RK05 disk drive versions

[Roland Huisman]

Last Friday I've picked up these lovely little RK05 drives... There are some differences between them.
There are two RK05 drives and two RK05J drives.

One of the RK05 -seems- to be converted to a RK05J. The M7702 is replaced by a M7681 and the
M7700 is replaced by a M7680 to convert from a RK05 to RK05J. I was wondering, is the backplane kept the same?
And is there a document which describes the other differences in detail?



I knew these drives were coming to me and I wanted to have a simple test interface.
DEC had the RK05 exerciser but these are probably impossible to find. So I've drawn a PCB to
interface with the disk. The test routines are described in the RK05 exerciser documentation.
The idea is to put an Arduino Due on the board and plug it into the drive. Or use an Unibus cable and
two H851 blocks. Then you could use the board outside the drive. Maybe it is even possible
to read or write disk images at a later moment. We will see how things will go...



But it would help to know the differences between the drive versions. And I wonder if it would
have any influence on the test routines...

Regards, Roland

 

[vrs42]

I knew these drives were coming to me and I wanted to have a simple test interface.
DEC had the RK05 exerciser but these are probably impossible to find.

I drew the exerciser once upon a time. Even ordered all the parts, chicken-head knobs and all (except the PCB itself).

I can't help with version specific info, except to recommend browsing the ECO logs. I doubt there was much different about the interface, though, as AFAIK they all talk to the same controller.

Vince

 

[Ed Groenenberg]

I agree. As far as I know (and could find in the manuals ans such) the difference is merely the improved cards (M7680 and M7681).

And regarding the exerciser, I have only seen the (same) picture, never seen one in real life.

Oh, and an USB to RK05 interface, I'll take 2 please!

 

[bqt]

I agree. As far as I know (and could find in the manuals ans such) the difference is merely the improved cards (M7680 and M7681).

And regarding the exerciser, I have only seen the (same) picture, never seen one in real life.

Oh, and an USB to RK05 interface, I'll take 2 please!

Interestingly, the RK05j "sticker" I have on one of my drives is the one on which a unit select switch was added to the front. On these pictures, one drive have that modification, but that one does not have the updated front sticker.

But apart from that, and some other internal improvements, I don't think there is any relevant differences between the drives. I wonder if the ability to run 8 drives on a controller requires the updated cards, possible. Old style addressing have four pins. One for each drive. So a max of 4 drives on the controller. There are variants of controllers which select drives with a binary encoding on these pins instead, and allowed for 8 drives.

As for the RK05 exerciser, I happen to have one. Never used it, though.

 

[gnupublic]

As for the RK05 exerciser, I happen to have one. Never used it, though.

Are you interested in selling the exerciser? I will have to bring eight RK05 back to play and would be interested in this tool. I think Roland is also interested, maybe we could share the tool?
greetings,
Volker

 

[bqt]

Are you interested in selling the exerciser? I will have to bring eight RK05 back to play and would be interested in this tool. I think Roland is also interested, maybe we could share the tool?
greetings,
Volker

No plans to sell it. In addition, I have it somewhere in Sweden, while I live in Switzerland. And with the current travel restrictions, I doubt I'll get near it for the next six months...

 

[Ed Groenenberg]

CCould you make a few picture of it when you are back in Sweden?
I only know the picture form the manual.

 

[bqt]

CCould you make a few picture of it when you are back in Sweden?
I only know the picture form the manual.

That I could. But you'll have to remind me in July, when I might be getting close. I have a lousy memory.

 

[MattisLind]

I also have a RK05 exerciser. Will probably get to it sometime before christmas. Will be able to take pictures.

/Mattis

 

[Roland Huisman]

Hi Volker,

I will have to bring eight RK05 back to play and would be interested in this tool. I think Roland is also interested, maybe we could share the tool?

