theon-1/6502

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THEON-1 97883489e1 changes

2025-12-03 19:10:16 +01:00

623 B

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CPU board

Components

CPU: W65C02
RAM: LY62256PL-5LL
ROM: AT28C64B
Register: 74HC377

Register

Address 0x5FFF/0b0101_1111_1111_1111
decode using 74HC20, 74HC00
b_{15},\dots,b_0
\overline E=\neg(b_0\land b_1\land b_2\land b_3)\land\neg(b_4\land b_5\land b_6\land b_7)\land\neg(b_8\land b_9\land b_{10}\land b_{11})\land\neg(b_{12}\land b_{14})\land (b_{13}\lor b_{15})

Timings

PHI2 target: 10MHz -> 100ns