> Generating VERY precise timing and pulses, you need FPGA's or CPLD's
Back in the day, I managed to create a working RGH modchip based on Atmega8 (8 bit micro) running at 20 MHz with hand-crafted assembly code.
I named it RWH (Reset Witch Hack) and it was able to boot Xbox 360 Jasper in 1-2 minutes.
Old motherboards had a physical pad on the motherboard allowing for slowing down the CPU, so no i2c was required. I also have to connect the whole 8 bit POST bus to read the current value in one instruction.
PCB was made at home, and since AVR is 5V system, I used NPNs for voltage conversion (all values were inverted in the software).
Why? I didn't have money to buy the "real" CPLD modchip.
Rush and happiness when it first booted - priceless.
I still should have the source code for it somewhere on backup.
Back in the day, I managed to create a working RGH modchip based on Atmega8 (8 bit micro) running at 20 MHz with hand-crafted assembly code. I named it RWH (Reset Witch Hack) and it was able to boot Xbox 360 Jasper in 1-2 minutes. Old motherboards had a physical pad on the motherboard allowing for slowing down the CPU, so no i2c was required. I also have to connect the whole 8 bit POST bus to read the current value in one instruction.
PCB was made at home, and since AVR is 5V system, I used NPNs for voltage conversion (all values were inverted in the software).
Why? I didn't have money to buy the "real" CPLD modchip.
Rush and happiness when it first booted - priceless.
I still should have the source code for it somewhere on backup.
photos: https://gist.githubusercontent.com/JaCzekanski/c02ed11c30fac... https://gist.githubusercontent.com/JaCzekanski/c02ed11c30fac...