Well I think you are not the only one with a bunch of these drives which need to be restored.
That is why I want to make something easy to built for others. Another part of my plan
is to make the RK05 boards available for testing in Vince/Warrens Flip Chip tester



I need more hours in a day :sigh:

Regards, Roland

 

[m_thompson]

Another part of my plan is to make the RK05 boards available for testing in Vince/Warrens Flip Chip tester

Testing the completely digital boards like the M7680 and M7681 should be easy. The other boards that are partially analog and partially digital will take some extra effort.

I wrote Windows software to control Warren's tester using a SPI-USB dongle. I need to write my own SPI library because the library from FTDI is incredibly slow.

 

[Roland Huisman]

I have built my RK05 test interface and currently writing software for it.
Until so far it is doing what I want...



While being busy with the software I was wondering where I can find
information about how the RK05 disk images are built up. Would be nice
to have a reference. Does anyone have a good tool to analyse these images?

Regards, Roland

 

[bqt]

I have built my RK05 test interface and currently writing software for it.
Until so far it is doing what I want...

View attachment 65063

While being busy with the software I was wondering where I can find
information about how the RK05 disk images are built up. Would be nice
to have a reference. Does anyone have a good tool to analyse these images?

Regards, Roland

What images? Maybe I'm missing something here, but I don't know what we might be talking about here? Are you looking for information how an actual RK05 track looks like? Does anyone have a dump of a disk at that level? Or if we're just talking about a dump of the data, then are you looking for understanding the file system? In which case we need to know which operating system we're talking about.

 

[vrs42]

I have built my RK05 test interface and currently writing software for it.
Until so far it is doing what I want...

The photo makes me want one .

While being busy with the software I was wondering where I can find
information about how the RK05 disk images are built up. Would be nice
to have a reference. Does anyone have a good tool to analyse these images?

The SIMH image for an RK05 has the 12 bit words as the LSB of 16 bit words, stored as two bytes each. The unused bits are set to zero. The 256 word blocks are thus represented in 512 bytes, and successive 512 byte blocks are just stored in the file one after another starting with block 0. If you are trying to build OS/8 file systems, I've got tools for that.

Details about interleave and stuff are usually hidden by the device drivers, so you may need to peruse the RK05 system handler for that. If there's a software interleave in the driver, I'm not aware of it, though, so I suspect that unless you're doing formatting stuff, that is actually hidden, even from the driver.

I seem to remember some kludge that allows one to transfer 128 words, and abort the transfer at mid-block, but I don't think OS/8 uses it. MAINDECs probably do, though.

Doug has probably looked at the details of the RK05 handlers more than I have.

Vince

 

[Roland Huisman]

What images?

Well there are a lot of RK05 disk images made from real disks. These images can be used in simh of written back on a disk.

Are you looking for information how an actual RK05 track looks like? Does anyone have a dump of a disk at that level? Or if we're just talking about a dump of the data, then are you looking for understanding the file system? In which case we need to know which operating system we're talking about.

Well, the primary goal of my board is to just have the RK05 exerciser functionality.
But since I have a USB connection to the PC it might be possible to read an entire disk to an image file.
Or if you have an image file you could write it back to a disk. To do this I need to know how
the data on the disk is stored vs how it is saved in an image file.

The photo makes me want one

No problem :D But I want to have it up and running first off course...

And thanks for the information about the disk image. Besides reading or writing a disk image I already got
the question if a real RK05 could be used under simh. To be honest, I was expecting this question...
That is why I used the Arduino Due with an native USB port and USB serial port. And for its speed off course.

The future idea is that the USB serial programming port, can be used with tera term to use the Exerciser
and read or write an image without simh... The native port could be used to represent a disk in simh.
But I don't want to end up with implementing file systems...

So my questions might be two steps ahead from where I'm now with my development.
But I like to have some inputs / ideas which might be helpful. I'm also wondering what
is done with the spare tracks from the RK05 disks within an image...

