Firmware ROM of Panasonic MSX2/MSX2+ machines

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By sd_snatcher

Prophet (3480)

sd_snatcher's picture

07-05-2017, 01:12

luppie wrote:

I've also uploaded the FS-A1FX Dump, it can be downloaded here :

https://www.msxinfo.net/downloads/?did=234

In the FX only IC16 is present.

Thanks!

The only weird thing is that this file has the .hex extension, but in fact is a .bin raw binary dump.

By Piter Punk

Master (224)

Piter Punk's picture

07-05-2017, 03:32

sd_snatcher wrote:

I suspect that this "firmware dumper" dumps all the pages from the MegaROM that those machines have at the slot 3-3.

This is the same MegaROM mapper used in Turbo-R machines?

By sd_snatcher

Prophet (3480)

sd_snatcher's picture

07-05-2017, 03:39

Yes. The only difference is that it doesn't have the MainRAM pages in it, but only the ROMs and SRAM.

By RetroTechie

Paragon (1563)

RetroTechie's picture

15-05-2017, 04:12

Manuel wrote:

- how does the Panasonic mapper work exactly in these machines?

For starters: does the ROM mapper in the FS-A1WX switch 8 or 16 KB pages?

Quote:

Related to that: how are the ROMs from these IC's mapped into that mapper?

That's why a dump of the actual chips in an EPROM programmer (or transplant to megaROM cartridge or so) is the only proper way to produce a ROM dump imho. A straighforward and unambiguous way to obtain the data. And useful for repair ppl too.
For a software-only method: unless you know how the ROM is controlled (and thus how contents maps to programmer's point of view) there's just too many pitfalls:

  • Memory-mapped FDC registers (several bytes garbage instead of disk ROM contents)
  • ROM mappers that include contents of multiple ROM chips
  • Empty pages (not IC contents)
  • Mirrors
  • ROM/SRAM combo's (with contents variable depending on SRAM contents)
  • Non-obvious wiring of address lines (for example use A14 or A15 as highest address line with a 32KB ROM in 4000-BFFFh? A14 looks obvious, A15 is easier from programming point of view)

Extracting some blocks from IC contents for use on an emulator is easy. The other way around (emulator-formatted files -> file for burning/flashing into an IC), not so much because above info is missing. Empty space in a ROM should be included in a proper dump (such that file sizes match chip sizes). Empty pages in a mapper (no chip selected) should not be part of a dump.

luppie wrote:

I've also uploaded the FS-A1FX Dump, it can be downloaded here :

https://www.msxinfo.net/downloads/?did=234

In the FX only IC16 is present.

Thx, looks like a good dump! 1st half looks like graphic data (JIS1?). 2nd half has the usual bios/basic/subrom/kanji/diskROM/firmware that's often combined in a 1 Mbit ROM. Btw found this:

$ strings fsa1fx.hex | grep -i god
PRODUCED BY GOD ROOM

The kind of bs programmers leave behind in their code... LOL!

By Manuel

Ascended (18238)

Manuel's picture

15-05-2017, 07:34

Retrotechie, check the fs-a1wx dumps....

By luppie

Paladin (864)

luppie's picture

15-05-2017, 09:56

I have to make new dumps of the fs-a1wx, SD_Snatcher helped me find the correct settings for a reliable dump.
The string retrotechie is referring to is in the Cockpit Rom, since it isn't in my Custom FX Rom (that has Cockpit removed). Also it's followed by 'Hello'. I wonder if the Cockpit software has some kind of 'Easteregg' that will display this string.

By luppie

Paladin (864)

luppie's picture

15-05-2017, 21:21

By Manuel

Ascended (18238)

Manuel's picture

15-05-2017, 21:34

What I meant to say at Retrotechie is: check how these WX EPROM dumps are related to how they are seen by the software. Can you devise from the schematic how the mapping from EPROM is to hardware? As I have no clue.

What we used so far as a dump was a software dump that gives a totally different result. I don't have the dumping tool for that anymore (who does??), but the mapper is emulated of course (based on that software dump). See: https://github.com/openMSX/openMSX/blob/master/src/memory/Ro...
Of course, ideally, I'd also like to emulate the actual internal hardware that maps the ROMs to the different devices. But for that it helps if someone finds out how it actually works...

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