How to disassemlbe/edit PSX BIOS ?

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a4451137
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How to disassemlbe/edit PSX BIOS ?

Post by a4451137 » May 27th, 2014, 4:40 am

Hello
What tool use for disassemlbe PSX BIOS ?
How this BIOS is secured/packed ?

example.
How to change playstation logo boot ?
Image

In bios is checksum ?

Can I use IDA to disassemble BIOS ?

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Re: How to disassemlbe/edit PSX BIOS ?

Post by Shadow » May 27th, 2014, 6:08 am

Search for specific data type headers such as TIM, TMD and HMD using IDA. It wont be easy so good luck to you ;)
Development Console: SCPH-5502 with 8MB RAM, MM3 Modchip, PAL 60 Colour Modification (for NTSC), PSIO Switch Board, DB-9 breakout headers for both RGB and Serial output and an Xplorer with CAETLA 0.34.

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Re: How to disassemlbe/edit PSX BIOS ?

Post by a4451137 » May 27th, 2014, 6:21 am

Shadow wrote:Search for specific data type headers such as TIM, TMD and HMD using IDA. It wont be easy so good luck to you ;)

So many years and no one hack it :D
It is possibly to create my own menu ?
cybdyn wrote:my point is: you can make your own menu (psx-exe like) with the same pics (ripped) of background or even better!, then compile it from 80030000 start addres, and put it to 18000 to the new bios (without header 0x800).
bios shell is justa code - nothing special)))
How someone created modchip without sourcecode bios ?

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Re: How to disassemlbe/edit PSX BIOS ?

Post by Orion_ » May 27th, 2014, 7:19 am

I don't think this logo is as image data in the bios.
from what you can see in the vram during bios boot, you have a font loaded for the SONY text, and the middle logo might be a simple gradient polygon. (as it is animated remember)
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Re: How to disassemlbe/edit PSX BIOS ?

Post by a4451137 » May 28th, 2014, 12:42 am

But How modchip was created without bios source code ?

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Re: How to disassemlbe/edit PSX BIOS ?

Post by Shadow » May 28th, 2014, 12:54 am

The BIOS has got nothing to do with how modchips work (not including stealth). Modchips were made by hackers reverse engineering the system to know exactly what they had to do in order to get the PSX to boot copies.
Development Console: SCPH-5502 with 8MB RAM, MM3 Modchip, PAL 60 Colour Modification (for NTSC), PSIO Switch Board, DB-9 breakout headers for both RGB and Serial output and an Xplorer with CAETLA 0.34.

PlayStation Development PC: Windows 98 SE, Pentium 3 at 400MHz, 128MB SDRAM, DTL-H2000, DTL-H2010, DTL-H201A, DTL-S2020 (with 4GB SCSI-2 HDD), 21" Sony G420, CD-R burner, 3.25" and 5.25" Floppy Diskette Drives, ZIP 100 Diskette Drive and an IBM Model M keyboard.

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Re: How to disassemlbe/edit PSX BIOS ?

Post by Tommy » May 28th, 2014, 9:11 am

Shadow wrote:The BIOS has got nothing to do with how modchips work (not including stealth). Modchips were made by hackers reverse engineering the system to know exactly what they had to do in order to get the PSX to boot copies.
They spoof a signal between the CD drive and the outer hardware to make it look like an appropriate signal is on disc at an appropriate place, right? So the BIOS executes normally, believing the CD drive to have told it that a valid disc is inserted.
Orion_ wrote:... and the middle logo might be a simple gradient polygon. (as it is animated remember)
It definitely is: one of the emulators includes a note in either its manual or its graphics setup menu that you can enable rendering of quads as quads rather than as pairs of triangles to get slightly less subjective distortion but at the cost of the gradient on the startup logo not rendering correctly.
a4451137 wrote:So many years and no one hack it :D
It is possibly to create my own menu ?
Probably you'd get good mileage out of a standard R3000a disassembly and then differencing between the SCPH-1001 and SCPH-1002 BIOSes. The no-disc-inserted menu is entirely different in Europe from what it is in the US but obviously anything that game code may call is intentionally the same.

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Re: How to disassemlbe/edit PSX BIOS ?

Post by AmiDog » May 28th, 2014, 5:49 pm

a4451137 wrote:So many years and no one hack it :D
Well, nocash (martin korth) has written a complete BIOS clone for his emulator, so he has probably spent some time hacking the original BIOS.

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Re: How to disassemlbe/edit PSX BIOS ?

Post by a4451137 » May 29th, 2014, 4:46 am

IDA PRO support PSX BIOS image:

Image

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Re: How to disassemlbe/edit PSX BIOS ?

Post by org » January 14th, 2016, 11:50 pm

SCPH-1001 reversing:

https://github.com/ogamespec/psxdev/tree/master/reverse

IDA 6.5 project in SCPH1001.zip

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Re: How to disassemlbe/edit PSX BIOS ?

Post by Shadow » January 15th, 2016, 12:20 am

org wrote:SCPH-1001 reversing:

https://github.com/ogamespec/psxdev/tree/master/reverse

IDA 6.5 project in SCPH1001.zip
Very cool. Would be nice to get the complete source from Sony though :P
Development Console: SCPH-5502 with 8MB RAM, MM3 Modchip, PAL 60 Colour Modification (for NTSC), PSIO Switch Board, DB-9 breakout headers for both RGB and Serial output and an Xplorer with CAETLA 0.34.

PlayStation Development PC: Windows 98 SE, Pentium 3 at 400MHz, 128MB SDRAM, DTL-H2000, DTL-H2010, DTL-H201A, DTL-S2020 (with 4GB SCSI-2 HDD), 21" Sony G420, CD-R burner, 3.25" and 5.25" Floppy Diskette Drives, ZIP 100 Diskette Drive and an IBM Model M keyboard.

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Re: How to disassemlbe/edit PSX BIOS ?

Post by locarno » January 4th, 2019, 9:29 am

Shadow wrote:
January 15th, 2016, 12:20 am
org wrote:SCPH-1001 reversing:

https://github.com/ogamespec/psxdev/tree/master/reverse

IDA 6.5 project in SCPH1001.zip
Very cool. Would be nice to get the complete source from Sony though :P
Any update on this ? Sony released complete source or it leaked from somewhere ?

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Re: How to disassemlbe/edit PSX BIOS ?

Post by CodeAsm » January 23rd, 2019, 12:58 am

locarno wrote:
January 4th, 2019, 9:29 am
Shadow wrote:
January 15th, 2016, 12:20 am
org wrote:SCPH-1001 reversing:

https://github.com/ogamespec/psxdev/tree/master/reverse

IDA 6.5 project in SCPH1001.zip
Very cool. Would be nice to get the complete source from Sony though :P
Any update on this ? Sony released complete source or it leaked from somewhere ?
Last change on their wiki was in december I think, git was 2 months ago.
locarno wrote:
January 4th, 2019, 9:29 am
Sony released complete source or it leaked from somewhere ?
I hope you reread what that project is about, the meaning of the word "reverseing" is important here. ( https://en.wikipedia.org/wiki/Reverse_engineering )
Very intresting still tho, amazing what some people can figure out with IDA and programming knowledge. Hope more discoveries will be made.
Development Console: SCPH-102, unkown clone Modchip, PAL , FTDI board build into the case (microUSB) for Serial I/O.
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