RT-11 doesn't recognize my 3.5" floppy

Douglas Taylor dj.taylor4 at comcast.net
Tue May 7 10:15:52 CDT 2019

Very interesting , now that you got it to work, what can you use it for?
Will it be an exchange media with PUTR?


On 5/6/2019 6:20 PM, Charles via cctalk wrote:
> I have installed an RQDX3 and the M9058 distribution board in my 
> 11/23+. Since I don't have a 5.25" drive yet, I hooked up a 3.5" HD 
> (1.44 MB) drive from an old PC.
> After a struggle (which I documented on VCFED's DEC forum), I managed 
> to get all the jumpers and cables set correctly, and now my XXDP 
> diagnostics (ZRQA?? ... ZRQF??) recognize the drive as an RX33 (DU0:, 
> logical drive 0 since no hard disks are attached). It passes all the 
> tests, and I can INIT, DIR, and copy files to it using the limited OS 
> with the XXDP suite. The LED on the RQDX3 blinks once when the drive 
> is accessed. So far so good.
> But, when I boot the system (with RT-11SJ V5.01), it can't see the 
> drive at all. Attempts to access it result in the command hanging 
> indefinitely, the drive does not select, and the RQDX3 lamp flashes 
> rapidly. SHOW DEV:DU does say that the handler is installed for the 
> correct 172150, 154 location. However, SHOW DEV:DUn where n=[0..3] 
> displays two blank lines then back to the dot prompt.
> Is my version of RT-11 just too old to recognize an RX-33? If so, what 
> do I need to fix this? Presumably a later DU.SYS?
> Thanks for any help. Most of my experience is with PDP-8's so this is 
> slow going...
> -Charles

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