Any CPU needs RAM and ROM. If you are building a retro computer using a processor like the 8-bit 6502, you could use a RAM chip and an EEPROM chip, or you could use a Raspberry Pi Pico to emulate RAM and ROM for you!
My Clock Module:
https://www.youtube.com/watch?v=uH_x9LPTI-E
Ben Eater - Build a 6502-based computer from scratch: https://www.youtube.com/playlist?list=PLowKtXNTBypFbtuVMUVXNR0z1mu7dp7eH
Let Me Explain T-shirt: https://teespring.com/gary-explains-let-me-explain-2
Twitter: https://twitter.com/garyexplains
Instagram: https://www.instagram.com/garyexplains/
#garyexplains