Apple Lisa minimal card setup

[robin-fo]

Hi everyone, especially our Lisa experts here!

@AlexTheCat123 @warmech @RolandJuno

I'll hopefully soon test the Lisa Replica PCBs I've been assembling for a year or so now...

I have the following question: A Lisa can boot with the Motherboard and CPU card only – right? It will report an error obviously, but you'll have something on the screen at least. How is this possible if the soft power is controlled by the IO card? Do I simply have to switch on the PSU manually? I'm using the Lisa Breakout PCB for now. https://github.com/RolandJuno/Lisa_Breakout

Many thanks in advance,
Robin

 

[stepleton]

What am I, chopped liver? Sheesh.

I'll show you --- I'm going to march right upstairs, pull the card cage out of the 2/10 and yank out all but the CPU card and report back.

 

[stepleton]

The results are as follows:

With only a CPU board, the Lisa turns on immediately after power is applied, and the screen shows garbage:

(note: flashing images on the screen) https://photos.app.goo.gl/ss45GQ9gsFnigvCMA

With a CPU board and RAM populated, the Lisa still turns on immediately, showing an Error 41 on the CPU board as it continually redraws the screen. Retrace lines are visible.

(note: flashing images on the screen) https://photos.app.goo.gl/kgRQf9f5p2aYeNge6

YOU'RE WELCOME

 

[robin-fo]

What am I, chopped liver? Sheesh.

Sorry I forgot to mention you in the list of Lisa experts

Many thanks for checking, this is very kind of you!

So I need a working RAM card as well… I have two genuine ones in unknown condition, but with some signs of corrosion. I‘ll have to try them.

Composite output will work in that condition I guess?