Accessing a TK50 or TK70 from RT

Rod Smallwood rodsmallwood52 at
Sun Jun 12 14:49:08 CDT 2016

On 12/06/2016 19:18, js at wrote:
> On 6/12/2016 12:00 PM, Rod Smallwood wrote:
>> 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
>>  Rod
> Trim on long bottom posts, please.   Especially if there's nothing 
> interesting added at the bottom.
> - J.
  ..--.. I trimmed it to a one line answer. That's as short as I can go

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