The decoder chip works. It replaces 1/4 of the 74139 for the Z88 design.
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| Part No | Chip | Manufacture/ | Speed nS | Package | Drawing | mm | Price | ||
|---|---|---|---|---|---|---|---|---|---|
| Distributor | Max | Pad Pitch | Pad Width | Length | |||||
| 1741279 | SN74LVC1G139DCTR | Ti | <2.5 | SM8 | DCT | 0.65 | 0.3 | 4.25 | $ 0.69 |
| SN74LVC1G139DCUT Decoder | Ti / Farnell | <2.5 | VSSOP | DCU | 0.5 | 0.25 | 3.20 | £0.404 | |
| 1741279 | SN74LVC2G32QDCURQ1 | Ti | <2.5 | SM8 | DCT | 0.65 | 0.3 | 4.25 | $ 0.55 |
SN74LVC2G32DCTR OR Gate | Ti / Farnell | <2.5 | SSOP-8 | DCT | 0.65 | 0.30 | 4.25 | £0.377 | |
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Here are the chips that have been chosen:-
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Building the circuit on a breadboard externally
Components required
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1 SSOP8 IC adaptor was obtained in addition to the DUAL TWO-INPUT POSITIVE-OR GATE chip.
This circuit could now be bread-boarded and tested as a 1/4 139 as the other 3/4 of the chip is the same logic.
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