8" floppy system needed to recover old game data

Tony Duell ard at p850ug1.demon.co.uk
Fri Oct 7 14:40:25 CDT 2005


> Think about the density of the data on the diskettes (this is not a
> comment meant as a defense for the poor quality of magnetic media, just
> part of the discussion) A 1.44M floppy diskette puts a lot more data in
> a smaller area.  The highest density 8" media I ever had was DSDD, or
> 720K on the big 8" surface.  That's a LOT larger disk and hence a much

It was actually closer to 1.2M. In fact the 1.2M IBM PC/AT format is 
almost exactly the same as a standard 8" format (it's the same data rate, 
same rotational speed, etc), the main difference being that the 8" drive 
has 77 cylinders, the 5.25" drive 80.

However, I would rather have less data on a disk (and thus have to 
buy/carry/store more floppies) and be able to read it back later, than 
cram as much as possible onto a disk and find it's unreadable a few days 
later.

> lower density. 
> 
> Plus, the world of computers today has a lot more room for
> junk/commodity media.  Anybody using floppy diskettes in 1976 had
> serious heavy-duty reasons for doing so.  And those diskettes were
> EXPENSIVE.  The disks you can get now at the Walgreens or a grocery
> store aren't the same.  Further, there's no market for a high quality

I've pointed out several tinms here that the first disks I bought for my 
TRS-80 Model 1 cost me \pounds 5.00 _each_ (not a box of 10 or anything 
like that).. That mackine put 88K on each disk (single sided, 35 
cylinders, FM (single desnity)). Point is, those disks are still readable 
20 years later. 

I would like to be able to pay a reasonable amount -- say \pounds 5.00 to 
\pounds 10.00 for a 3.5" disk with the same quality level. Because my 
data is worth a lot more than that.

> diskette, because 'high quality' customers have moved on to newer
> mediums.

Alas I have not. Not only because the newer drives are very poorly made 
and not properly documented, but also because most, if not all, of my 
machines can't use them. You try finding a DVD writer for a PERQ, or an 
HP41, or an HP9836, or....

> 
> I got handed a new shrinkwrapped box of 8" diskettes recently at work. 
> Finally everybody there is getting to know I am the person to hand stuff
> to.  I'm soon to get a nice desktop HP pen plotter, too.

Which model? 

I would love to find a 9862 with the original HP9810 interface module. 
But no chance of that (it would have to be local, there's no way I could 
afford to ship one anyway). Do far, the oddest pen plotter I've found is 
the 7470 Opt 003. That's an HPIL interface, it links up to the HP41, 
HP71, and HP75 calculators, amongst other machines. There's even an HP41 
ROM module to support it. It's rather strange seeing a handheld 
calculator driving a full-size A4 plotter.

The stranged HP plotter I own is not a pen plotter. It's the 7245A 
thermal printer/plotter. It's both a normal thermal printer _and_ a 
plotter -- in the latter mode it rolls the paper back and forth, moves 
the carriage across, and uses a special heater dot in the printhead to 
draw lines. Or so I am told. Mine doesn't work yet, which is why it's 
currently in a lot of bits on the bench.

There are a lot of manuals (user and service) for HP plotters on
http://www.hpmuseum.net , BTW. 

-tony



More information about the cctalk mailing list