Groups | Search | Server Info | Login | Register

Groups > comp.sys.prime > #445

Re: X-Mode

Show all headers | View raw

On Friday, February 17, 2023 at 1:46:07 PM UTC-5, Dennis Boone wrote:
> > The EXL tapes are cartridge tapes. The tape units had a modification 
> > that allowed a blocksize larger than standard cartridge tapes. I had 
> > bought a tandberg tape unit with a modified block size. But it had 
> > a bad loading problem that tended to destroy the tapes (as reported 
> > by Don. It would have to be an EXL cartridge unit or one that could 
> > read 1040 byte records (as I remember the byte size).
> Ed, 
> 
> Are you _ABSOLUTELY SURE_ it was the tape units themselves, not the 
> controllers? Because on the 50-Series side, I'm pretty sure it was the 
> controllers that did the blocking magic. I've read PRIMOS distribution 
> tapes from QIC carts with unmodified drives, and done the deblocking of 
> this scheme. The 50-Series disks, after the early period, used 1040 
> _word_ disk sector size, with 1024 data words and 16 file system 
> overhead words as a header. PRIMOS, having grown up with half inch 
> 7-track and 9-track reel tapes, was accustomed to being having variable 
> on-tape block sizes as large as the available Ring-0 buffer could hold. 
> The easiest path to getting MAG* and other software to work was, I 
> presume, to get the controllers to present 512 fixed to the drive and 
> longer variable to the host. 
> 
> It seems extremely odd that a unix system would depend on such modified 
> drives and unusual (for unix) block size. 
> 
> There are known issues with the little rubber bands in the QIC carts, 
> for example, that also have known workarounds. And rubber wheels in the 
> drive train of such mechanisms also get gooey. Some brands worse than 
> others, and some folks have had this sort of wheel rebuilt. 
> 
> I still think it'd be worth at least talking to Chuck Guzis about these 
> tapes. If there's shareable 50-Series stuff on the tapes, I'd be 
> willing to help cover the cost. 
> 
> De

Prime was famous for convincing customers that the hardware they sold was somehow "enhanced", to prevent customers from using off-the-shelf products.  For example, their 8mm drive was way more expensive than buying one from Exabyte, but only the Prime 8mm drive would work on a Prime system.  However, I bought a regular 8mm drive on eBay, hooked it up to a PC SCSI controller, and could read old Prime 8mm tapes just fine.

I did a little searching and this article looked interesting.  Maybe this guy would be willing to help out with reading a Prime tape.  I'll be glad to share expenses too:

http://www.hp9825.com/html/qic_and_the_dead.html

Jim

Back to comp.sys.prime | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

X-Mode Edward Feustel <efeustel@feustel.us> - 2023-02-10 07:25 -0500
  Re: X-Mode kludge@panix.com (Scott Dorsey) - 2023-02-10 16:16 +0000
    Re: X-Mode drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-11 02:04 +0000
      Re: X-Mode ukctya <spsrich@gmail.com> - 2023-02-11 06:05 -0800
        Re: X-Mode drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-11 19:32 +0000
        Re: X-Mode drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-11 19:41 +0000
      Re: X-Mode Edward Feustel <efeustel@hughes.net> - 2023-02-11 10:56 -0500
        Re: X-Mode drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-11 19:01 +0000
          Re: X-Mode Edward Feustel <efeustel@hughes.net> - 2023-02-15 08:24 -0500
            Re: X-Mode drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-15 17:43 +0000
              Re: X-Mode Jim Wilcoxson <prirun@gmail.com> - 2023-02-16 05:14 -0800
                Re: X-Mode Edward Feustel <efeustel@feustel.us> - 2023-02-17 05:51 -0500
                Re: X-Mode ukctya <spsrich@gmail.com> - 2023-02-17 07:02 -0800
                Re: X-Mode drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-17 18:46 +0000
                Re: X-Mode Jim Wilcoxson <prirun@gmail.com> - 2023-02-18 05:56 -0800
                Re: X-Mode drb@ihatespam.msu.edu (Dennis Boone) - 2023-02-18 17:51 +0000
                Re: X-Mode Edward Feustel <efeustel@feustel.us> - 2023-02-24 05:51 -0500
                Re: X-Mode kludge@panix.com (Scott Dorsey) - 2023-02-18 15:08 +0000
  Re: X-Mode bill <bill.gunshannon@gmail.com> - 2023-02-11 19:05 -0500
    Re: X-Mode Edward Feustel <efeustel@hughes.net> - 2023-02-15 08:34 -0500
      Re: X-Mode bill <bill.gunshannon@gmail.com> - 2023-02-16 08:28 -0500
        Re: X-Mode Edward Feustel <efeustel@feustel.us> - 2023-02-17 05:55 -0500
          Re: X-Mode bill <bill.gunshannon@gmail.com> - 2023-02-17 12:39 -0500
            Re: X-Mode Edward Feustel <efeustel@feustel.us> - 2023-02-24 05:58 -0500

csiph-web