.Markku Reunanen.

Oric Microdisc and HxC

March 10th, 2012

There seems to be a lot of confusion concerning the use of an HxC floppy emulator together with an Oric. Some people got it to work, some not, and altogether the attempts have been more or less problematic. Here’s my two cents on the topic. I personally have an original Oric 3″ Microdisc, so I can’t comment on the Cumana related issues.

• Let’s start with the good news: it works! The bad news it’s rather quirky and not everything is as smooth as it could.
• The normal disk image converter will turn Oric dsk files into hfes, like it should.
• I used a twisted cable connected to the back of the case. With it the HxC can easily be installed as a slave unit, by using the “twisted cable drive B setting”. Works fine, but you can’t boot from it and if you don’t have proper system disks, you won’t get far.
• To set the HxC as the master drive things get a lot trickier. You need to tear open the Microdisc case, remove the floppy drive and set it to be the slave. By default dip switch 2 is on, but turn it off and switch 3 on. The HxC didn’t want to work with the normal drive A setting, but using the Amstrad primary drive setting it finally did.
• There’s the original Oric DOS (plus its improved versions), which is ok for old stuff. Modern programs, however, tend to run on Sedoric. The floppies formatted in one system or the other aren’t compatible. Some commands are different as well.
• The dsk images you’ll come across aren’t equal either. You’ll find 40 track double sided, 42 track double sided (Sedoric), 80 track two-sided images and so on. They do work fine with HxC, but in most cases can’t be written to floppies as is, since the original drive is single-sided.

My Microdisc came without a PSU and replacements are rare to say the least. Fortunately, it doesn’t take much to use a normal AT(X) power supply. You need to bypass the regulators and plug one Molex directly into the floppy drive. The controller needs to be powered, too, so screw the existing wires off and replace them with +12V and +5V. Be sure to check the coloring first! The wires coming from the small regulator are +12V and the bigger one produces +5V. On a standard Molex connector +12V is the yellow and +5V is the red wire. Not for the faint of heart 🙂 In theory the disc drive should power the computer over the ribbon cable, but in my case it didn’t.

Filed under: laitteet,retro