XTIDE controller now available

[Guy Sotomayor]

On Oct 5, 2009, at 3:00 PM, Phill Harvey-Smith wrote:

> Dave McGuire wrote:
>> I don't know where any supposed 520MB limit comes from; if someone  
>> can enlighten me there, I'd appreciate it.
>
> IIRC it's from the fact that most BIOSes can only deal with a 6 bit  
> sector number thus :
>
> 	AH = 02h
> 	AL = number of sectors to read (must be nonzero)
> 	CH = low eight bits of cylinder number
> 	CL = sector number 1-63 (bits 0-5)
> 	     high two bits of cylinder (bits 6-7, hard disk only)
> 	DH = head number
> 	DL = drive number (bit 7 set for hard disk)
> 	ES:BX -> data buffer
>

There were 3 of us (I was one...I can go I'd have to think about who  
the others were) at IBM that defined the mapping to ~512MB.  We knew  
at the time that this was a limit but we figured PCs would switch to  
an LBA format before we hit the limit...we were wrong.  :-)

TTFN - Guy