Panasonic FS-A1 propietary firmware (DESKPAC) bypass by hardware modding. Can be done?

Supporter (7)

21-06-2017, 21:01

Hi, just adquired a MSX2 Panasonic FS-A1 black from JAUCE.com. As I have a MFR cart, it's very annoying to keep DEL key to bypass the firmware utilities included on this computer, as when you press F8 to go BASIC it reboots again, so to get the MM I have to wait about 3 resets.

It's there a way to disable that utilities? I will not use them in any way, as I don't speak japanese. Cutting some pin, a jumper, etc...

In later series of Panasonic computers they have a switch to permanently disable those utilities, but on the 1st ones is very frustrating.

Thank you in advance for your help!!!

Cheers,

Fireb0y

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Por f1r3b0y

Supporter (7)

22-06-2017, 01:32

Also, I have a Sony HB-F1 with same issue. The problem is that I don't want to remove as perhaps will lose the secret animation pressing Y and P while booting.

Thanks!

Por gdx

Enlighted (6429)

10-11-2017, 00:05

You need to replace the original 128kB ROM with another 64kB.

Original Rom contains in order: Main-ROM, Sub-ROM, an empty area of 16kB and the Firmware of 64kB.

I already changed the Rom in my Panasonic FS-A1. I used an eeprom W27C512-70.

Por f1r3b0y

Supporter (7)

29-04-2018, 22:22

Thanks a lot @gdx. Will buy some eeproms and test my old burner!!!

Por odaman68000

Rookie (25)

12-05-2018, 07:27

Or you can do it with simple hardware modification.
Just with 74LS10 logic IC, kills slot#3-2 and slot#3-3 signal.
But it should access to MSX-SYSTEM (S1985) chip, and its pins are very small, so it's very difficult to soldering.

Do you want to try this?

Por gdx

Enlighted (6429)

10-05-2021, 10:00

Just for the fun, I made a 66kB ROM (ASCII 16K mapper) that contents the firmware patched for users that have removed the internal firmware as me. This works also on some other Japanese MSX2.

Download: fs-a1_deskpac1-asc16.zip

For people that can replace the firmware fully, here is two examples of modification.

1/ Press Del key to run the firmware.

Replace "C8" by "C0" at 01002Bh (0402Bh in the fs-a1_deskpac1.rom file from OpenMSX).

2/ Press Select key to run the firmware.

Replace "3E 08 CD 41 01 E6 08 C8" by "3E 07 CD 41 01 CB 77 C0" at 010024h (04024h in the fs-a1_deskpac1.rom file from OpenMSX).

Por Guillian

Prophet (3529)

10-05-2021, 10:19

MFR SCC+ SD with recovery v1.14 or later, will automatically skip the internal firmware of different MSX models like HB-101, HB-201, FS-A1, FS-A1F, HB-F9S, HB-F1, HB-F1II, HB-F5, Hitachi MH-H3, Mitsubishi F120, Mitsubishi ML-G1, Philips NMS-8220, Yamaha_AX350II

Por gdx

Enlighted (6429)

11-05-2021, 10:34

It's really a nice function but I don't have MFR SCC+ SD and even if I had one, it's more convenient to change the firmware because it will no longer be annoying whatever my use.

Por Guillian

Prophet (3529)

11-05-2021, 11:42

The OP has a MegaFlashROM SCC+ SD, and since he asked a way to disable the firmware I think updating the recovery menu is the easier, faster and more secure way of doing it. He will no need to modify his computer, remove ICs, etc.

Por elkif0

Supporter (12)

16-02-2022, 19:15

I have one question: is full compatible the w27c512 with the original rom or i need modify some pins? unsolder ther and plug and play?

Por gdx

Enlighted (6429)

17-02-2022, 01:20

Yes, it is full pin compatible.

In the meantime, I found another method to bypass the firmware without remove the original ROM (but not tested yet).

To do this, you must write 23H to the address 0CBD8h before the firmware is executed. You can create a ROM for this or apply a small patch to the Disk-ROM of your flash card interface.