Writing RX02 floppy.

[MattisLind]

I had the idea that I'd like to boot RT11 on an machine with a RX02 drive. But what is the way to write arbitrary image to a RX02 diskette?
I can create bootable disks on SimH but how to transfer the disk image onto a floppy?

The RX02 is special so it cannot be written or read by a standard PC floppy controller. I have a catweasel card which at least read a RX02 diskette without (not that much) problem. But how to convert back and forth the raw disk image from the DMK format? I have tried an old lib developed by Eric Smith called dmklib but seems not to support RX02. Hints are welcome here!

Or is the only way to boot RT11 from some hard disk and then create bootable disks? I really like to do the fiddling in SimH and then just transfer the image onto the media, but that might not be possible?

I did have some problems reading a number of RX02 formatted disks. From track 44 an onwards it started to fail on reading. Does this has to do with the media, the drive that was used for writing or the drive used for reading? The drive read other disks past track 44 without any problems. I am using a Shugart 851 which seems to have some jumpers that would be able to control the reading filters some how. Haven't tested yet though.

 

[iainmaoileoin]

assistance?

assistance?

I had the idea that I'd like to boot RT11 on an machine with a RX02 drive. But what is the way to write arbitrary image to a RX02 diskette?
I can create bootable disks on SimH but how to transfer the disk image onto a floppy?

I am running "real" RX02 disks.

I use BSD2.11 for a lot of the plootering about with images. I find it quick and easy to take (e.g.) a simh file,
ftp it over to BSD and the just use the BSD "dd" command to image write to the disk. If you dont know, BSD will move an image for a lot of foreign system - so RT-11, RSX, dec-diags. It does not care what type of system is in the image, it does not have to be Unix.

I have used BSD to get dec-diags onto RL02, RT11 onto RD disks, RT-11 images onto RK05 media etc.

Even if the target system is not going to run BSD, BSD is a great tool for data manipulation.

If you want to email me your image file I can dd it up to some RX02 media and snail-mail it back to you? It might remove some variables from your equation? What controller do you use?

 

[glitch]

I'm using 2.11BSD for image manipulation needs as well. If you don't want to get an entire 2.11BSD environment set up, you can use vtserver to send RX02 images over the console and write them out to physical RX02 disks. You'll need at least a PDP-11/23 though, and IIRC 192K of RAM.

 

[PG31]

IF you have a second serial port why don't you try one of the TU58 emulators? I booted one of my micro PDP-11's with the XXDP image via TU58em and created bootable images on an RDxx and an TK50 drive.

 

[Lou - N2MIY]

I'm using 2.11BSD for image manipulation needs as well. If you don't want to get an entire 2.11BSD environment set up, you can use vtserver to send RX02 images over the console and write them out to physical RX02 disks. You'll need at least a PDP-11/23 though, and IIRC 192K of RAM.

Would that work for writing OS/8 RX02 floppies? Also, could that setup be used to make images of OS/8 RX02s?

Lou

 

[MattisLind]

OK. The consensus seems to be that the best way is to install a 2.11 BSD system and then use that for moving images back and forth. I have a KDF11 + 256 kbyte memory + SCSI board which boots RSTS/E and RSX11-M. I thought that 2.11 BSD was not supported on the F-11 since it is lacking split I+D. Does anyone have a MSCP bootable image for an 11/23 to share that I can move to my SD-card (to insert into the SCSI2SD adapter)?

Anyway. I still thought it would be interesting to use the Catweasel card and it successfully read a couple of RX02 images. I tried dmklib by Eric Smith but it didn't work so I researched the source code and there are a number of small things that prevented it to understand the RX02 format of the DMK-file. Some small patches to the program made it to work. It was able to produce an image that then could be mounted by SimH and do DIR from within RT11.

I will continue to work on the dmklib to have a prettier fix so it will be able to convert between raw disk images and RX02 DMK.

 

[glitch]

Would that work for writing OS/8 RX02 floppies? Also, could that setup be used to make images of OS/8 RX02s?

Lou

Not sure, I don't know anything about OS/8 disk formats. If the controller is writing out the same track/sector formats, just using a different word length within the sector, it might work. I'd be happy to try one for you.

 

[antiquekid3]

Not sure, I don't know anything about OS/8 disk formats. If the controller is writing out the same track/sector formats, just using a different word length within the sector, it might work. I'd be happy to try one for you.

RK8E uses 16 sectors; RK11 uses 12 sectors. I'm thinking it'd probably not work.

 

[AK6DN]

RK8E uses 16 sectors; RK11 uses 12 sectors. I'm thinking it'd probably not work.

RK8E (for the RK05 platter) on a PDP-8 is a totally different beast vs the RK11 for the PDP-11.
The media cartridges are physically different (as indicated) and are not compatible.

RX01/02 on the PDP-8/11 are different however. There is no physical difference in the device sectoring.
The only difference is that on the PDP-11 8 bit bytes are written out per sector (128 or 256 depending on RX01 or RX02 mode),
whereas on the PDP-8 12 bit words are split into 4b nibbles and two twelve bit words are packed per three 8b bytes.
PDP-8 RX01 has 64w per sector packed into 64*12b / 8b = 96 bytes used out of 128.
PDP-8 RX02 has 128w per sector packed into 128 * 12b / 8b = 192 bytes used out of 256.

So a PDP-11 can read/write PDP-8 disks without doing anything special if it just reads/writes the full sectors (which is normal for the PDP-11).

Refer to http://homepage.cs.uiowa.edu/~jones/pdp8/man/rx01.html for lots more details.

 

[iainmaoileoin]

Sorry

Sorry

... thought that 2.11 BSD was not supported on the F-11 since it is lacking split I+D. Does anyone have a MSCP bootable image for an 11/23 to share that I can move to my SD-card (to insert into the SCSI2SD adapter)?

Dumbo here did not read your system type -sorry, yep sep I+D is needed. Sorry ;-(

 

[antiquekid3]

Just realized Lou was asking about RX, not RK. Oops. I blame it on my lack of sleep from studying for exams.

 

[glitch]

Dumbo here did not read your system type -sorry, yep sep I+D is needed. Sorry ;-(

That just means no 2.11BSD -- there are other versions that will work without split I+D. You may find they lack TCP/IP, I don't remember. In any case, you could transfer images via serial line (e.g. Kermit, XMODEM) if you had any sort of UNIX up and going.