ULA Deconstruction 1

Back in 1996, when there was little hope of finding replacement HCS10017 ULAs for Oric, I began a deconstruction of the ULA's internals, using observed behaviour (the software inputs from memory, hardware outputs). This is the result of that process. There are some known minor discrepancies, so if you think there's a bug or inconsistency, you're probably right.

As of August 2018, I have reverse engineered the actual schematic from a decapped and photographed example of the real silicon and its corresponding verilog file, see here for more details

If you are searching for a replacement ULA for a broken Oric, look on eBay. They are now available from various sellers in Europe as NOS (new-old-stock) parts

Download

Documentation (original 1996 ZIP file of text and postscript/GIF diagrams, and 2018 complete PDF version) can be downloaded below.

Oric ULA Version 1

Oric/Atmos Unofficial ULA Guide 1.02 (PDF 133KB)