Text 49, 53 rader
Skriven 2004-08-24 23:17:14 av George White (2:250/501.3)
     Kommentar till text 47 av Bill Birrell (2:25/200)
Ärende: [C] Code File Structure
===============================
Hi Bill,

On 23-Aug-04, Bill Birrell wrote to George White:


  >> Backups, no, not for this... It was bad enough working out the
  >> absolute, multi-sector file access (it _didn't_ work as
  >> advertised) and working round the discrepancies.

 BB> You mean you solved the "Linked cluster error" problem? Major
 BB> achievement! We had a guy over from the States to explain Cromix
 BB> file structure. Took him two whole days to start making sense to
 BB> us non-Californians. Then there were pages of notes... Even on 8"
 BB> Cromix the first sector was still single density. Damn! Off topic
 BB> again ... what C did you use

We only worked with CDOS, the CROMIX system was just used as a CDOS
multitasker, we didn't really use the CROMIX side at all. So I was
talking of the CDOS file problems. If yoy wanted to do a multi-sector
read starting at an absolute sector offset the only way to get it to
work was to do an absolute read of the starting sector and then to do
sequential reads (which read the first sector in again), and a similar
absolute write of the first sector and then sequential writes (again
allowing for the writing of the first sector twice). Following the
algorithms given in the CDOS manuals for access without the double
access of the first sector just resulted in corrupted files and limked
clusters :-(
We didn't use C at all, although we had the CROMEMCO CROMIX C for the
68000 side of the system. We were solely targeting Z80 CDOS systems...

  >> We didn't have that much direct contact with the suppliers. We did
  >> have our own systems though, one with a DPU running CROMIX and the
  >> other an early system with the Persci 8" drives (so old that even
  >> sales wouldn't ship it out!). The CROMIX system didn't have the
  >> cards needed to run product so they couldn't ship it out from
  >> under our noses, they just did that on the production systems.

 BB> A DPU (68000/Z80) was among those thrown out. Completely
 BB> functional, but not too much use on a Z2D. The black metal boxes
 BB> for Z2D  and HDD are still in a micropod in my bedroom if anybody
 BB> wants to collect them. Hard disks were incredibly noisy then

I've got a couple (I think, certainly one) of those "boat anchor" 19"
racks in my shed. Floppy only, and I don't know if they work now...
I've also got a 5 Meg HD (can't remember the details) for comparison
and the show the youngsters what they used to be like (enormous) with
a separate power supply. That _is_ dead!


George

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 * Origin: George's Country Point (2:250/501.3)