msxholder wrote:

Have never ever seen an Kanji-rom in an slot or subslot.
So what's hapening ??

Ok, yes... I meant KANJI BASIC ROM (CALL KANJI, CALL ANK, CALL CLS etc.)

By Colemu

Hero (535)

Colemu's picture

19-09-2012, 16:48

I fitted the V9958 according to Jipe's instructions and it works perfect! Smile

A BIG thank you to everyone who contributed/helped, I really appreciate it Big smile

Special thanks to NYYRIKKI and RetroTechie, couldn't have done it without your help my friends...

Now onto the next project, memory! LOL!

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