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Version 1.1

A project log for Z80MiniFrame

Minicomputer based on Z80 microprocessor and designed with different cards and backplane bus

Tomeu CapóTomeu Capó 12/13/2019 at 16:461 Comment

In version 1.1 modify address decoding circuit and replace "OR" logic gates to 74138 TTL decoder to switch between RAM/ROM and devices like: PIO, UART, VDP and SOUND Generator.

Otherwise, design an external decoder to other devices put an OR gate between /EN internal decoder 138 and /IORQ and A6.

Discussions

Tomeu Capó wrote 02/05/2020 at 23:12 point

In this version also changed RESET circuit with 555, that have more stability than RC and Smith-Trigger NOT gate.

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