Re: Old Apple code

[WULF@cip.physik.uni-stuttgart.de ()]

In <bn01865@pro-gumbo.cts.com> tgeer@pro-gumbo.cts.com writes:

> In <1993Feb22.032237.5895@microsoft.com>
> raymondc@microsoft.com (Raymond Chen) writes:
> >3. What is the meaning of track 0 sector 0 byte 0?
> 
> This byte indicates to the controller ROM code how many sectors to load into
> memory starting at location $800.  Normally this would contain a zero
> indicating that only track 0 sector 0 is to be loaded but in fact could be as
> large as 0F meaning that the entire first track is to be loaded.  Execution
> then jumps to $801, therefore sector 0 byte 0 is never executed.

Actually, this ability has been dropped. The //c boot code at least checks this
byte (it must be 1) and refuses to boot otherwise. I don't know this for sure,
but I can't remeber any program or operating system that used this feature.

- Wulf