The Tyche ROM is a 64K QDOS ROM image, actually an update to QDOS for an unreleased QL successor system. It was developed by Jonathan Oakley, formerly of Sinclair, QJump and QView/Minerva fame on the QL scene.
The name ‘Tyche’ is apparently pronounced as “tie-chee”. I first became aware of this ROM in the early noughties, thanks to Simon N. Goodwin and Phoebus R. Dokos.
Tyche occupies 64K of ROM address space and includes some extensions to SuperBASIC. Phoebus was able to get it working on a QLay emulator, but not on QemuLator at the time anyway – instructions for QLay on my website, address below.
Now, David Westbury (author of Photon, etc) has turned his attention to the Tyche ROM and produced an uncommented disassembly and some notes about this interesting if little known version of the QL operating system.
He believes it was designed for a 68000 based QL successor, probably with a single floppy disc drive and a very similar architecture in terms of chipset. The Tyche ROM can be made to work on a QL with a standard older type disc interface, but apparently not on a QL with a Trumpcard, which is probably understandable as the Trumpcard bends the rules slightly when it comes to adding more than the design amount of RAM, for example.
David says that there is a lot of overlap of code with a JS ROM, albeit displaced, along with new code.
Download a Tyche ROM image, the disassembly and David’s notes from my website at http://www.dilwyn.me.uk/qlrom/index.html
Oh, and as for the name Tyche, I don’t know if this page correctly explains it, but it’s in keeping with the older Roman etc naming used for Jonathan Oakley and QView product naming, such as Minerva and Hermes: https://en.wikipedia.org/wiki/Tyche