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Floppy drives for an 11/73 with an RQDX3.

shevett

Experienced Member
Joined
Jan 28, 2020
Messages
58
Location
Boston, MA
I'm working on bringing an 11/73 up. It came with an RD52 and a TK50. The TK50 I'm pretty much giving up on. They're not worth the hassle.

It does not have an RX50 though - while that's obviously the 'proper' drive, I know you can use Teac FD55's as RX33's.

I have a Matsushita / Panasonic JU-455 1.2meg drive. Would that work?

I've read else-thread I'll need a no-twist floppy cable for it, that should be doable.

(Also, any advice on writing RT11 images to the floppies on a PCDOS machine would be appreciated.)

Thanks!
 
RX50 are double density 400KB - not 1.2MB High density, if you're looking for an easy way to boot the system, look at the tu58fs emulator and boot over a second DL type serial port and copy the files and bootstrap to the hard disk, if it is working - but don't expect a real RD52 to last forever... Third party SCSI controller and a SCSI-SD card board like ZuluSCSI is the way to go for long term use...
 
@Radix thanks for the info! My understanding is the Teac drives emulate an RX33, not an RX50, so that's fine. I will probably get an RX50 drive at some point anyway, but since I have the Panasonic drive sititng right here, just trying to see if I can use it.

The tu58fs emulator looks AMAZING. Very cool solution there, and worth trying - tape drive over serial port, magic!

Definitely not going to assume the RD52 will last forever. It's an ST506 interface, so I should be able to use any of the solid state emulators that are out there to pretend it's a real spinning disk.

But right now goal 1 is getting my KDJ11-B swapped out for something that isn't throwing cache errors (if anyone's watching my videos on this, it's been a journey :), and then booting a basic RT11 image. Maybe I'll just do that through tu58fs. A pretty cool idea.
 
@Radix thanks for the info! My understanding is the Teac drives emulate an RX33, not an RX50, so that's fine. I will probably get an RX50 drive at some point anyway, but since I have the Panasonic drive sititng right here, just trying to see if I can use it.

The tu58fs emulator looks AMAZING. Very cool solution there, and worth trying - tape drive over serial port, magic!

Definitely not going to assume the RD52 will last forever. It's an ST506 interface, so I should be able to use any of the solid state emulators that are out there to pretend it's a real spinning disk.

But right now goal 1 is getting my KDJ11-B swapped out for something that isn't throwing cache errors (if anyone's watching my videos on this, it's been a journey :), and then booting a basic RT11 image. Maybe I'll just do that through tu58fs. A pretty cool idea.
I used to repair 11/23 and 11/73 systems and use RT-11 a lot - sitting here currently copying files from the tu58fs at 19,200 (highest my GRC 2 x DL ports + 128KW runs at) to a partition on an SD card...

I've been running RT-11 and TSX on it - and various compilers, still looking for a complete CTS-300 distribution mind, I only have found ones with some files missing/mixed between versions, so it's a bit quirky, to say the least.

tu58fs is best tried on a real com port if possible, rather than a USB-RS232 at first until you know it's working reliably...

Drop me a message if you get stuck!
 
So I have both a pair of DLV11J's and a DHV11 in my /73 - my understanding is the DHV11 is probably the more kickier, and is probably best for this task. I'll be bringing the system back up tonight and i'll see about wiring up

(uhh, so apologies if this may be out of scope - i've been doing videos on getting this machine up and running, and at the risk of ya'll going "N00B! You don't know what the hell you're talkinga bout!!!" - feel free to check out what i've been working on. For the record, I'm doing the videos mostly because I"m having a stupid amount of fun with it - i'm not trying to be THAT YOUTUBE GUY. I'm just reliving my misspent youth :)

Also, just to be sure Im on the right project - we're talking https://github.com/j-hoppe/tu58fs for tu58s, right? The link to the 'docs' site is broken, does their download include a bootable RT11 image?
 
But right now goal 1 is getting my KDJ11-B swapped out for something that isn't throwing cache errors (if anyone's watching my videos on this, it's been a journey :), and then booting a basic RT11 image.

I left you a mesage on your latest Youtube post on this. It just so happens I have an 11/73 CPU board (KDJ11-B) sitting with the few spare boards I still have. Most are for pdp-8's. It's yours if you'd pay postage. It worked the last time I used it but that was years ago. I have one pdp-11/84 system and must have gotten this board maybe thinking it was another 84. I don't remember. But it just sits on the shelf looking for something to be. :)
 
I left you a mesage on your latest Youtube post on this. It just so happens I have an 11/73 CPU board (KDJ11-B) sitting with the few spare boards I still have. Most are for pdp-8's. It's yours if you'd pay postage. It worked the last time I used it but that was years ago. I have one pdp-11/84 system and must have gotten this board maybe thinking it was another 84. I don't remember. But it just sits on the shelf looking for something to be. :)
Well I'm not going to say no to THAT. Ummm, drop me a DM and we'll shake it out - i saw your comment, thank you! (I can't seem to send a DM here, maybe I'm just too shiny new).
 
