[rescue] Various machines for sale

[Maciej W. Rozycki]

On Thu, 9 Jan 2025, Dave McGuire via rescue wrote:

> >>     Neither.  Using IDE to control a floppy would be a challenge, as the
> >> whole "design" (using the word loosely!) of IDE is centered around the
> >> specific register layouts of an early Western Digital hard disk
> >> controller chipset.
> > 
> >   Which was done with ATAPI though, which in turn is just SCSI-over-IDE.
> 
>    ATAPI is not using IDE to control a floppy.  Using ATAPI (as you 
> stated) moves the SCSI protocol over the stunted IDE interface.

 Well, yes and no.  Still IDE data transfer commands are used to issue 
encapsulated commands and retrieve responses, and the DMA protocols (where 
used) are the same at the signal level.  But indeed a very limited subset 
of original IDE commands is used in this case.  Quoting from memory, so I 
may have missed something.  I have the original SFF specs somewhere for 
reference.

 Anyway as I say it is obvious from the SFF specs that you can control a 
removable magnetic disk over plain IDE, it's just that it was exceedingly 
rare in the field.  It's a plain C/H/S medium after all.  Other media such 
as CDs or tapes are a different matter and those indeed couldn't have been 
handled with the plain IDE command set.

  Maciej