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[sowa99]

Hello Guys.

Xbox 1 is old topic now but today I wanted to do something with it and I would like to share with it.

My idea is to put 1MB TSOP at 1.4 Xbox motherboard. I found A18 & A19 at motherboard (was funny because it's easy to find but I had to desolder MCPX from two motherboards ) and it seems to be activity there! I don't have osciloscope but there is quick 5V signal. Looks like MCPX is trying to read whole 20 adresses but it is able to read only 18 (because TSOP32 has only A0-A17).

So my idea is to put 512 or 1mb bios to bigger TSOP and solder it ( A18 and A19 too). I know that 4x256 will work for sure (my friend made 2x256 long long time ago ) but I'm not sure about 512k.

This is my question, will MCPX be able to read and load something bigger than 256k? I mean is this seurced by software (code inside mcpx) or hardware (this one seems to be easy to hack )?

 I will test it tomorrow anyway, but if here is someone who tried it, post it please, it will save my tiime

[kirky1991]

I'm not 100% with what you want to know.

But i know that a 1.0 (I Think a 1.0) has a 1mb TSOP. You Can flash a 1MB bios on it... I'm sure of it.

[xboxmods2977]

I would be interested if you get this to work. Also, Here is another idea to toss around. I was doing a little odd research myself along these lines and found that the ST M29F080A (1 mb/40 legs) found on 1.0/1.1 boards, in theory, could be upgraded to the ST M29F032D (4 mb/40 legs) chip.

I imagine that if a switch were wired in, you could effectively boot between 4 different 1 MB bios images! Or, using the traditional TSOP split diagrams, and then adding another switch, you could then boot from an assortment of 16 different 256k bioses, or 8 512k bioses!

This would be awesome. Not very practical, and no real reason to do it, but just the fact that it could be done is reason enough for me.  

EDIT: I just remembered. I recently had a 512k (29-wire) homebrew chip installed (which requires A18) and working in a 1.4 xbox. So, if the presence of A18 and the successful booting of a 512k bios are any indication, I am gonna say yes, your idea will work provided you can get A18 and A19 connected to the 1mb TSOP somehow.

Good luck! and keep me informed on your progress.

EDIT 2: I have just compared the data sheets of the TSOP32 and the TSOP40 and they only share a total of about 10 common pins. This means you will have to solder a wire to each leg on the 1mb TSOP and then solder those wires to the corresponding pads on the 1.4 board. This will not be easy.

[sowa99]

QUOTE

   I would be interested if you get this to work. Also, Here is another idea to toss around. I was doing a little odd research myself along these lines and found that the ST M29F080A (1 mb/40 legs) found on 1.0/1.1 boards, in theory, could be upgraded to the ST M29F032D (4 mb/40 legs) chip.

Yup, you're right, in 1.0/1.1 wouldn't be problem at all. if you have this chip in DIP40 you can aslo use it (soldering is eaiser). And then use some AVR to make switchig more profesional. Would be nice

QUOTE

EDIT: I just remembered. I recently had a 512k (29-wire) homebrew chip installed (which requires A18) and working in a 1.4 xbox. So, if the presence of A18 and the successful booting of a 512k bios are any indication, I am gonna say yes, your idea will work provided you can get A18 and A19 connected to the 1mb TSOP somehow.

What bios was on it? Homebrew 29 wire modchip is that same what a TSOP is so if you was able to boot some 512k bios (i.e. 5035 or some old X2, but what is important, bios must be 512 itself, can not be 256 sized to 512!), my idea will work.

QUOTE

EDIT 2: I have just compared the data sheets of the TSOP32 and the TSOP40 and they only share a total of about 10 common pins. This means you will have to solder a wire to each leg on the 1mb TSOP and then solder those wires to the corresponding pads on the 1.4 board. This will not be easy.

This is not problem, trust me I have soldered everything to the TSOP, now I have to solder it to MB, but I don't hve much of time

[xboxmods2977]

The bios on the chip was X2 5035, of course.