Several comments on crashed drive in PDP-11/23

Allison ajp166 at
Sun Jun 19 23:06:44 CDT 2005

>Subject: Re: Several comments on crashed drive in PDP-11/23
>   From: "Jerome H. Fine" <jhfinexgs2 at>
>   Date: Sun, 19 Jun 2005 23:57:17 -0400
>     To: General Discussion: On-Topic and Off-Topic Posts <cctalk at>
> >Vintage Computer Festival wrote:
>>I downloaded and ran the TU58 simulator on my PC, then booted RT11 off
>>that.  I then created a bootable RT11 system disk and used the floppy to
>>boot.  Then I could mount blank images in the TU58 simulator and copy
>>files from the PDP11 to the PC.  Then you can use the PUTR utility to
>>extract files from the images on the PC into standard PC files.
>Jerome Fine replies:
>If you have a 5 1/4" RX50 floppy drive on a real DEC PDP-11,
>then it is probably much faster and easier to prepare
>the floppy on the PC with PUTR in the first place.  If
>the floppy is 8" and SSSD (RX01), then I understand that
>a PC can also have the same, but I don't know if PUTR
>can also handle 8" SSSD floppy media on the PC.  In any
>case, I have no experience with 8" floppy media on a PC.

It's possible to do RX01, but RX02 format is beyond what
the 765 based PC clopped controller can do. RX02 is not
the common style of DD format. To do SD format you need 
to do a fair amount of work and likely a older or even 
XT PC to insure the FM mode at 8" data rates is available.
Easier shot is the RX50 (SSDD, 96tpi).

>I am certainly NOT saying that a TU-58 is a bad solution,
>only that other solutions are often better if they are
>possible.  If the only way to start is with a TU-58, then
>it is certainly better than nothing.

Bob, of spare time gizmos did it right.  8051 with 2 256kB
rams to look like a TU58.  Save for one difference. The 
seek time is way faster!


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