And I'm very interested in the OS/8 tools you have for the disk images.
Any tools for the PDP11 as well?

Regards, Roland

 

[djg]

I'm also wondering what
is done with the spare tracks from the RK05 disks within an image...

And I'm very interested in the OS/8 tools you have for the disk images.
Any tools for the PDP11 as well?

Regards, Roland

I'm pretty sure the PDP-8 or at least OS/8 didn't have any bad block handling for RK05 so you needed to use error free packs. It did have bad block handling for the RL drives.

The software archive stuff on my site uses WinEight flx8 under the hood for accessing disk images. My web stuff probably makes code harder to use. If you can't get flx8 from Spare Time Gizmos site I can send you the copy I have.

 

[vrs42]

And I'm very interested in the OS/8 tools you have for the disk images.
Any tools for the PDP11 as well?

The tools are maintained at http://svn.so-much-stuff.com/svn/trunk/pdp8/8tools/.
There is a doc/ subdirectory with the markdown write-ups for the tools. The best way to get them is with your local equivalent of the command "svn co http://svn.so-much-stuff.com/svn/trunk/pdp8/8tools/". That will create a checkout of the entire tools directory, and you can then so "svn update" in that directory (or subdirectories) to update to the latest version.

I use them under WSL, but they work fine with Linux and used to work fine with Cygwin, though I haven't tried that in a while. The cross assembler is in C; everything else is Perl, so you'll need to be sure you've got a Perl installed somewhere. You can even run stuff directly from Windows if you've got that (though line endings continue to be a pain).

Anyway, os8xplode and os8implode work directly with "dsk" format images, which also happen to be the same format as SIMH uses for RK05. The xplode script will create .0 and .1 directories for the two file-systems, and sufficient XML and .boot, .kmon, etc. files that implode can re-create the disk image.

I used them extensively with SIMH to debug my VC8E demos at http://svn.so-much-stuff.com/svn/trunk/pdp8/src/vc8e/, and also for forensic work with old images.

Other stuff there deals with images that aren't OS/8, paper tape stuff, conversion to and from dsk format for DECtape/floppy, etc. bin2pal is the disassembler, bincmp also gets a lot of use.

The bin2c converter (and it's predecessor, bin2perl) are mostly a lark, to prove it could be done.
The pqs8 stuff works, but doesn't really feel "finished" yet. (You probably don't have many pqs8 images anyway.)

I do keep finding and fixing issues, including a corner case in bincmp earlier this week involving files which have the location bit set on their checksum. Oh, and the cross assembler doesn't get this right:
*.-1 177+1
(It incorrectly treats it as "*.-1;177+1", whereas what it should do is similar to "page".)

Alas, no help yet for PDP-11 stuff, though I'd think it was quite doable.

Vince

 

[DougIngraham]

The RK05 handler for OS/8 does not do any kind of interleave or handle bad blocks. The RX01 handler is the only one I can think of that does interleave in the handler.

Best wishes!

 

[Roland Huisman]

So I've spent a few hours on the drives. These were once spare part drives and there were no intentions to use them ever again.

All the foam was in bad shape off course. So I made new sealing foam for all the drives.



In one drive the fan has eaten the foam and put it all in the air filter...


All washable parts were cleaned thoroughly, but I got some new parts too.


One air filter was really dirty with a black greasy dirt. That filter is replaced.


I've replaced the bearings in all except one fan. These were too noisy...


One of the rubber dampers fell apart. So I had to search for a replacement.
Finding the right size was one thing, but the right hardness was another problem.
I think my new damper is a bit too hard, but I cant find any other model...


I've been given another front panel to replace this one.


And I still wonder why this extra switch is in the first RK05 drive which I had earlier.
That drive seems to be a very old one, there are more differences with later drives...

 

[SteveG]

Alignment disk

Alignment disk

From what you say these may be helpful at some stage (unless you already have them).



Head alignment disk and test programs.