Resistors in an Arduino-based ROM-reader / SRAM-writer

I'm building a SNES ROM dumper with an Arduino and 74HC595 shift registers. (8-bit serial-in, parallel-out)
I'd like to write to SRAM as well.
I'm using the same design as this guy on the Arduino boards.

I'd appreciate your insight on the following points :

1. Should I use a resistor on each address line ? If so, how many ohms ?
(I looked up a 27C080's datasheet to have a reference, but it didn't mention maximum ratings as far as input current is concerned.)

2. Should I use a pullback [edit: pull-down] resistor on each data line ?

3. The SRAM writing feature means that each data line will also have to write to the cart, so a resistor is needed here too ?

4. What's the use of the cart /IRQ pin ?

The resistors are there to protect things when one inevitably inserts the cartridge slightly-wrong. But the actual ROM shouldn't take any input current on the address lines; you only really need to manage the RC time constant of (resistors you use) × (parasitic capacitance of everything on the far side of the resistor) ≤ (the speed at which the microcontroller changes address lines)

"pullback" ?

For dumping? Nothing. For games, it lets an external peripheral tell the SNES that something needs to be paid attention to now.

Does the resistor protect the ROM or the 74' chip ?


I meant "pull-down" resistor. For some reason, I couldn't edit my post before. Is it needed ?

The resistors are mostly there to protect outputs. So ... the 74' for the address bus, but the ROM for the data bus.

I don't see why you'd need pull-down resistors...

Thank you for those insightful answers!