Mini MicroBee update

I have the PC85 Microbee from the last post working now. Thanks to Ernest, who persevered in his assistance and identified a mistake in the ROM order, I was finally able to get a proper booting PC85B system. This allows double sized (16K – AKA 27128) ROMs and I’ve got a couple of additional games installed in “high” ROM spots above existing ROMs.

(The PC85 “core” (or top) board is the same between the A and B variants* so it’s a simple ROM swap to upgrade from one to the other)

From here on out, I’ll probably swap out the ROM that currently contains Viatel, as I have no use for that, and swap it for some additional games.

I am also beginning my research on how to make a clear acrylic case for this unit. I figure a nice transparent case will show off the beautiful innards of this system, and it is beautiful.

The purple is nail polish used to cover exposed copper. It’s as much part of the machine as anything else.

For anyone who is upgrading the PC85 from A to B, the ROMs need to go in the following sockets:

ROM NameIC Socket N°Lower ROM PAK Upper ROM PAK
ROM EIC 25PAK1 (Help)PAK9 (Free)
ROM FIC 24PAK2 (Spreadsheet)Reserved
ROM GIC 23PAK3 (Graphics)Reserved
ROM HIC 22PAK4 (Viatel)PAK12 (Free)
ROM IIC 27PAK5 (Shell/Menu)PAK13 (Free)

*Just to be especially exciting, there’s a MB8328-2 model that could theoretically be in a PC85 that needs a mod to be upgraded to 16k ROMs. Thankfully mine is a MB8328-4 which doesn’t have this disadvantage






One response to “Mini MicroBee update”

  1. […] model was working fine. I’d resurrected the PC85 and upgraded it to an 85b model complete with a bunch of embedded games. Now back to the last of the Microbees, the 16k early […]

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