[DEV] - Flash Boot Rom PS1

[Xrider]

Hello,

I just told you about my project PS1 bios exchange.
I took a step in PCB design and physical testing on a PU-20 (Motherboard SCPH-7002)

The tests are conclusants.
Here are some photos:

Mounting:


Bios No $ Psx


Bios PSone (SCPH-100) JAP


Yes this last model will be mounted piggyback, the function "Dual bios" will be insured: 3207319737:

it's as big as a 50 cent coin: icon_study:

Some pictures :




Questions answers
What is the purpose of using a custom bios or Dev official?
=> Several reasons:
1 - PS1 jap have extra protection in their bios. With a bios EU or US, finished the zoning and hello the freezone (modchip for the region of Mechacon necessary)
2 - The bios No $ psx (Custom Bios) allows the boot of backups without chip, has advanced functions (Thanks No $ Cash)
3 - To make the dev or a future Bios Custom
4 - Just for fun, change the appearance of the original menu and others ...

To be reprogrammable without desoldering the Flash bios of the motherboard, I need help.

Would it be possible for one of you to modify a flasheur action replay by CD to reflash the eeprom?

I confirm, theoretically the pcb is compatible for re-programming via a CD.
Extract from the doc of the flash memory used on the circuit:
"devices write with a 2.7-3.6V power supply"

In other words, the address bus A19 which is not used on the BOOT ROM of the PS1 (PIN1 of the ROM mask boot) could be used to put the chip in writing state by putting it in the HIGH state on the PIN WE.

Thanks for your help

[danhans42]

The code to write to flash is fairly easy, you are just putting the commands to the correct addresses. You may be able to write to it by pulling WE low when flashing and wire everything else exactly the same, omitting the A19 pin.

The BIOS sits at 0xbfc00000 to 0xbfffffff so we could look at writing to those addresses rather than the usual extension ROM area. I have no idea what would happen if you try and write to the BIOS area in memory when it is in fact writable, and also given that the BIOS is in use at the time you are writing to it may cause issues..


Ideally though, I would like a PSone compatible version that allows it to be hooked up as an extension ROM using CE1 etc (ie AR/XP) rather than to replace the BIOS.

Good luck with your project, and if I could register my interest to possibly purchase a 2 units from you with respect to supporting it in NXFLASH?

Just be careful what flash part you choose to use.. as some are a little trickier to support. Personally I would recommend using an SST29EE020 as they are still easy to obtain in TSOP package and are easy to support code wise.

Feel free to drop me a PM if I can help. I was looking at your forum but unfortunately my French is appalling.

[Xrider]

Hello danhans42.

Thank you for your interest on my project.

It is with pleasure that I will sell you two units at a reduced price if you can update NxFlash to be able to flash them.
I wait my first PCB, it's will come in couple of weeks.

Ideally though, I would like a PSone compatible version that allows it to be hooked up as an extension ROM using CE1 etc (ie AR/XP) rather than to replace the BIOS.

Personally I would recommend using an SST29EE020 as they are still easy to obtain in TSOP package and are easy to support code wise.

Yes, but SST29EE020 is only 2 Megabit. it's ok for AR/XP and No$Cash rom, but it's to small for genuine BIOS (for change genuine bios JAP to other country for freezone with modchip)
I planned to use 4Megabit flash rom, the SST39VF040 TSOP.
It's very similar of SST29EE020 for flash them
All bios will be go inside (No SCPH-5903 )

Ideally though, I would like a PSone compatible version that allows it to be hooked up as an extension ROM using CE1 etc (ie AR/XP) rather than to replace the BIOS..

I will make more test for put the bios AR/XP, but with no GAL/PAL, probably doesn't work with no modification of there rom

Feel free to drop me a PM if I can help. I was looking at your forum but unfortunately my French is appalling.

No problem, i post the evolution here for you and again, thanks for your help

Xrider

[danhans42]

Hi,

The ST29EE and ST39 series are programmed differently. The 29 series is written as words (128/256byte)whereas the 39series series is written as a single byte so the flash algo will be slightly different.

The write commands are pretty much JEDEC standard, its just the order in which they work. If you look through the datasheets its quite easy to see in the xflash source code how it works.

I am currently looking to support the SST39 series in NXFLASH but the work is ongoing.

If you can let me know when you have the boards I will quite happily buy a few.. I have some ST39 in hand in TSOP32 but they are 256k so would also need the chips.

Great project mind you. Would love to see some proper BIOS mods for the original BIOS.