So I have both a pair of DLV11J's and a DHV11 in my /73 - my understanding is the DHV11 is probably the more kickier, and is probably best for this task. I'll be bringing the system back up tonight and i'll see about wiring up

(uhh, so apologies if this may be out of scope - i've been doing videos on getting this machine up and running, and at the risk of ya'll going "N00B! You don't know what the hell you're talkinga bout!!!" - feel free to check out what i've been working on. For the record, I'm doing the videos mostly because I"m having a stupid amount of fun with it - i'm not trying to be THAT YOUTUBE GUY. I'm just reliving my misspent youth :)

Also, just to be sure Im on the right project - we're talking https://github.com/j-hoppe/tu58fs for tu58s, right? The link to the 'docs' site is broken, does their download include a bootable RT11 image?
Hi, The DHV11 can work with later versions of RT-11 - and are faster, but not for what you need at the moment, DL type lines are needed for the console and a DL line at address 176500, vector 300 is the default tu58 (DD) boot device, so you can just have the CPU, memory and the DLV11-J configured at 176500/510/520/530 in the system, and the RQDX controller to get it doing something... stick the other boards in anti-static bags!

There are bootable images and examples in the tu58fs docs, or I have some with batch files for Windows that are ready to go - just use 1 to indicate COM1 in the batch file, it doesn't make it clear in the docs...
 
I can put a 720k 3.5" floppy drive onto my 11/73. You can use PUTR on a PC to format and transfer disk images to it in a 400k RX50 like format. The RQDX3 doesn't know the difference and will boot from the disk as if it were an RX50 using the normal 11/73 boot firmware. RT11 and RSX/11M treat it as an RX50 drive.

That would give you a variant of the RX50 boot device and you are more likely to get 3.5" disks and drives. It is a bit of a shame as it only uses one side of the 720k disk.

Peter
 
I can put a 720k 3.5" floppy drive onto my 11/73. You can use PUTR on a PC to format and transfer disk images to it in a 400k RX50 like format. The RQDX3 doesn't know the difference and will boot from the disk as if it were an RX50 using the normal 11/73 boot firmware. RT11 and RSX/11M treat it as an RX50 drive.

That would give you a variant of the RX50 boot device and you are more likely to get 3.5" disks and drives. It is a bit of a shame as it only uses one side of the 720k disk.

Peter
That's a neat idea - but, here's a thought, how about modding the cable to select the other head as drive 1 - your double sided drive could emulate both drives in a real RX50, so you have 2 x 400KB... Not ideal - but still! - It actually closely resembles the RX50 with two heads on the same stepper and spindle... - just a bit more gap between them, lol
 
As RX50 is a MFM disk format you could also consider a floppy disk emulator such as a Gotek with Flash Floppy Firmware. I use them on other MFM systems. Though you would then need to be able to create / move files into the image.

Peter
 
Getting a Gotek with the flashfloppy will make your life a lot happier than fiddling with physical disks. I've gotten two of them running on my Pro/350 (in another thread) so you can perfectly emulate an RX50 pair for installs.

Also the TK50 is a fine tape unit, just need to lubricate the capstain bearings.

(If anyone's giving away MSV11-J memory boards let me know :)
 
That's a neat idea - but, here's a thought, how about modding the cable to select the other head as drive 1 - your double sided drive could emulate both drives in a real RX50, so you have 2 x 400KB... Not ideal - but still! - It actually closely resembles the RX50 with two heads on the same stepper and spindle... - just a bit more gap between them, lol
Not thought of that one! My 11/73 has working dual RX50s. I unplug the RX50s to plug in the 3.5" drive.

Peter
 
Getting a Gotek with the flashfloppy will make your life a lot happier than fiddling with physical disks. I've gotten two of them running on my Pro/350 (in another thread) so you can perfectly emulate an RX50 pair for installs.

Also the TK50 is a fine tape unit, just need to lubricate the capstain bearings.

(If anyone's giving away MSV11-J memory boards let me know :)
Now this is interesting (and hey CZ, how goes? :)

I have a Gotek floppy drive emulator setup. But what I think I'm missing is the proper cable. Is this your standard floppy cable with the pinned connector? The BA23 has the normal breakout panel between the card cage and where the drives go.

My RQDX3 is currently throwing ERROR 20 unfortunately whenever I try to do anything with DU0 - I suspect my RD52 is toast, but that's understandable. I'm not sure if this is really a problem with the controller or the drive. I'll rummage around the parts box and see what I can find.
 
The Gotek needs the Flashfloppy and for best emulation results needs to be configured as a Shugart and not an IBMPC device in the config. Then for one drive set it to drive 0 (I believe check my post on the Pro380 and Gotek) on a flat 34 pin ribbon cable. For two of them set one as drive 0, second as drive 1, both on a straight through 34 pin ribbon cable (no twist)

The RD52 could be anything from not formatted to stuck drive, to drive not being jumpered as drive 3. Try reading it with a Gesswin MFM emilator/data sucker.

And good to see you D! I've been doing this stuff for a long time... :)

CZ
 
So a bit of an update. I cabled in my GoTek (with FlashFloppy) into the breakout panel. It powers up, says "FLASHFLOPPY" and all that (i've used this before on other machines). The problem is the bootloader on the /11 is not showing an RX33 drive at all. Shows an RX50, RX01, and RX02, but no RX33 which is what I'd assume it would show up as. I did change the jumper to S0 to say IM A SHUGART, but no dice. I don't have an image / USB stick loaded yet - but i'm a little puzzled about how to get an RT11 RX33 image onto the USB - anyone have one lying around I could put on the Gotek to try and boot?

If I fail at this, i'll go the TU58 route next, but that requires cabling up another serial port to the DLV11J... doable, just tedious :)

1680367976335.png
 
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