Re: Question about a FPGA cartridge/console in-between
Posted: Sun Jan 12, 2020 4:50 pm
Possibly. Really boils down to how fast you can handle the value that was written.
Forever ago, Memblers made a series of PIC-based softsynths ("Squeedo") that used two latches (one part of the PIC) to both capture the data and address buses during the write, and used the combination to determine what to do. By having the value latched externally, it didn't have to handle the write within 250ns (roughly the amount of time from when the NES drives the data bus to when it releases the data bus), but just had to finish handling the write before the next time the NES wrote to a register.
Forever ago, Memblers made a series of PIC-based softsynths ("Squeedo") that used two latches (one part of the PIC) to both capture the data and address buses during the write, and used the combination to determine what to do. By having the value latched externally, it didn't have to handle the write within 250ns (roughly the amount of time from when the NES drives the data bus to when it releases the data bus), but just had to finish handling the write before the next time the NES wrote to a register.