Accessing a TK50 or TK70 from RT

Rod Smallwood rodsmallwood52 at
Sun Jun 12 12:00:27 CDT 2016

On 12/06/2016 16:19, Jerome H. Fine wrote:
> >Rod Smallwood wrote:
>>        Firstly one important fact that I did not know.  If you bulk 
>> erase a TK50 you can turn it into a TK70 tape with an INIT.
>>        Thank you I did not know that.
> A bulk erase was the first thing that seemed to be the solution
> since I had, fortunately, found a blank TK50 tape and was
> able to use it to both read and write in a TK70.  There was
> a long discussion, probably a decade ago, about CompacTape,
> supposedly just for the TK50, and CompacTapeII, supposedly
> just for the TK70.  From a Memorex internet site, probably over
> 10 years ago and long gone now, there was a table of all of the
> physical characteristics of CompacTape.  While the tapes for
> even higher density drives were different, the physical properties
> of CompacTape (I) and CompacTapeII were IDENTICAL!!!!
> So that also gave me the confidence to use the CompacTape
> media in the TK70 drives - which gave excellent results.
> Let us know if you are finally successful with the TK70 drives
> and tapes.
>>        Secondly I have made a little discovery.  We all know the 
>> tapes go sticky and attach themselves to guide rollers etc.
>>       Well its not always the tape.  I have three instances of tapes 
>> that would not feed or lace up where I got rid of the problem
>>       without doing anything to the tape at all.  In fact all 
>> subsequent tapes have had no problems.   It took 30 seconds and
>>       apart from taking the metal cover off the back off the drive I 
>> dismantled nothing.
>>       If I am right and can run a load of tapes through the drive. 
>> Then I'll say what I did. If I'm wrong then nobody will needlessly 
>> try my method.
>>       I will say its not cleaning the heads or the EOT sensors. You 
>> should do that any way.
> It would be appreciated if you would state what you did in any case.
> It is always helpful to know what has been tried and does not produce
> a result since it can be ignored in the future.
>>       Its clear the way to go is bulk erase TK50 tapes and then to 
>> use the TK70 drive and controller.
>>       Was there ever a UNIBUS TQK70 controller?
> I never used Unibus, so I never found out.  YES!!  Bulk
> erase is easy and does work well.
>>      RX02 and a RX01 (I have one of each and a spare chassis)
>>     I'll be back to them when this tape situation is sorted.
>>     I had got to the stage where I could get commands through to the 
>> drive electronics
> I have an RX02 around which I have not used in a while.  My
> preference, if I need the RX02 hardware is to use the DSD 880/30
> which has an RX03 drive which can also function as an RX02 and
> also reads and writes RX01 media as well.  My RX03 drive has
> been modified by placing a DPDT switch into the detection circuit
> for the single-sided vs double-sided sensors.  That way, I can use
> any RX02 floppy media as double-sided without having to punch
> the extra holes.  The DY.MAC device driver from V04.00 of RT-11
> contained extra code to support double-sided operation, but that
> code was no longer present with the V05.00 of DY.MAC when
> it was released in 1983.  So I added the code back and that
> made the DYX.SYS device driver under RT-11 able to support
> double-sided RX03 floppies.  However, the boot code is still
> a bit stupid and can't boot a monitor file which is partly at the
> end of side 1 and continues onto side 2.
>>    RD53 - Yes out of a bag of scrap drives I managed to get the 
>> remains of a bump stop out and replace it.
>>                 It produced one good drive which boots RT-11 every time.
> I still have a few RD53 drives around which I stopped using.
> I also converted a couple of Micropolis 1325 drives to
> RD53 drives by adding jumper R7.  I really don't use
> my PDP-11/83 very much since Ersatz-11 is really so
> much more convenient and my goal for RT-11 is only
> software bug fixes and enhancements.
> Jerome Fine
Thanks Jerome


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