Advice for building a programmable cartridge

[abaudrand]

hi there,

What kind of programmable chip is good to make a SARA game for the 2600. the rom is 64Ko.

any advice ?

[GroovyBee]

I don't know of any combined EEPROM/RAM devices, so do you mean a microcontroller like the one at the heart of the Melody PCB? If you can solder SMD parts e.g. TQFPs and the like, you'll have lots more microcontroller choices. If you can handle devices like that then take a look at the LPCxxxx chips by NXP or the STM32xxx devices by ST. If you are stuck with 0.1" pitch devices then you might be able to get away with an ATMEGA device at 20Mhz, but I suspect its probably a little too slow at that clock rate.

 

For a "ready to go solution" you should be able to get a 64K flash, a narrow 0.3" wide SRAM and a PLD for address decoding on a 2600 cart sized PCB without too much difficulty.

[7800fan]

Isn't SARA chip just RAM?

[alex_79]

The problem is that the 2600 doesn't have the R/W line nor the phi2 clock signal on the cartridge port, so you can't just use a standard sram chip without designing an additional timing circuit. AFAIK, homebrews and hacks that need it, use either a melody board (with the arm processor simulating rom, ram and bankswitching) or old SARA chips (NOS or scavenged from original cartridges).

Edited January 23, 2017 by alex_79

[abaudrand]

ok thanks. just think its just not a matter of solder and play...