21 Apr
2000
21 Apr
'00
3:52 p.m.
>>>> Forwarded message from Don Maslin
<donm(a)cts.com>
On Fri, 21 Apr 2000, Fred Cisin (XenoSoft) wrote:
On Fri, 21 Apr 2000, Don Maslin wrote:
In THIS case, due to sector size differences. But not ALWAYS. I have
seen non-CP/M disks with E5 where a CP/M directory would have been.
I don't recall running across that, but I'll be alert now.
what the
CP/M-86 would see on the MS-DOS format.
It gives you a big fat error message.
MS-DOS will give a big FAT :-) error message when
trying to read CP/M
(actually "Probable Non-DOS disk") because it is picky about what it
expects to see in the F.A.T.
Agreed.
Due to reserved tracks, on 8" double density,
CP/M's DIRectory will
fall AFTER the end of the MS-DOS directory, where the first file would
otherwise be likely to be. You're right that that would almost certainly
be content that would choke CP/M. But with very short files and large
clusters, and with sector interleave, it is entirely possible to have CP/M
looking at unused sectors.
Possible, but...
Both MS-DOS and CP/M will accept and assume
"empty" when encountering
a DIRectory (not the MS-DOS F.A.T.) sector of all E5. MOST MS-DOS formats
fill the empty directory sectors with 00, but not all. Some use E5, some
F6 with E5 every 32 bytes, ... What would CP/M-86 report for a directory
Rather like a CP/M directory that had its files deleted :)
sector of all 00? An MS-DOS format with a large
directory could easily
leave the END of the MS-DOS directory sectors where the first of the CP/M
directory sectors would be.
Agreed. I'll have to try the 00 bit and see what does actually
happen. I'll let you know.
I don't often see use of USER in CP/M disks.
Sometimes, but not often. I
think that it is more likely that they gave Sellam blank formatted
diskettes.
I wouldn't argue that. On the other hand, it would be prudent to check.
If he would mail one or more of the disks to me, I could examine them
and probably provide an answer.
- don
<< End forwarded message