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How does a PlayStation 1 (PS1, PSX / PSone) Modchip work?

Posted: September 9th, 2012, 3:52 pm
by Shadow
How does a PSX Modchip work?
Whenever you put in a legitimate PlayStation black CD-ROM, you know it will work. Why? Well, in quick easy words, it has been pressed at a factory with a special code that is in the nanometers thin range near the center of the disc. This, is called the "Wobble Groove".

What does the 'Wobble' contain?
It contains a special string of letters which the PSX looks for on boot. The wobble does exactly as it is named. It 'Wobbles'. This causes 1's and 0's which make up the special code that the PSX looks and waits for on boot.

What are the special letters?
SCEE, SCEA or SCEI (depending on your region).
Original SCEE: 1 00110101 00, 1 00111101 00, 1 01011101 00, 1 01011101 00 = S C E E
Compressed SCEE: 100110101001001111010010101110 = SCEE
It is also now known that some special disc's (Yaroze boot discs) Sony made have SCEW.

Can I see the Modchip Assembly code?
Yes. You may see it over here.

So how does a Modchip help us?
Well, as we know, the signals consist of SCEE, SCEA, or SCEI characters. The modchip simply injects one of the SCEx characters (depending on the modchips code) into the needed wire at the correct time. This then tricks the CD-ROM controller that is has received the boot signature. This then allows the system to continue with its boot sequence so that you may happily play your game backup or homebrew code on the PlayStation 1.

Re: How does a PlayStation 1 (PS1, PSX / PSone) Modchip work

Posted: May 1st, 2016, 8:47 pm
by gwald
I've just emailed these guys asking if they can press wobble data.
I didn't say why I wanted to tho :D
Does SCEW work on all regions?