Friday, March 30, 2012

Back in the Saddle

As I mentioned in a previous post, work and other tasks have pretty much sidelined the Liber809 project.  However, I'm spending some time this weekend to rework the NitrOS-9 port based on several pieces of good news:
  1. The Liber809 board had stopped working for some inexplicable reason.  As it turns out, a piece of solder flake had found its way onto the trace from the Maxim DS1100 that leads to the Q clock on the 6809, leaving it perpetually grounded.  Needless to say, I'm going with solder masked boards from now on.
  2. The XEGS had timing issues with the firmware going into all-RAM mode.  The ANTIC was picking up writes to addresses outside of its range of $D000-$D7FF.  We have theories on this subtle timing problem, but reports from others that the 800XL and 1200XL worked fine in all-RAM mode has us thinking this is something unique to the XEGS.
Sloopy, a member of the AtariAge forums, sent over an Atari 800XL which I readily disassembled.  After some mucking around, the Liber809 board came up, and indeed worked well, even in all-RAM mode.  Slor's excellent Liber809 demo in the previous post came up just fine, sound and all.

With a solid, reliable Atari system running the Liber809 board, I can now focus on bringing up NitrOS-9 through DriveWire, which is how I envision the majority of folks will want to use the operating system.  So I've carved out some time this weekend to do just that.

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