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Want to add RX50 to my PDP-11/23

smp

smp

Veteran Member
Joined
Oct 4, 2011
Messages
1,727
Location
Bedford, NH, USA
Good morning all,

I have posted before about my adventures with my PDP-11/23:

BA11-N Chassis
H9273 Backplane
M8186 Processor
M8059-KP 256K Memory
M7940 Serial I/O (strapped as the console I/O port)
M7940 Serial I/O (strapped as I/O port 0 for TU-58 tape emulator)
Emulex UC07 SCSI Interface
empty row
empty row
empty row
M8012 Diagnostic / Boot

I am currently running RT-11 by entering a small amount of boot code via ODT and executing the bootstrap available from the Emulex UC07.

I am considering possibly adding an RX50 floppy disk to my system.

Please confirm that I will need an M7555 controller and a RX50 floppy disk drive.

What power supply will I need? Also, is the interface cable a straight-through flat cable?

Am I missing anything?

Thanks in advance, for your patience and advice.

smp
 
Hi SMP,

You are right with the 7555 controller. The output from that card is a flat ribbon that goes to a "distribution board", for want of a better name. Cables come out of that board to the hard disk (MFM) or RX50 floppy drive.


Cheers,

Andy.
 
acollins22 said:
You are right with the 7555 controller. The output from that card is a flat ribbon that goes to a "distribution board", for want of a better name. Cables come out of that board to the hard disk (MFM) or RX50 floppy drive.
Click to expand...

Hi Andy,

Thanks a million for your response. I'm glad that I'm getting to the point that I actually can get myself somewhat on the right track with my DEC equipment, before I go off and start asking questions.

smp
 
DDS said:
You might want to start with a look here:

http://www.avitech.com.au/pdp-11-03/rqdx-wiring.html
Click to expand...

Hi DDS,

Thanks *very* much for this. Looks like that is the (or one of the) distribution board that Andy was talking about.

Is it possible to start off by directly wiring from the M7555 to the RX50, and maybe later acquiring one of those boards?

I did not study the web site you pointed out very deeply - are these boards available for sale, or am I stuck waiting for the right thing to come available on eBay?

Hey, now I see that the breakout board you pointed me to is much better than I originally thought. It would allow me to use 3.5 inch drives!

Thanks!

smp
 
smp said:
Hi DDS,

Thanks *very* much for this. Looks like that is the (or one of the) distribution board that Andy was talking about.

Is it possible to start off by directly wiring from the M7555 to the RX50, and maybe later acquiring one of those boards?

I did not study the web site you pointed out very deeply - are these boards available for sale, or am I stuck waiting for the right thing to come available on eBay?

Hey, now I see that the breakout board you pointed me to is much better than I originally thought. It would allow me to use 3.5 inch drives!

Thanks!

smp
Click to expand...

I'm not far enough along yet to have investigated that break out board more than just being aware of it and reading the info on the web site. For some reason I seem to recall the guy has posted here in the past. I for one would like to acquire one somewhere down the road if he makes them available for sale.
 
That's a terrific page. Even if you don't want the breakout board there's a lot of information to help get started.

Thanks for posting that.


Andy.
 
I assembled and ran one of Malcolm's breakout boards. They are much more versatile and easier to configure than an M9058.

For fun, I had David's MFM disk emulator and a Gotek floppy emulator connected to Malcolm's breakout board, connected to an RQDX3. It all played together quite nicely. There's an all solid-state storage solution for your pdp-11!

Lou
 
Lou - N2MIY said:
I assembled and ran one of Malcolm's breakout boards. They are much more versatile and easier to configure than an M9058.
Lou
Click to expand...

Did you acquire a bare PCB board from someone or did you have one made yourself? That looks like a handy board to have.
 
I was lucky enough to be a tester for Malcolm when he made his first run of boards. He does check in here on the vintage computer forums occasionally. You can send him an e-mail and ask about availability of the PCB. You can also wire-wrap your own.

I had to go to the wayback machine to find the contents of the page, but there is also good stuff on a home made RQDX signal distribution board here: http://www.dunnington.u-net.com/public/RQDX/ . I wire wrapped my own from the drawings in that directory.

