Does the Lisa have any serial port diags that use a loopback connector?
LisaTest?
Quote from: ried on December 25, 2025, 01:32:41 PMLisaTest?
Thanks!
I hope it uses a standard loop back
I have one of the loopback adapters. I think I uploaded a photo of it here?
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.
Here are a few examples of Apple's parallel (on the left) and serial (on the right) loop back connectors for reference.
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?
Quote from: bmwcyclist on January 05, 2026, 10:42:22 AMSo... 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.
QuoteAnd.. 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.
Makes sense! Thanks!