Those cards use 28-pin 32KB (256kBit) parallel EPROMs. The original ones are likely cheap "one-time programmable (E)PROMs", which is the silicon of a UV erasable EPROM in a cheap plastic case without the quartz window. You can't reprogram those (well, some people managed to erase OTP EPROMs using a medical X-Ray device, but that causes damage to the chip, and they are toast after a couple of erasures), so you can just keep the original chips as backup chips.

Any 5V 28-pin DIP parallel EPROM/EEPROM/flash chip with at least 32K x 8 will work as replacement. Be careful with chips that have an "L" in the model number, as they are often "low-voltage" (i.e. 3.3V) only and might be destroyed by applying 5V. Winbond W27C256, Atmel 28C256 or Atmel 29C256 are possible flash chips. The TL866 is still very common, I didn't yet hear of a newer or cheaper flashing device that is able to program parallel ROM chips. There are modern cheaper programmers for serial flash chips, though.