messiah/magic pins info

[charlie_ps2]

Originally posted by Rattle
I'm not so sure about that charlie, if any of the points to the bios is disconnected I would guess that no games at all work. I haven't tried it but that would be logical.

/Rattle

Er - believe me. V can be disconnected when playing PS1 games and the video mode won't be changed. That's the basis of the so called PS1 Color Fix for Messiah 1 solutions on US v4 due to a bug in the PS2 BIOS..

[charlie_ps2]

Originally posted by jsmith385
Isn't there a clock/read signal between M-W? It seems silly to add an extra wire for a redundant output disable (i.e. the CE#).

Charlie_PS2 stated that the Messiah 1 (M1) drew about 1/4A to 1/2A IIRC. That seems to me like a lot of current. Maybe the M1 is overriding the databusses on the PS2?

Methinks jsmith385 is someone else who knows what's what!

I believe that Magic 2 overrides the data busses on the PS2; I also thought I'd said Magic 2 draws 1/4 - 1/2 ampere. I might have included Messiah 1 in the generalisation but subsequent research tells me that's not so. It's less than 1/4 amp sustained. It was a bit difficult to do and it fluctuated around 150 milliamps during its period of activity.

We reckoned that A clocked the CD/DVD Controller readouts and R clocked the BIOS. We mesaured their profile using a scope. So it's an informed assessment.

[eltejado]

Originally posted by charlie_ps2
As you might imagine, it's a bitmore complicated than that. For example, the V line on the Messiah is used to feed the video mode to the PS2 dependent on the type of game selected. The W wire on the Magic 2 is the readout of the disk type.

I'm sure that is not simple. V line on the messiah is used for psx color fix, if i install a messiah and connect all points except V, all work perfectly but "psx color fix" not work correctly? and this option is only for US ps2? then, we can install messiah on a europe ps2 without connect V point and it works without problems, or no?

reading forum and charlie_ps2 troubleshooting, i deduce that:
messiah:
A = Enable read/write cd/dvd databus
B, C, D, E, F, G, H, I = cd/dvd databus
M, N, O, P, Q, R, T, U = bios databus?
R = enable read/write bios databus?
V = PSX color fix (only for US ps2?)
W = Inform disk type (ooooops, this is on magic, w magic and w messiah isn't the same, sorry, but on messiah inform disk type too?)

then a question considers to me, non-swwap mods make a patch on bios and cd/dvd controler, but all is databus, as mods know are on offset to patch? it need an address bus no?


Sorry for my bad bad english, again.

P.D. = now i don't have here a ps2 to try things.

[MacDennis]

Originally posted by eltejado
then databus and address bus are the same pins on cd/dvd and bios??
and bios pins are bi-directional too?
if i understand, for read bios address bus, i need to pulled low "R" (messiah), and for read bios databus, i need to pulled low "W"?
if it's correct, and cd/dvd-bios bus are same as ide bus, for study and understand it, i can read info about ide bus?

thanks for your reply's.

P.D.=> sorry for my bad english.

Address bus is at different pins and are not required for correct operation of the mods. Adress bus is not used!

Messiah R = CE# = Chip Enable (read that a few times)
Messiah W = OE# = Output Enable (see above)

You need to Enable the bios chip to Output data. Read some ROM datasheets and you will get the picture.

But the Messiah and all other modchips don't control these pins, they only *monitor* these pins to patch BIOS data at the correct time. For the Messiah, these pins also serve as a clock.

Grtz,
Dennis