Date   : Wed, 23 May 1990 20:01:42 GMT
From   : eru!luth!sunic!mcsun!unido!balu!tilmann%cosmo.UUCP@BLOOM-BEACON.MIT.EDU (Tilmann Reh)
Subject: floppy drive hardware

gary@cdthq (Gary Heston) writes:
> Nobody forbids that, and many 8" DD formats used 1K sectors. The problem
> is memory space for buffers. Most CP/M machines were squeezing hard to
> get things to fit and leave room for some applications programs, too.
> Doubling all the disc buffers would have been prohibitively expensive
> in terms of a scarce resource.

Well, at that point you should have a look at CP/M Plus (or other modern,
banked systems). We are talking about which format to choose NOW, not about
the reasons our grandfathers got choosing small sectors.
The 64180 system I use now leaves a TPA of 61.25 K (BDOS entry at F500), and
the new Z280 system I'm programming now has 62 K (BDOS at F800). I certainly
will reprogram the resident BDOS part to fit into 2 pages (instead of 6), so
my TPA will be 63 K (BDOS at FC00).
BTW, there are 256 K of system memory used for hashing and buffering, but this
has absolutely no influence on TPA size. That's what banks are for...
In fact, I don't see ANY REASON for using smaller sectors!

> BTW, the original floppy formats used 256 byte sectors, as I recall...

Sorry. The original floppy format was 8" SD with 26 128-byte sectors. That is
the reason why a 'logical record' is still 128 byte (not only with CP/M).

Tilmann Reh (also at home)