11 Jan
2012
11 Jan
'12
7:32 a.m.
Date: Tue, 10 Jan 2012 15:00:21 -0800 (PST)
From: Fred Cisin <cisin at xenosoft.com>
Subject: Re: Cromemco FDC
<snip>
Although most 1.2M drives can be configured for 80
track DOUBLE (NOT
"HIGH"!) density, it adds additional unnecessary variables. 1.2M is the
WRONG drive for that FDC port. It might be feasible to cable the 1.2 (or a
1.4M!) drive to the 8" port, but don't even try until you get the
"normal"
stuff working.
------
I hate to argue with you of all people, Fred, but what is your reasoning?
Why "DOUBLE (NOT "HIGH")" and why is 1.2M the "WRONG" drive
type?
IMHO it's the opposite: HIGH (NOT "DOUBLE") and 1.2M HD is the BEST choice
with a 16 or 64FDC.
From the controller's point of view a 1.2MB HD
drive/disk is
indistinguishable from an 8" DD drive/disk, and a number of us
are indeed
happily using 'normal' 360RPM 5.25" 1.2MB HD drives & diskettes and even
3.5" HD drives (set to rotate at 360RPM); the only mod needed is to switch
the pin 34 jumper from the PC standard /Disk Change to /Ready.
If by 80track/double density you actually mean 'quad' density, that's not
really supported although if the drive also rotated at 300RPM instead of 360
then I suppose you could use 1/2 of it as a 360K DD disk.
If you want to go to the trouble of making a 34<>50 pin adapter then you're
good to go; on the other hand, the nice thing about the FDCs is that they
have both 34 pin and 50 pin headers, so as long as you connect the /ready
signal to pin 34 of the 34-pin header you can put all 4 drives on the same
34-pin cable in any mix of 5.25DD, 5.25HD and 3.5HD .
As I've mentioned, for whatever reason (RPM, transfer rate, short
inter-sector gaps?) most people have far more trouble creating
Cromemco-readable 5.25"DD disks from an image on a PC than 5.25"HD (as 8")
versions (not to mention 'real' 8" drives); that's certainly been my
experience.
And of course you do get more than three times the capacity.
mike
11 Jan
11 Jan
8:44 a.m.
> Although most 1.2M drives can be configured for
80 track DOUBLE (NOT
> "HIGH"!) density, it adds additional unnecessary variables. 1.2M is the
> WRONG drive for that FDC port. It might be feasible to cable the 1.2 (or a
> 1.4M!) drive to the 8" port, but don't even try until you get the
"normal"
> stuff working.
On Wed, 11 Jan 2012, MikeS wrote:
I hate to argue with you of all people, Fred, but what
is your reasoning?
Why "DOUBLE (NOT "HIGH")" and why is 1.2M the "WRONG"
drive type?
IMHO it's the opposite: HIGH (NOT "DOUBLE") and 1.2M HD is the BEST choice
with a 16 or 64FDC.
I worded it quite badly!
I meant that a 1.2M drive is a poor choice to use for the Cromemco 5.25"
formats, as a substitute for his TM100, because, as you said, it is
really a small 8" drive instead.
It sounded like he was trying to use 1.2M drives for the 400K 5.25"
formats. That CAN be made to work, but introduces a few unnecessary
hassles.
From the controller's point of view a 1.2MB HD
drive/disk is
indistinguishable from an 8" DD drive/disk, and a number of us
are indeed
happily using 'normal' 360RPM 5.25" 1.2MB HD drives & diskettes and
even
3.5" HD drives (set to rotate at 360RPM); the only mod needed is to switch
the pin 34 jumper from the PC standard /Disk Change to /Ready. If by 80track/double density you actually mean
'quad' density, that's not
really supported although if the drive also rotated at 300RPM instead of 360
then I suppose you could use 1/2 of it as a 360K DD disk.
I have seen 800K "quad" disks from Cromemcos. (I detest the term "quad
density", since it is double density with more tracks, resulting in quad
CAPACITY, but not quad density on the tracks.)
If you want to go to the trouble of making a
34<>50 pin adapter then you're
good to go; on the other hand, the nice thing about the FDCs is that they
have both 34 pin and 50 pin headers, so as long as you connect the /ready
signal to pin 34 of the 34-pin header you can put all 4 drives on the same
34-pin cable in any mix of 5.25DD, 5.25HD and 3.5HD .
I had heard (incorrectly?) that the 34 pin connector was only configurable
for the 5.25" data transfer rates (125K, 250K) V the 50 pin connector
being configured for the 8" rates (250K, 500K) >
Is that completely wrong?
As I've mentioned, for whatever reason (RPM,
transfer rate, short
inter-sector gaps?) most people have far more trouble creating
Cromemco-readable 5.25"DD disks from an image on a PC than 5.25"HD (as
8")
versions (not to mention 'real' 8" drives); that's certainly been my
experience.
Yes, the Cromemco 5.25" formats do tend to be problematic.
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