Ben Eater 6502 Kit — Day 10

in Project HOPElast year

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After I checked the CPU by hardcoding a NOP operation with 8 1kΩ resistors the next step is adding a ROM to for the future programs. Or better an EEPROM (electrical erasable read only memory). I already filled the ROM with NOP in Ben Eater 6502 Kit — Day 8. All I need to do is attach the ROM. Which is quite a bit of work:

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Placing the ROM and the NAND chip

All memory added to a computer need a memory management unit to generate the chip select signals o the correct chip is activated. This project uses a simple 4×2 NAND to do the job. Mind you, I have an 2×4 AND and 1×8 NAND as well to make it more sophisticated.

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Connect the chip select.

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Connect the first address bus line

The placement of the address lines on the AT28C256 is rather chaotic.

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Finished with the address lines

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Added the data lines

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Attached the Arduino

After attaching the ROM I tested the CPU. The result was as expected: After the reset sequence the CPU started execution at EAEA₁₆ as described in the video.

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Excellent work, what are you doing!, I congratulate you, and I am your admirer, although I do not know anything about this I find it fascinating! 😍