8" floppy system needed to recover old game data

Allison ajp166 at bellatlantic.net
Sat Oct 8 12:48:53 CDT 2005


>
>Subject: Re: 8" floppy system needed to recover old game data
>   From: "Chuck Guzis" <cclist at sydex.com>
>   Date: Sat, 08 Oct 2005 10:30:15 -0700
>     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>On 10/8/2005 at 1:14 PM Barry Watzman wrote:
>
>>It's not a standard format, but it is actually possible to reliably get
>>nine sectors of 1024 bytes on each track of a double-density 8" disk.  I
>>supported such a format in all of the operating systems that I wrote for
>>the Zenith Z-100.  It gives you 1,419,264 bytes of formatted storage per
>>diskette.

That was not a particulary strange format, I'd seen it on a Morrow system
and the 765 even supported it.

Here's an oddball. 28sectors by 128 bytes single density 8". Seems with 
minor programming differnces of the 1771 for smaller gaps you could end up
with enough space at the end of a track for 2 more sectors or nearly 20k 
per disk. 

I had always found that 8" at 256k per side (128/26) single density was
a good medium and for DD 512k per side and DDDS at 1mb was clean and 
easy to live with. 

The CP/M world had an oddity that people using it may have noticed.  At 256k
(241k useable) was near the minimum for not feeling terribly cramped.  Smaller
was painful and always needed more drives and once you hit 512k or bigger 
life got easier. I found that for 8" DSDD (1meg) and two drives was a good 
working environment for serious work.  When I started with 5.25 floppies
life got hard (80k perdisk!) and didn't improve till 320/360k (40track 2sDD).
The prefered when I build a CP/M system with floppies these days is not less
than 720/780k (either 3.5" or 96tpi 5.25 DSDD) or the minimum equivelent in 
semiconductor (eeprom,flash or battery backedRAM).

Hope this sorta give a clue why people in the CP/M space tended to push for 
more space per disk.  Keep in mind that hard disks and controllers were 
expensive even past the mid 80s.


Allison



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