On 11/02/2012 02:15 PM, Earl Evans wrote: Avoid the ST251 they tended to fail often and way to often. The 225 is bullet proof. The RQDX3 can run up to 3 or 4 of them. NOTE: make sure the grant chain is not broken or the card can be the last on in the chain. Anything you bit required the MSCP boot for the RQDX3 and if the CPU is the 23+ then you have it as DUxx. Controller without drive should be at the Default address and the Boot DU driver should see it though it may return a no media or drive not ready error for no drive. The X11/XXDP diagnostics can test it if you have them. I've done this and what you propose will definitely work is the wiring is correct and the drive jumpers are set right (Should be set for ST225 as Rd31 The only difference I've done is my drives are RD52s (quantum D540 31mb full height MFM). If the chassis is a MicroPDP-11 (ba23) then the only thing you need is cables as the RQDXn to disk break out board is there. If its BA11 Then you can use the BA123 breakout board M9058 and that allows for up to 4 drives any mix of floppy or HD and the cables are simple 50, 34 and 26 pin with IDC headers. Note that board due to sockets is thick (3 slots) and requires ground, +5V but does not have to be in the backplane though it has the connector to do that (note it does not generate interrupts or any other bus signal) so it can be in the last open slot it fits in. I use that and RQDX3 to add floppies, hard disks or both to any Qbus system. The RX33 is Teac FD55GFR though RX23 (3.5" floppy) is also possible if the firmware is late rev. The M9058 is the standard distribution board used in all BA123 based system to go from RQDX 2 or 3 to floppies and hard disks. They can be found and cheap as most have no clue what they are or how to use it outside the BA123. It's a simple board that breaks to 50pin out to the drives and also allows for drive enable and write protect lights and switches. Those light and switches are not required but easily made and fun to have. the select logic allows up to 4 hard drive drives or the the mix can be one floppy and 3-4 HD. The floppy is nominally RX50 or RX33. NOTE: if you use the M9058 then it can be put int he box with Floppies and hard disk where it gets power and connected to the main system via RQDX2 or 3 using a simple 50pin to 50 pin IDC headered cable up to 4ft long (never tried longer but may work). I have 4 systems PDP11-23+ set up this way 3 in BA11 and one BA23 (microPDP11) and a few uVAX in BA23 and BA123 . The large system (J11 based ) has RX02, RL02, RD52*2, RX33 and makes file transfer and all much easier. I nominally run RT11XM on it. Allison

Booting from RT-11 and TSX-Plus is easy if you have a distribution of the files on the RD32. If you also have an RX50 floppy drive, you can copy the files to the RX50 media and then transfer to the RD52. Ask if you don't know how. What is the version number of the EPROMs? Some of the most recent versions have the code to boot MSCP drives directly. Otherwise, if you have other types of drives such as an RL02 or TU58, you can boot these first. As a last resort, you can enter the boot code by hand for RD52 (MSCP) drives. An RX50 will usually work. Perhaps test with that first. Any other questions? Please let us know how successful you are. As usual, I am curious what you will use the PDP-11/23+ for? Surely it will be for more than to just hear the fans running. Do you have any specific software to run? Jerome Fine