Cumulus Booted First Game
Posted by retromaster on November 24, 2010
I checked the Oric Bus lines with the oscilloscope and it seemed that there could be some signal integrity problems (overshoot, excessive oscillation, maybe even crosstalk). So I decided to remove the ribbon cable in between Cumulus and the Oric and connect Cumulus directly to the Oric by means of a makeshift male-male adapter.
The result was a huge improvement. Now I am able to boot Oric DOS disks without problems. Sedoric 1 disks also work (like the above L’Aigle d’Or). Unfortunately, Sedoric 3 still does not boot. It sometimes crashes with garbage on the screen, or other times, I get the Sedoric copyright boot text but also a warning that says “DOS is altered”, and it is stuck there. A commented disassembly of Sedoric 3 would have been very helpful at this stage… Anyway, it looks like I am getting quite close :).
Getting Sedoric 3 to boot is the first priority now. Once I get that to work, I might work on a new PCB design that gets rid of the separate UI daughterboard and puts everything on one compact, integrated board. To be able to do that, I’ll need to figure out if the cable can be left in place (solving the signal integrity issues in some other way), as that has a direct bearing on the mechanical properties of the board.