M7846 and assorted questions

[Qbus]

Before I pony up and pay $70 for a M7846 RX-01 controller card on EBay thought I would ask one last time if anyone here had one? Also what’s the deal with reading disks written on a RX-01 on a RX-02? All the books say it can be done but have not gotten to that point yet, am assuming that if I format and build a system disk on the 01 drive that it would work on the 02 drive but back when I had my RX-02 working did not appear to get a lot of love from the disks that I thought were written on a 01 drive, matter of fact think it was the working with both formats that killed the RX-02 that I have but that may just be coincidental. Just to review now I have a working 01 drive with a Qbus controller and hope to have a Unibus controller soon. Have a RL-02 system disk on the way and when it gets here want to use the 11/34 to build a system disk on the RX-01 drive then connect the RX-01 to the 11/23 and rebuild the RL-01 system disk. The TU-58 project is going forward but that will have to work with the 11/23 and another stupid question, will a RL-02 drive read a RL-01 disk pack?

 

[Lou - N2MIY]

Ray,

$70 sounds a bit high, but not astronomical. I myself only have one, or else I'd send you one.

An RX02 works perfectly fine in RX01 mode on an RX11. I have done it. The key is setting the two switches correctly in the RX02. You need to set the RX02 to work like an RX01.

If some day either of us are lucky enough to get an RX21, then we can use the RX02 to its full potential. Then, it can boot and read RX02 media, but it will only be able to read RX01 (and not boot) unless we open it back up and throw the switches. I am at the point where I have not bothered to put the screws back to secure the top hinged board and have a little sticker by the switches to remind me what combination is for what mode.

In my opinion, we are not loosing much only having RX01. Most stuff I have come across is on RX01. I can still read and work with RX02 disks, but it is on one of my q-bus systems, which have RXV21 controllers.

I am very sure that RX01 disks did nothing to harm your RX02 drive.

As for RL02 drives reading RL01 media, it is possible, but requires hardware modifications. I have never tried, since I have one fine working RL01 drive in addition to the mess of RL02 drives I have. I too am on the lookout for RL01 media since I have only one good pack (but honestly I never use the RL01 drive anyway.)

Lou

 

[Qbus]

Went ahead and bought the big money RX-01 controller card. Also have my new RL-01 RT-11 system disk. The current plan is to finish repair of a third RL-01 drive that I have and set the 11/34 up as a dual RL-01 disk system and keep the 11/23 as a signal drive RL-01 system. Fortunately I have a bunch of RL-01 drives so this should not be an issue, thought the new system disk would be a RL-02 but it turned out to be a 01 and that’s good being that the 11/23 system only has the 01 control cards. Have a couple RL-02 drives and perhaps at some point will do something with them. Would like to do something with them being that they are good looking drives that are lighter, have modern style power cords and are relatively new being manufactured in 1984. May have to put together a third system using them? Still have an 11/34A out in the garage! The next big project after finishing the work on the second drive for the dual drive system will be trying to build up a second and third RL-01 system disk packs; somehow it’s a little more than just copy DL0 to DL1.

 

[Lou - N2MIY]

Ray,

It's not much more. Once the target pack is initialized and in drive 1, with the master pack in drive 0 all there is to do is:

COPY /SYS DL0:*.* DL1:*.*
COPY /BOOT DL1:RT11FB.SYS DL1:

and you are done.

Also, all RL11 controllers can control both RL01 and RL02. They are not drive specific. Not RL11, RLV11, or RLV12. You can even mix drives on one controller. I've done all that.

This is not true on a PDP-8 / RL8A however. It does not support mixing.

Lou

 

[Qbus]

You the man! With your instructions I was able to build up a couple RL-01 system disks with RT-11 on them. My dual drive 11/34 is working great after I repaired the motor control card on the #1 drive. Used Initialize to wipe a couple RL-01 packs I had and installed new RT-11 systems on both. Still have issues with the 11/23 with the RX-02 being evil and also started getting flakey results with the RL drive on that system, think that one is jealous of me spending more time on the unibus system. Got the holiday and couple days off work so looking forward to getting all the issues resolved with the drives on that system, but have some degree of satisfaction now having a complete working dual drive 11/34

 

[Lou - N2MIY]

It is weird how the systems that are next to each other do seem to exhibit "jealousy". My 8/e and 11/04 are in racks side by side. If I am playing with one for a while, surely the next time I fire up the other one, something is broken. So then I spend hours on the other one getting it running again. It's probably just they're both old and have a low MTBF, but it sure seems funny.

Anyway, congrats on recent progress.

Lou

 

[Qbus]

The two systems are side by side. Was thinking of pulling the 11/23 and installing it in a second DEC mast head rack that I picked up that matches the one the 34 is in. Have couple six foot DEC racks and may end up using one of them for the 11/34 system with the RX-01 drive although now that I have a dual RL drive system don’t know if I will need a floppy on the 11/34 system, and space in the shop is getting to be a little limited.