[Coco] RGB-DOS ROM identification

[Bruce W. Calkins]

> Hi gang,
> I have in my hardware collection an FD502 (26-3133) controller that has an 
> EPROM in it that has a label with RGB-DOS $0188DC on it.
>
> How can I identify what kind of hard drive this was used with?
>
> --
> Regards, Bob Devries, Dalby, Queensland, Australia


The OS-9 offset sets the start of the disk basic disks 0 through 255.  The 
space from the beginning of the disk to that offset is used for OS-9.  Any 
space above disk 255 is normally inaccessible.  There are work-a-rounds to 
using that higher space if it exists, but that is not yet your issue.



Short answer; any drive the same size or larger should work, (It has for me) 
although I not sure about head and track issues.  IIRC; they were only used 
for calculating the offset, and MFM drives did not use track and sector 
numbers at the computer OS level.



Bruce W.