32768 color dual Shifter ST mod - schematics lost?

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32768 color dual Shifter ST mod - schematics lost?

Post by troed » Wed Oct 18, 2017 5:37 pm

I've just read through the well known textfile describing "how" to add a 2nd Shifter to a regular ST and gain not only STE color palette compatibility but increasing it all the way to 32768 colors:


Cool, I think, so I wanted to look into possibly doing it to one of my machines. However, there's no schematic with the textfile, only a parts list, and I've since seen others trying to hunt down the schematics (or the original designer, Barry Orlando) over the years without success.

Posting here in the hopes that somewhere someone has a copy of those schematics that could be scanned.


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Re: 32768 color dual Shifter ST mod - schematics lost?

Post by Smonson » Sat Oct 28, 2017 11:28 am

I think we could recreate equivalent schematics fairly easily from the BOM. Basically we are talking about a board that plugs into the shifter socket and connects two shifter ICs together, sharing all the control signals. The data bus will need to connected straight through while normal pixel data is being latched, but while CS is asserted, they would each see different bus lines.

I think most likely one of the shifters will be always wired up to the stock 9 colour bits, while the other shifter sees the 6 new bits, transposed into the positions of the original bits.

Then 3 new 5-bit DACs are made out of all those resistors.

Are you gonna build one? :)

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