[Coco] Re: Floppy drive/OS9 issue

[Joel Ewy]

Andrew <keeper63 at cox.net> wrote:>... My education on OS-9 is very 
>limited, but my will to learn isn't. I have 10 years experience (geeze, 
>it doesn't seem that long) with Linux, so OS-9 shouldn't be too much of 
>an issue (actually, I wish "change directory" wasn't "chd" - I am 
>forever typing "cd" from *nix and DOS, and of course it is failing). But 
>it will take me a bit to learn - I didn't learn Linux overnight, and I 
>don't think OS-9 will be an exception.

  There are, or were, some utility packages you could get for OS-9 that  use UNIX-like command names and syntax.  Or maybe it's better to  just plunge in and make the mistakes on your way to learning it...
  
>Anyhow, in answer to a few things:
>
>- Joel Ewy:
>
>I am looking at the original drive that came out of my FD-501 system 
>when I replaced it with the drive from Ebay (the CHINON FZ-502). This 
>drive is a TEC FB-501, and it clearly has only the bottom head, not the 
>top head. According to my edition of Pocket PCRef, this drive is a >SSDD, 
>180 kb drive....
    
  Ah, I stand corrected.  Maybe what I was remembering was that  though some of the later drives were only single sided, only the first,  full-height drives were actually limited to 35 tracks.
  
>- Gene Heskett:
>
>... I looked at that original 
>cable, and I did notice that on both connectors (drive end) that PIN 12 
>on the first connector (closest to the end) is missing, and PIN 10 on 
>the second connector (closest to the disk controller pak) was missing.
>
    
  I didn't have a floppy cable pin diagram handy so I Googled to see  which signals corresponded to your missing teeth.  Before I found  a pin diagram I found the answer on this page:   http://users.digitalindigo.net/~techno/coco_floppy.html
 If I had  seen this before I posted my earlier reply I wouldn't have made the  mistake about double-sided drives!  Despite the fact that I almost  got a migraine from the background, it has quite good information on  CoCo floppies.
 It seems that Tandy sometimes used missing teeth as  drive select logic.  That's most likely what you have there.   Check out what he says if the graphics don't make you puke.  That  might help you decide how you want to go about constructing your new  cable.  I would agree with Gene that the better way is to use a  straight cable and use the drive select jumpers on the drive if  possible.  But I suspect that your problem in accessing the DS  drives is not a hardware issue.
    
  I also spotted this:
  http://www.swtpc.com/mholley/35disk/Disk.htm
  on a site dedicated to the SWTPC 6800 and 6809 computers (the 6809  versions could run OS-9), confirming some of what I said in one of my  earlier replies, especially about using 3.5" drives on the CoCo.   Though now that I refresh my memory about what you are trying to do, I  realize that this is really irrelevant to you.  Still, it's a nice  page, and worth a look.  It shows how to use modern 3.5" floppies  without drive select jumpers using a cable with a twist in it -- but  not the same way as on the PC!  And this one doesn't have the  nauseating background image.

  >...
>I think I have a few old PC cables I could use to pull IDC connectors 
>off of, and I have no problem making a cable - but I would personally 
>prefer to use new connectors. I have had some "sometimes" bad luck 
  >in reuse of connectors, sometimes they break on me. I would be willing
  >to give it another shot, though - better to try something old than munge >a new connector, I suppose.

  I try to avoid reusing connectors when I can, but am not above it when I get desperate.
  
  >...
>Something that I am trying to understand, though: Joel, you said that 
>RSDOS/Disk  BASIC was never updated to use double-sided drives. I >could have  sworn, though, that with the FD502 disk system this was
  >the case? I 
>had a friend that had such a system (before I got my FD502 controller 
  >to replace my bad FD501 controller), and I could have sworn that with 
  >the drive he had you could put in a double-sided floppy, issue a DRIVE 
  >1 command, and read/write the other side? Maybe I am just not 
  >remembering things right? I am wondering if my memory is faulty, or if 
  >its a hardware/software issue?

  You are remembering right.  I should have been more  specific.  I don't think Radio Shack ever released a version of  DECB that supported anything but 35-tracks and 1 side.  But there  were lots of patches floating around, and some of the 3rd party  manufacturers of floppy drive assemblies included their own DOS that  would work as you remember.   Your friend must have had such a  system.
  I have a Disto Super Controller and a couple Super Controller IIs that  came with patched Disk BASIC ROMs that support using the second side as  drive 1 (though they still only used 35 tracks).  There was also  OwlDOS, RGB DOS (which is still available) ADOS, one from Orion  Technologies here in Wichita (the name of which escapes me (sorry, Bren  Stockdale)), etc.  
    
  >...Maybe under OS-9 it is just a settings 
>issue, and perhaps Carey's images will take care of that in short order. 

  That would be my strong suspicion.

>...JCE