13 Jan
2014
13 Jan
'14
2:36 a.m.
On 13/01/2014, at 11:55 AM, Chuck Guzis <cclist at sydex.com> wrote:
On 01/12/2014 05:23 PM, Terry Stewart wrote:
Chuck, on a kind of related subject, is all double sided 8" media suitable for double
density format? I have been meaning to send Terry some disks to copy the Panasonic boot
disk, but have not worked out if any of the media I have is suitable.
The boxes of NOS disks I have found so far are marked as "Hewlett Packard Double
Sided" and "Nashua FD-20 WP". Do you think that either of these would be
suitable?
Chris...
Chuck,
These Panasonic drives are double sided and 77 tracks, and the machine
write data in double density. I'm assuming this means MFM?
Yup, MFM--only a few early systems wrote in MMFM (e.g. Intel MDS)--and they were pretty
much sui generis--their scheme of address marks, etc. wasn't the same as another
vendor's MMFM (I think some HP systems used MMFM as well).
The so-called IBM System/3 double-density uses FM on the first track and MFM on the
remainder.
If you want, you can call it a 5.25" 1.2M drive in your BIOS, but tools such as
ImageDisk don't use the BIOS anyway--it's all direct port I/O.
The only gotcha to be aware of is that many 8" drives require +24VDC for their
positioners and the like. But then, you're a TRS-80 owner as well, right? So you
should be aware of that.