Fast External Memory

[languer]

The 18F452 should have plenty of memory; and all the banks can be accessed linearly.

For 1024 x 32-bit (long) words; a 32K serial EEPROM (e.g. 25AA320) would do. They can be clocked up to 10MHz (all in the HW SPI) which should be more than needed.

If you strictly need RAM (not long-term storage) then a serial RAM (e.g. 23A640) should do. Again SPI interface at speeds up to 20MHz.

I still think you should have more than enough storage on an 18F452.