[paulm]

Can't you just use a bigger flash rom? E.g have room for 2 in your flash and a way to set the "active" one. Then when flashing only allow flashing the non active/loaded bios?

[Xrider]

If you can let me know when you have the boards I will quite happily buy a few.. I have some ST39 in hand in TSOP32 but they are 256k so would also need the chips.

danhans42 When I have received the circuits, you will be the first to know.

do you want a totally assembled card with a TSOP SST39VF040?

For me it's the best eeprom available on the market for this mod (512Ko)

Great project mind you. Would love to see some proper BIOS mods for the original BIOS.

Same

[danhans42]

You guys might wanna look here... Bios flasher supporting the 39F series.

https://www.obscuregamers.com/threads/bios-flasher.771/

[Xrider]

Hello,

It's working (no tested yet with cd for reflash) :












If you want one PCB, ask me (danhans42, i have reserved one for you )

[danhans42]

Hi xrider.

Great work. Look forward to testing! If you can drop me a PM with the details and I can send you payment for the module, and see if we can get it flashed in the console using the software from obscuregamers in the link.

[rama3]

I'm also interested in a populated board!
It'd be best with a 512kB chip, but 256kB is workable as well.
The No$Cash BIOS is pretty well compatible, but only if the Memory Card fast access option is turned fully off*.
I would want to use this 256k BIOS in my main machine, just because of the novelty ;p

*Any speedup of Memory Card operations is unfortunately breaking (even corrupting) saves.
For that reason it would be best to patch the No$Cash BIOS default parameters, so the speedup option defaults to off.
The defaults surely are a byte somewhere in the rom image.
If it isn't patched, users can still disable the option.
In that case the option will be saved onto Memory Card 0, and then this Memory Card needs to be present at boot time.

[Xrider]

Thanks for your interest rama3,

I will make lot of test before sell it.

But i don't forget you rama3...
Please send me your postal adresse in PM

[rama3]

Sure, and thanks

[LameGuy64]

That's a pretty sick BIOS ROM mod kit Xrider! I imagine this would be most useful in turning PsOnes into compact development units by storing a serial loader or a customized BIOS menu with serial loading capabilities into BIOS ROM.

[Armorant]

Hello, can't say that my old work will be helpfull to the @xrider or anyone else but here is the link to an old AG thread:
https://assemblergames.com/threads/ps1-bios-pcbs.68957/
Attachment shows how's it look. It's PSX-XBOO programmed (modchip is not needed but it still there, don't know why I didn't get rid of it a year ago).
Still, didn't try to reprogram my EEPROM with a modded CD that megavolt85 provide (sorry man), I were really out of console moding things for a year or more. I'm starting to getting back to it with new ideas (didn't know if they are useless or not but I'll try).

2.jpg

1.jpg

[Xrider]

Nice job Armorant,
My first revison was look like your pcb, but i would like preserve the genuine bios and add au dual bios fonction, and for that, i have make the new pcb
I use the same eeprom, the SST39VF040

[Armorant]

Thanks for Your words. PCB design above (for TSOP) has the dual BIOS capability, but I tried that only once a year ago with wrong BIOS writed. I wanted to use a 1001 as device 2 (PS1 BIOS ROM) and no$cash BIOS as device 0 (expantion ROM). They won't work cause back then no$cash BIOS has no capability to work as expantion ROM. Still can't find a version of no$cash BIOS that might work as expantion ROM.

[Squaresoft74]

Still can't find a version of no$cash BIOS that might work as expantion ROM.

There is one for Xplorer & Datel cheat devices using No$psx to create it or just get the attached file.

[Xrider]

I have try to burn it with expand.exe (thanks No$cash) with kHn compilation (thanks kHn) and it's work when :
WE is connected to SWRO
CE is connected to CS0.

It's work look like the Action replay.

I confirm the ID of the SST39VF040 it's "BF D7"

I think about it's possible to flash the original bios with this config, and after that we will switch the CE to CS2.

I try it a the next time

[megavolt85]

I confirm the ID of the SST39VF040 it's "BF D7"

test this

BIOS Flasher_0.2.7z

[Xrider]

I confirm the ID of the SST39VF040 it's "BF D7"

test this

BIOS Flasher_0.2.7z

Thank you for your help megavolt85
I have tried it and now it recognizes my eeprom.
I tried to burn the SCPH-7002 bios.
it take a long time (30mns) to burn 512Ko.
After that, not work (CSO and CS2 swapped = same thing).

But after burned the eeprom, i have dumped the eeprom.

You can maybe debug your software with this file :
http://www.delta-island.com/dump-bios-s ... r-burn.zip

Thanks