[Coco] Nitros9 wd1773 boot code

[Matthew D Stock]

On 7/13/2013 10:30 PM, Robert Gault wrote:
>
> If you look at the rb1773.asm code in the level1/modules directory you 
> will find comments about this section. There had been a problem (BLOB) 
> with booting named the Boot List Order Bug. You ought to be able to 
> read about it somewhere on RTSI.
> People used to think that you had to rearrange the module order but 
> someone found that the code above was bad. The is no need to 
> continuously send code to the controller in loop L123. The code around 
> L0111 is not needed.

Thanks, I'll take a look to understand it better.  I did find what I 
believe was a bug in my emulation.  This code is relying on the fact 
that the DRQ output will go low immediately (and thus initiate a HALT 
sequence) when the sector read/write command is given.  So essentially 
the Coco goes into HALT before starting that loop, and the polling isn't 
needed.

I can't be sure if it's all working or not now - I'm now able to get 
through most of the boot process, but it fails after "i2xto*W" - don't 
know if that's a problem with the nitros9 boot disk image I'm using, or 
another subtle emulator error.  Can anyone point me to the source code 
that documents these boot messages?
Thanks,
   -Matt