Moving from RQDX2 to RQDX3

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I have a running PDP-11/23+ in BA-23 enclosure. At present there is only the RX-50 floppy drive and two serial ports working. I have booted this system from an RT-11 floppy and from the second serial port to a PC running a TU-58 emulator.
It has an RQDX2 controller for the RX-50 and a hard drive. If I have an ST-225 hard drive it is my belief that a change to an RQDX3 controller will be necessary. Please comment?
If that is correct, what are the steps necessary to move from the RQDX2 to a RQDX3?
Thank you - Cliff Miller

[Johnny Billquist]

Post by ***@gmail.com
I have a running PDP-11/23+ in BA-23 enclosure. At present there is only the RX-50 floppy drive and two serial ports working. I have booted this system from an RT-11 floppy and from the second serial port to a PC running a TU-58 emulator.
It has an RQDX2 controller for the RX-50 and a hard drive. If I have an ST-225 hard drive it is my belief that a change to an RQDX3 controller will be necessary. Please comment?
If that is correct, what are the steps necessary to move from the RQDX2 to a RQDX3?

The RQDX2 have a different on disk format for hard drives than the
RQDX3. So if you change between the two controllers, a hard disk needs
to be reformatted.

However, since you are not using any hard disk right now, that is not a
problem. However, both the RQDX2 and RQDX3 are somewhat restricted in
which drives they accept. You cannot just take any drive and get it running.

However, I think the ST-225 was used by DEC, and called an RD-31 in
their systems, so it should be possible to use it on an RQDX3. (The
RQDX2 would not be able to use it, though, so your information is correct.)

What you need is the PDP-11 diagnostics which includes the program to
format the drive so it is usable on the RQDX3, and then you are good to go.
But it's a pretty small drive. Fine for RT-11, but probably a bit small
for any other OS.

Johnny