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Using just NAND gates requires too many of them. See http://www.neuroproductions.be/logic-lab/index.php?id=63191 for the unfinished work in getting a full chip to work.
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Building a prototype board internally
A prototype board is being built, here are the power connections
was built inside the Flash card..
707/009/16
It was very difficult to solder and the prototype did not work.
to the legs to the inverted small chips. As a result, this prototype failed to work.
Building the circuit on a breadboard externally
Components required
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10 sot to IC adaptors are being ordered so that the circuit can were obtained in addition to the 5 NAND gates. The circuit could now be bread-boarded and tested outside the Z88 card case.
The four signal and power lines can be seen connecting the card to the breadboard.
Oscilloscope Readings
This produced the signals required.
This trace shows the Flash chip being selected (/CE1) in 3nS.
The RAM (/CE) would be the same timings.
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The names of the signals on the scope are not all the same as shown in the circuit.
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Printed Circuit Board
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