General Category > LisaList2
Twiggy Drives on eBay
sigma7:
Some more pics here:
https://www.flickr.com/photos/114907644@N04/albums/72177720300046948
D.Finni:
Thanks you two for the photos and schematics. Now it looks like the root difference is that the 1983 Lisa didn't have an IWM, but the Mac did. So the Twiggy Drive needed a new interface board to talk to the IWM on the Mac.
Does this sound right to you guys?
sigma7:
--- Quote from: D.Finni on June 25, 2022, 11:10:23 am ---... the 1983 Lisa didn't have an IWM ...
--- End quote ---
The Floppy Disk interface circuit on the Lisa 1 I/O board is most of a WM before Integration. (I don't know but it might even be "The" WM that was the basis for the integrated circuit.)
Improvements were made once it was integrated into a single part (such as the Mac version needing 3 instead of 5 bitslip FFs), but the core functionality is the same.
You are probably wondering if an adapter between the Mac and a stock Lisa Twiggy digital board is simply a matter of the 20 & 26 pin connectors. It may be as simple as that, but my recollection is there was a hiccup (per my thought that some sense signal(s) were inverted). The hiccup(s) might be tolerable if you're just experimenting.
edit: A glance at the schematic shows the Mac variant of the digital board has a 7905 regulator to make -5V from -12. The Lisa variant doesn't have this as the Lisa PSU supplied -5V; so your adapter (probably) needs to provide -5V too.
sigma7:
Lots of info about the IWM (and differences from the state machine made from discrete parts as in the Apple ][ and Lisa 1) to be had in the attachments to this post: https://lisalist2.com/lisalist1/0818.html
claunia:
For that price I make a laser floppy dumper, geez, people are nuts.
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