Re: EEROM's in place of EPROM's?

>Has anyone had experience with replacing their EPROM's with EEROM's so that
>they
>can be dynamically programmed via the test connector? I briefly looked
>into
>an EPROM emulator insted but if a game board has paging on the program
>memory,
>it becomes much more difficult. Does anyone know if there is an EEROM
>series
>is fairly similar (pinout and timing) to the 2764-2756 range of EPROMs?

Sure-- I built an Atari 2600 cartridge copier in high-school using the same
technique. The 2864 is almost a dead-on match for a 2764 EPROM or 6264
SRAM. Write timing is a little different between the EPROM and SRAM, but
otherwise they're pin compatible.

When you start going larger you really start looking at more "flash" based
chips and not the traditional "EEPROM". For all intents and purposes
they're really the same thing, but Flash are not generally byte-eraseable.

For development work/hacking if you can't use MAME I'd go for an EPROM
emulator first, then a Flash module second. EPROM emulators are usually
SRAM based and are really quick to load-- a decent-sized Flash can take
10-20 seconds to erase before you can even start programming.

If it's just a one-sy two-sy type thing I'd just snag a Dallas ('er... Maxim
now?) NVSRAM. Fast, reprogrammable, pretty-close to EPROM pinout. You can
use a SPDT switch to select either the R/W line for programming or just tie
it low for "read only" (EPROM) mode.

-Clay
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Received on Thu Feb 8 17:50:45 2001