RT-11 doesn't recognize my 3.5" floppy

Charles charlesmorris800 at centurytel.net
Mon May 6 19:21:14 CDT 2019

Thanks... I have an RT-11XM pack with version 5.04, booted the system from 
that - and it does recognize the floppy!
Except that whoever built it didn't bother to include DU.SYS, just DUX.SYS. 

Now I just have to figure out how to update the old RT11SJ 5.01 that my TSX+ 
runs on top of, to a later version, without clobbering all my work building 
it :)
Guess I get to learn how to make an RT-11 bootable disk!

-----Original Message----- 
From: John Forecast
Sent: Monday, May 06, 2019 5:38 PM
To: Charles ; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: RT-11 doesn't recognize my 3.5" floppy

The release notes on bitsavers indicate that the RX33 was not supported 
until RT-11 V5.04.


> On May 6, 2019, at 6:20 PM, Charles via cctalk <cctalk at classiccmp.org> 
> 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

More information about the cctalk mailing list