Good EPROM Access Timings

[cubanismo]

Asking this in the programming subforum in hopes I don't get inundated with requests for things I don't want to do:  I got all set up to make some cartridges, and ordered some M27C160 chips and a lot of scrap cartridges to recycle from Ebay.  The operation was a success, and I now have a working cartridge on a PCB I slapped some 42-pin sockets on.  All good so far, so I went back to order more EPROMs from the same seller, and while looking for a larger lot, I noticed they have both -100F1 and -50F1 variants of the M27C160, corresponding to 100ns and 50ns access times in the specs apparently:

 

https://www.findchips.com/compare/M27C160-100F1--vs--M27C160-50F1

 

I had naively ordered the 100F1 chips the first time, and as mentioned, they work fine, but now I'm wondering if I lucked out and that was just a good batch, the game I burned used some relaxed memory timings, etc.  I looked through the technical reference manual, and by my calculations I'm OK either way I think:

 

-Jag runs at ~30Hz (round up to be safe)

-That's ~34.5ns per clock by my math

-Can't recall where, but I seem to recall reading that most games program/leave MEMCON1 at the default or at the least ask for 5-clock waits for ROM accesses

-34.5 * 5 = 172.5, well above 100ns.

 

Could someone check my work here before I go and order more chips that won't work if I want to burn myself a repro cart of some one-off game that wants super-fast access (I'm not making these for others, don't ask), or juice up the access speed for my own code?

[SCPCD]

The EEPROM interface use the IOSPEED parameter as the EEPROM is read/write from the GPIO interface.

If i remember correctly the register is configured it 6cycles.

Others mode are not working due to a bug in Jerry wich decode the GPIO range

 

 

[cubanismo]

To be clear, I'm talking about the EPROM (read-only chips when installed) containing the game data, not the serial EEPROM used for save game data.  Which are you referring to?

[SCPCD]

Oups, reading too fast

 

You will have enough time : it will work fine as all i known game set to 10cycles.