Did anyone mod the PSX BIOS?
Did anyone mod the PSX BIOS?
Just a simple question im trying to do the same and just change images and sprites. I know that shadow attempted to reverse it.
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Yuri^CybdynVerified
- Cybdyn Systems
- Posts: 406
- Joined: Jan 13, 2012
- I am a: Embedded Developer (MCU & FPGA)
- PlayStation Model: 5502
- Location: Belarus (Minsk)
do you use dissasimbling of Bios code?
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Shadow
Verified - Admin / PSXDEV
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- PlayStation Model: H2000/5502
- Discord: Shadow^PSXDEV
I never modified the BIOS. I do have some source code of it, but I never reversed it. I do have reversed CAETLA code however.
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.
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.
I have the playstation BIOS of the SCPH101 and the POPStation BIOS used in the PSP emulator.
Both are version 4.5 except the popstation bios has the CD/Mem card/Boot Screen disabled, it goes straight to the playstation logo. Either im going to reverse the bios to ASM or im going to HEX Edit my changes into it.
My current plan is to watch the ram as i emulate both bios and note the differences and make my way back to the HEX.
If i can edit the bios with images or even change a color or two ill work on programming it to a chip and trying it into a real PSOne.
Both are version 4.5 except the popstation bios has the CD/Mem card/Boot Screen disabled, it goes straight to the playstation logo. Either im going to reverse the bios to ASM or im going to HEX Edit my changes into it.
My current plan is to watch the ram as i emulate both bios and note the differences and make my way back to the HEX.
If i can edit the bios with images or even change a color or two ill work on programming it to a chip and trying it into a real PSOne.
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Shadow Verified
- Admin / PSXDEV
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- PlayStation Model: H2000/5502
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That sounds to good to be true! If you can edit the boot sequence, colours, sound and even get it all back into assembly, it will open new doors for us 
I know that the popstation BIOS has the CD-ROM and Memory Card editor removed. I believe that they used this in the PS1 emulator for the PSP.
Tomorrow I will upload my BIOS collection and reply here letting you know.
It would be a good idea to make a new topic under the Input/Output topic for the PlayStation 1, and make it into a work-log so we can follow your work.
I know that the popstation BIOS has the CD-ROM and Memory Card editor removed. I believe that they used this in the PS1 emulator for the PSP.
Tomorrow I will upload my BIOS collection and reply here letting you know.
It would be a good idea to make a new topic under the Input/Output topic for the PlayStation 1, and make it into a work-log so we can follow your work.
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.
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.
I did a hex compair between the two files and i can basically see all the data in both files compaired to the instructions i just wish i knew what format the images were in. Most likely a format that can be pushed directly to the gpu
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Yuri^CybdynVerified
- Cybdyn Systems
- Posts: 406
- Joined: Jan 13, 2012
- I am a: Embedded Developer (MCU & FPGA)
- PlayStation Model: 5502
- Location: Belarus (Minsk)
PSIO can load our own "bios" or "os" withou original intro. but after i made all comand support in PSIO , it bacame not neccessary to use biso mod. only for chance logo in launch screen. but its realy - "PS logo" is just TMD file (3d), and some pirate games has own logo. it stores in first sectors of ISO file (from 4 to15 LBA, or like this).
also you need flash IC for new bios - cause orignal bios is just ROM (only read memory).
also you need flash IC for new bios - cause orignal bios is just ROM (only read memory).
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