Lisa Serial Loopback?

[bmwcyclist]

Does the Lisa have any serial port diags that use a loopback connector?

[ried]

LisaTest?

[bmwcyclist]

LisaTest?

Thanks!

I hope it uses a standard loop back

[compu_85]

I have one of the loopback adapters. I think I uploaded a photo of it here?

[stepleton]

Was that the one that involved Lisa expansion card? It looked pretty wild. If so, my recollection is that you posted a photo of it in the depths of the early COVID days.

[ried]

Here are a few examples of Apple's parallel (on the left) and serial (on the right) loop back connectors for reference.

[bmwcyclist]

Wow! very cool.

So... It seems odd that the traces on the left are not the same as the right...

And.. for the parallel, how is this better than a cable?

[patrick]

So... It seems odd that the traces on the left are not the same as the right...

IIRC one serial port uses RS-232 (COM) and the other RS-422 (AppleTalk). RS-422/485 is differential, it needs two wires for one signal line.

And.. for the parallel, how is this better than a cable?

It is more robust and faster to attach in the production line.

If you want to make your own, use wires.

[bmwcyclist]

Makes sense! Thanks!