General Category > LisaList2
Another Prototype Lisa Card
blusnowkitty:
https://www.ebay.com/itm/RARE-1981-APPLE-COMPUTERS-UNKNOWN-TEST-BOARD-PROTO-SK1158-02-6XX-XXX/303595454108
Any clues what this might be/have been? It's got a Synertek 6521a VIA, a 7405 hex inverter and a 74245 bus transceiver onboard, plus lots of empty space for other chips. Attached are the same pictures but mirrored for posterity since eBay pictures disappear after a while.
rayarachelian:
The a 7405 hex inverter and a 74245 are just used to enable access to the VIA. It looks like this has no ROM, so you can't boot off it.
Since it's only got a single 6521 it can only be a single parallel port. U1A-U6D aren't hooked up, so you'd need to wire wrap stuff there.
Edit: at first I wrote 6522, so yeah, it's a super early proto.
The 40 pin connector on the side likely connects almost all the pins of that VIA to the outside world.
I'd guess this proto is a very early parallel port test unit, before the Lisa was finalized as there's no ROM to identify it to the boot ROM, or to be able to boot from.
Which also means it won't be usable in any OS since it won't be recognized. I'd guess it has inherently a lot of historical value for what it is, but zero practical use in any current working Lisa.
stepleton:
It's nice that the seller provided those nice high-res images, since you could just clone it without much trouble...
D.Finni:
--- Quote from: stepleton on June 17, 2020, 04:53:56 pm ---since you could just clone it without much trouble...
--- End quote ---
Sure, but your result would still be "zero practical use in any current working Lisa." :P
stepleton:
--- Quote from: D.Finni on June 18, 2020, 09:01:57 pm ---Sure, but your result would still be "zero practical use in any current working Lisa." :P
--- End quote ---
I'm definitely going to stick to practical uses of my Apple Lisa, for sure :D
But in all seriousness, even though you can't boot from this card, you can probably still write some code on the Lisa side that talks to it somehow. It would depend on how old the thing was, and whether they'd changed the way the bus works. And, just for fun, you can do some eyeball reverse engineering from the photos already (along with page 3-9 of the hardware manual): unsurprisingly given the nature of the chip there, the fact that it uses the VPA and VMA pins says that this card uses the 6800-compatible bus signalling scheme. (The use of only eight address lines is another big clue, of course). I'd want to check all of the other lines, but if they were all good...
I wouldn't use it as the heart of my home automation setup, but you could if you really wanted to :)
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