Some progress with my PDP-11/73 system

Allison ajp166 at
Tue Apr 10 10:31:30 CDT 2007

>Subject: Re: Some progress with my PDP-11/73 system
>   From: David Betz <dbetz at>
>   Date: Tue, 10 Apr 2007 08:58:01 -0400
>     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at>
>>> I soldered it back together but both drives still fail. At least  
>>> one of the drives spins up but then back down again.
>> That can happen if the heads are stuck against the end stop inside  
>> the drive.  There's a rubber bumper that goes sticky.  Alison  
>> posted more information about that just a few days ago.
>Yes, I saw those messages. At this point I'm not up for opening up  
>the drive to attempt a fix though. I guess if one of my good ones  
>stops working I may change my mind. Instead, I'm starting to look  
>into what is necessary for a minimal RT-11 bootable RX50 diskette.  
>Unfortunately, that's the only medium I have for moving things to the  
>hard drive on the PDP-11.

To boot a floppy under RT-11 is fairly easy.  You will need a bootable
disk, That is a copy of RT-11 with the bootdevice you plan to use configured.
It also must have the hard disk driver as well and basic utilities.  RT-11
fits on small devices (even tu58 256kB).

FYI: an option is to use TU-58 emulator on a PC and a serial line to
a PDP-11 as a fairly straight forward way to get stuff on a an -11
with blank media.  At the extreme the DD boot can be hand entered 
into uODT as its something like 30 words long.  I know I used to boot
a romless 11/23 that way.


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