General Category > LisaList2
Another Prototype Lisa Card
stepleton:
In re the AppleNet card, I believe the attached image shows a more accurate description of what's going on around the network connector. You can see that the pinout of T1 threw me.
The pinouts of transformers T1 and T2 are still guesses---on the card they are mainly unmarked boxes with no ability to see inside. This evening I made measurements with an ohmmeter on the two AppleNet cards I own in order to figure out which pins were the centre taps. I'm basing my guesses on tiny differences in resistance, but this was remarkably consistent across both cards.
As Patrick noted, connections to pins 3,2 or 5,6 of the connector may need to be swapped, or perhaps even both pairs if the current arrangement puts the pulses upside-down on both sides. I'd like to hope that the it's not the case that a single pair needs flipping: if not, the plug has a nice rotational symmetry, and you can turn a crossover cable into a straight-through cable by flipping it upside down. (You would have to do something about the keying on the shell of the DIN connector, of course.)
The github repo with my schematic has been updated. There are one or two more things I'd like to check, so some additional updates may follow soon.
Unfortunately one of my AppleNet cards seems ill---it hangs during the boot ROM card test some of the time. The problem may be mechanical---it seems like sometimes it'll make it past the test if I flex the card during boot. I'm not certain of this, though.
blusnowkitty:
Here's something I just thought of: Has anyone tried booting their I/O and DMA (and maybe AppleNet?) cards in a Lisa 1, or at least a 2/5 with a 1 ROM? I'd be very interested to find out if all those cards are expecting something in the Lisa 1 ROM that was taken out for the Lisa 2/5 ROM and beyond.
stepleton:
Yes, my video was from a Lisa 1 :)
There is not much stuff in the cards' boot ROMs for a very different result, I don't think.
It might be interesting to see what it does when an AppleNet card is also installed. Perhaps it will wait for a test program to come in over the network. I will probably try this soon.
(edited to clarify which boot ROMs I meant.)
stepleton:
To update: it looks like nothing different happens when an AppleNet card is installed.
ried:
--- Quote from: stepleton on July 11, 2020, 07:47:14 pm ---This evening I removed the (soldered, with the VCC pin attached to an enormous fill that sucked away all the heat) ROM from the DMA test card (picture attached) and dumped it...
--- End quote ---
I'm glad you did dump that ROM from your DMA test card, Tom, because I acquired another example of one that is missing its ROM. It's also missing a 7417N and, oddly enough, it looks like both the EPROM and the 7417N were removed from the board by having their legs carefully cut. Or at least it appears that way, because the legs are still soldered to the board.
Also note the oversized resistors(?) at the top, and the telltale sign of heat. I wonder what was going on in that area?
Should I burn a 2716 and add both chips back to the board? Or does this look like it'd do ghastly things to an otherwise working Lisa?
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