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Chip For Tight Mod

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#1 Brather


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Posted 19 November 2009 - 12:02 AM

Well after what 5 years im back in here this time looking to make a chip myself and on that spirit i went on the market (closet) of old pcs looking for a suitable candidate for the chip.

among a bunch of 386 pcs i located what appears to be an alternate to the so populat tightmod chip
this one is the Pm29F002t
its desc is as follows:

2 Megabit (256K X 8) 5.0 Volt-only CMOS Flash Memory
The Pm29F002 is a 2 Megabit, 5.0 Volt-only Flash Memory organized as 262,144 bytes of 8 bits each.
This device is designed to use a 5.0 Volt power supply to perform in-system programming, 12.0 Volt VPP power
supply for program and erase operation is not required. The device can be programmed in standard EPROM
programmers as well.
The 2 Megabit memory array is divided into five blocks of one 16 Kbytes, two 8 Kbytes, one 96 Kbytes, and
one 128 Kbytes for BIOS and parameters storage. The five blocks allow users to flexibly make chip erase or
block erase operation flexible. The block erase feature allows a particular block to be erased and reprogrammed
without affecting the data in other blocks. After the device performed chip erase or block erase operation, it can
be reprogrammed on a byte-by-byte basis.
The device has a standard microprocessor interface as well as JEDEC single-power-supply Flash compatible
pin-out and command set. The program operation of Pm29F002 is executed by issuing the program command
code into command register. The internal control logic automatically handles the programming voltage ramp-up
and timing. The erase operation of Pm29F002 is executed by issuing the chip erase or block erase command
code into command register. The internal control logic automatically handles the erase voltage ramp-up and
timing. The preprogramming on the array which has not been programmed is not required before the erase
operation. The device also features Data# Polling and Toggle Bit function, the end of program or erase operation
can be detected by Data# Polling of I/O7 or Toggle Bit of I/O6.
The device has an optional 16 Kbytes top or bottom boot block with a software lockout feature for data
security. The boot block can be used to store user secure code. When the lockout feature is enabled, the boot
block is permanently protected from being reprogrammed.
The Pm29F002 is manufactured on PMC’s 0.30 μm advanced nonvolatile technology, P-FLASH™. The
device is packaged in a 32-pin DIP and PLCC with access time of 55, 70 and 90 ns[/size][size=1]

its pinout is identical to the other. and seems to work. my xbox wont be here till friday but its something to look into.

it flashes with evox with no problems so once the xbox is here i'll test and report.

#2 obcd


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Posted 19 November 2009 - 09:55 AM

What can I say? A lot has happend in 5 years.

I am unsure what you mean with a tight modchip.
Maybe it's one of those things that need like 28 wires to function properly.

It will be a good soldering practice, but most people don't succeed in making something reliable when they need to connect 28 wires to small test points on a pcb. Don't understand me wrong, I am not saying that you won't be able to do the job.

Modern modchips use the LPC bus to interface to the xbox. It requires far less connections, and the xbox has a LPC debug header on the mobo. The only homebrew alternative I am aware about for that bus is the cheapmod. It's actually a special St flashchip that has an embedded LPC interface. It was used in low budget pc boards as bios flash chip.

Commercial modchip use a piece of programmable logic to interface a standard flash chip to the LPC bus. They usually divide the flashchip in multiple banks, and allow the selection of the boot bank.

Softmodding has become mature as well. The clock loop doesn't exist anymore, and the 137GB harddisk limit is gone as well. Pretty much everything that can be done with a modchip, can be done with a softmod as well.

Maybe you are just doing it for the challenge of doing it. In that case, ignore this writing.

I prefer to softmod my xboxes. I extract the xbox eeprom contents with an eeprom reader so that I can easily unlock the harddisk on an old pc with the xboxhdm package. There is no risk to damage things like with hotswapping, and you don't need an original exploitable game for which they ask astronomical prices if they now it's exploitable.
No matter how bad you mess things up, if you have a working lockable harddisk and the xbox eeprom.bin file, you can always make the system work again using this method. This can not be said from a game exploit or a hotswap, which is probably why this forum is still so much alive.


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