TRS-80 Model 1 (was: Arty computers (was: Re: PDP-11/70 in Yates Center, KS)

Fred Cisin cisin at xenosoft.com
Fri Feb 2 16:42:11 CST 2007


>   such as
> sticking the directory of a diskette in the middle tracks of the
> diskette.  That kind of kludge doesn't translate well to a move to hard
> drives, and other large media.
>
> Mid-drive directories/FATs/GATs a "kludge?" Ah, no... There are specific
> (and very logical) reasons for that, and as long as you don't store files
> larger than half of the available storage (else you'd have a guaranteed
> fragmented file) what does it matter *where* you stick the directory info???

On drives that do not have a track 0 switch, the middle tracks are, indeed
faster to get to (step, pause, step, pause at something acceptable to
the step rate of the drive, for the calculated number of times).
BUT, on drives that have a track 0 switch, track 0 can be found
substantially faster (step,step,step,step,... until the switch says that
you are there, thereby stepping as fast as it will actually go with no
pauses).


How about OS/2?

> Not to mention: Why doesn't *every* OS stick the system files on the *last*
> tracks of the media? It would be much easier to re-sysgen said media
> without worrying about the OS kernel getting too large for the preallocated
> area of the disk/drive.

It usta be that there was a quite noticeable difference in reliability
between inner and outer tracks.  We did not WANT our directory structures
on less reliable tracks.


--
Grumpy Ol' Fred     		cisin at xenosoft.com



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