Lou
 
Lou - N2MIY said:
I had to go to the wayback machine to find the contents of the page, but there is also good stuff on a home made RQDX signal distribution board here: http://www.dunnington.u-net.com/public/RQDX/ . I wire wrapped my own from the drawings in that directory.
Click to expand...

I'm having trouble getting that link to open up.. Keep getting a "failed to open page" message. Is there any mirror of this site available?

smp
 
DDS said:
I for one would like to acquire one somewhere down the road if he makes them available for sale.
Click to expand...

I have a few still available. I'm not sure exactly how many, as I'm away from home (Melbourne, Australia). I'm currently in Chicago as I came over for VCF MW this past weekend. I'm happy to sell them for US$20/ea plus postage from Australia. If anyone wants one, please let me know and I'll advise total price (including postage) next week. Otherwise feel free to wire wrap one based on this design. If you omit the wiring for the MFM hard drive, the wiring for just the floppy drives is not too complex.
 
Mal said:
I have a few still available. I'm not sure exactly how many, as I'm away from home (Melbourne, Australia). I'm currently in Chicago as I came over for VCF MW this past weekend. I'm happy to sell them for US$20/ea plus postage from Australia. If anyone wants one, please let me know and I'll advise total price (including postage) next week. Otherwise feel free to wire wrap one based on this design. If you omit the wiring for the MFM hard drive, the wiring for just the floppy drives is not too complex.
Click to expand...

Mal, I sent you a PM, but I did not receive a reply. Perhaps like me sometimes, you did not get notified of the message.

For the record, I am interested in purchasing one of your boards for US $20 plus shipping from you in Australia, to me in Bedford, NH USA.

Please see the PM I sent for my full name and address.

smp
 
Lou - N2MIY said:
I assembled and ran one of Malcolm's breakout boards. They are much more versatile and easier to configure than an M9058.

For fun, I had David's MFM disk emulator and a Gotek floppy emulator connected to Malcolm's breakout board, connected to an RQDX3. It all played together quite nicely. There's an all solid-state storage solution for your pdp-11!

Lou
Click to expand...

Hi Lou,

I am also interested in utilizing something like the Gotek floppy disk emulator. On eBay, there are a variety for sale, at a variety of prices. Which did you purchase? I am thinking to purchase one of the inexpensive ones (~$20) that simply say they emulate a 1.44 MB 3.5 inch drive, and mention that it is for a Roland something-or-other.

What say you?

smp
 
Last edited:
I bought one of the ~$25 units also. The seller I got mine from shipped from Brooklyn. I had a quick look and didn't recognize the sellers I saw now, but it was at least a year ago that I bought them. Once I was satisfied with the first one, I did buy a second one. Mine has a three digit display (can store 1000 images on the USB memory stick.) Crawford bought one also an his worked perfectly also. There is a thread here somewhere where he and I discussed our findings when we examined the contents of the memory stick. It's not FAT formatted. Instead it is simply raw head/track/cylinder/floppy data, all one right after another.

I use this on my bench testing qbus machine. I have it on an RQDX3, and then have bootable floppy images set up with various useful XXDP routines.

Lou
 
smp said:
Mal, I sent you a PM, but I did not receive a reply. Perhaps like me sometimes, you did not get notified of the message.
Click to expand...

Apologies for the delay - I have just responded to your PM.
 
Lou - N2MIY said:
I bought one of the ~$25 units also. The seller I got mine from shipped from Brooklyn. I had a quick look and didn't recognize the sellers I saw now, but it was at least a year ago that I bought them. Once I was satisfied with the first one, I did buy a second one. Mine has a three digit display (can store 1000 images on the USB memory stick.) Crawford bought one also an his worked perfectly also. There is a thread here somewhere where he and I discussed our findings when we examined the contents of the memory stick. It's not FAT formatted. Instead it is simply raw head/track/cylinder/floppy data, all one right after another.

I use this on my bench testing qbus machine. I have it on an RQDX3, and then have bootable floppy images set up with various useful XXDP routines.

Lou
Click to expand...

Hi Lou,

Thank very much for that information. I have been thinking pretty much the same thing, with the RQDX3 and bootable floppy disk images. I'm happy to hear that I am on a reasonable track, where others have already had success.

smp
 
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