ZX81+38 Build Help

[Fdiskitup]

But remember, I cut the traces, then reversed the process and put jumpers back in to replace the traces I cut.

[DeadTed]

Thanks for posting, I can confirm all my jumpers are set to default. I will do some additional measurements based on what you posted. I am powering the board through a regulated 5v power supply. Will post results soon.

[DeadTed]

Also does the clock have to be 3.23mhz as mine shows 3.25mhz but my original Sinclair shows 3.23mhz.

[1024MAK]

The official frequency is 3.25MHz. However, the ceramic resonators have a tolerance, so the actual frequency may be slightly different. A slightly different frequency makes no difference to the Z80. However if the frequency is too far off, some TVs/monitors may have trouble keeping a steady video image.

Mark

[DeadTed]

Ok, great I redid some measurements.

pin 16 is pulsing
pin17 is high
pin 18 is low
pin 19 is pulsing
pin 21 is pulsing
pin 22 is high
pin 24 is high
pin 25 is pulsing
pin 26 is high
pin 27 is pulsing
pin 28 is pulsing

A14 has activity
A15 is low
A0 - A6 has activity
A7 is low
A8 is low
A9 has activity
A10 has activity
A11 has activity
A12 has activity
A13 is low

Pin 29 is ground and Pin 11 is High