Tutorial written by : Geremia (on IRCnet)

Requirements:

* Flash that will not work: 27Cxxx, 28F, W29C/EE020, AE29F2008 (this is a W29C020 distributed by ASD)
* Flash that will work fine: any 29F 39F 49F, 020, 040 and 002

This because Am29F080B (the onboard xbox flash) have not a special write initializing sequence, it’s a normal 29/39/49F, so the write initializing sequence coded by evolutionx guys will work fine for all generic 29/39/49F of any size.

Hardware:

You have to solder 2 wires from the points indicated (WE and OE) to the respective pins of your homebrew flashrom (31 and 24)(and disconnect 24 from GND and 31 from 5v as previously indicated by your homebrew diagrams)

click image for full view

If you encounter problems during flashrom identifying or flash writing, I suggest to close the 2 jumpers in the red rectangles as shown here, this will add resistors in the circuit that will give exact 0v when signals are LOW, but is not essential.

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Software:

You have to edit evox.ini with information about your flashrom. It’s important to write the manufacturer code, device code and size.
I’ve successfully flashed 4 different flashrom, and my evox.ini looks like this

[…]
Flash = 0x01d5,"AMD - Am29F080B",0x100000
Flash = 0x04d5,"FUJITSU - MBM29F080A",0x100000
Flash = 0xadd5,"Hynix - HY29F080",0x100000
Flash = 0x20f1,"ST - M29F080A",0x100000
Flash = 0xbf61,"SST - 49LF020",0x40000
Flash = 0xbfb6,"SST - 39SF020",0x40000
Flash = 0x01a4,"AMD - Am29F040B",0x80000
Flash = 0xda0b,"Winbond - W49F002U",0x40000
Flash = 0xc236,"MACRONIX - MX29F022NTPC",0x40000
[…..]
Item "Flash BIOS",@1
[…]

As you can see, SST manufacturer code is “bf” and “b6” is device code for 39SF020, 40000 is 2Mbit in hex. You can find manufacturer and device code of your flash when you try to flash using evolutionx. If it says manufacturer 09 and device ID 00, it means that you bad soldered OE and WE, or your flash doesn’t understand the “read manufact and device code” and so reports the content of the first 2 bytes (for xbox bios are in fact 09 and 00).
Store some bioses in C:\bios\ (you can use 256K, 512K or 1MB bios image files, evox does the job anyway), go to settings and then flash bios, choose bios and if your flashrom ID correspond to one in the evox.ini, you’ll be able to flash.

If you like, now you can use your xbox as a flashrom programmer with the hot swap trick, but I suggest to make an enable/disable switch using Dysfunctions schematics to prevent xbox destroying.

Thanks to EvolutionX team for the great tool.