Module Z80 CPU and MMU Z2 ( SBC Zeta v2 ) for RCBus systems
There are two versions of the module, which differ in the multiplexer used. Model A uses the 74HCT257, whilst model B uses the 74HCT253.
PLEASE NOTE! An experimental version was mistakenly made available in this repository; it contained an error whereby the /Er pin of the 74HCT670 chips was connected to ground instead of the /MEN signal. Anyone who has built a PCB with this error must make the necessary corrections!
| Component type | Reference | Description | Quantity |
|---|---|---|---|
| PCB | Z80 - Z2 MMU PCB - Version 1.0 | 1 | |
| Integrated Circuit | U1 | Z84C00xxPEG - Z80 CPU, CMOS, 40 pin DIP | 1 |
| Integrated Circuit | U2,U4 | 74HCT670 - 4x4bit register, 16 pin DIP | 2 |
| Integrated Circuit | U3* | 74HCT257 - 4x2-input multiplexer, 16 pin DIP model A | 1* |
| 74HCT253 - 2x4-input multiplexer, 16 pin DIP model B | 1* | ||
| Integrated Circuit | U5 | 74HCT74 - Dual D flip-flop, 14 pin DIP | 1 |
| Integrated Circuit | U6 | 74HCT138 - 3-to-8 line decoder, 16 pin DIP | 1 |
| Oscillator | X1 | 7.3728 MHz, CMOS oscillator, half can | 1 |
| Capacitor | C1 - C7 | 0.1 uF, 50V, MLCC, 2.5 mm pitch | 7 |
| Resistor Array | RN1,RN2 | 10 kohm, bussed, 5 pin SIP | 2 |
| Connector | S1 | 2x40 pin header, 2.54 mm pitch, angle | 1 |
| IC Socket | U1 | 40 pin DIP | 1 |
| IC Socket | U2-U4,U6 | 16 pin DIP | 4 |
| IC Socket | U5 | 14 pin DIP | 1 |
| IC Socket | X1 | 4 pin DIP for oscillator | 1 |
(*) - depending on the version selected
Gerber files for model A prepared for production at JLCPCB
Gerber files for model B prepared for production at JLCPCB
Copyright 2026 Tadeusz Pycio
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) .