🚀 go-pugleaf

In article <987@cbmvax.cbmvax.cbm.UUCP> daveh@cbmvax.cbm.UUCP (Dave Haynie) writes:
>  The PC-AT
>drives can store a bit more than this, but they do it by formatting around
>135 tracks per side, which requires special high-density diskettes instead
>of the standard DS/DD diskettes that an 8250 could use.
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Dave Haynie	{caip,ihnp4,allegra,seismo}!cbmvax!daveh

It is my understanding that the AT's high density drive is 80 tracks per side, 
but due to a higher bit density, made possible by the higher coercivity 
medium used, they are able to squeeze fifteen 512 byte sectors per track. 
This leads to the following calculation:

			  2 sides 
			* 80 tracks per side 
			* 15 sectors per track 
			* 512 bytes per sector 
			__________________________ 
			1228800 bytes (1.2 megabytes).

By way of comparison, the standard PC/XT floppy format gives the following:

			  2 sides 
			* 40 tracks per side 
			* 9 sectors per track 
			* 512 bytes per sector 
			__________________________ 
			368640 bytes (360k).




						

Phil Staub
Tektronix, Inc.
ISI Engineering
P.O. Box 3500
Vancouver, Washington 98668
C1-904, (206) 253-5634
..tektronix!tekigm!phils