Homebrew 6502 : It runs


An actual running computer with actual RAM and ROM! Memory decoding logic was painful. I added a quad 74HC00 NAND gate along with the 3 to 8 decoder. Code in ROM copies lots of NOPs into RAM beginning at $1000 and then JMPs in. It’s merrily NOPing along through RAM. Memory mapped as 32K RAM $0000 to $8000, 8K ROM at the other end $E000 to $FFFF which leaves a 20K hole for future I/O or whatever. Need to add proper clock next.

More homebrew 6502

Part 1 : 8-bit Nostalgia and powering up the 6502

Part 2 : It lives! Adding a temporary clock and the free run

Part 3 : Memory map, address decoding and adding a ROM

Part 4 : Building an EEPROM programmer

Part 5 : More address decoding, adding RAM

More to follow

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