David Betz wrote: Jerome Fine replies: I believe the ST225 is an RD31, but please do not rely on that!!!!!! Other advice has been provided on other e-mails. Use a BA23 or BA123. The cables are then a standard 50 pin and the standard PC 20 pin and 34 pin with edge connectors. Normally, the BA23 are BA123 have the distribution boards. Sincerely yours, Jerome Fine -- If you attempted to send a reply and the original e-mail address has been discontinued due a high volume of junk e-mail, then the semi-permanent e-mail address can be obtained by replacing the four characters preceding the 'at' with the four digits of the current year.

On Tue, 15 Mar 2005, Ethan Dicks wrote: DEC used Seagate ST225 (RD31) and ST251 (RD32) drives, various Seagate models for RD50 and RD51, three different vendors for the RD52 drive, two for the RD53 (Micropolis and ?) and then there's the RD54 (maxtor 2190) that comes in three flavors. So.. although the *format* must be DEC, this has nothing to do with the drive per se. You can format an ST251 as usual, and then "label" it as being an RD31. This will waste space, but other than that, it works fine. The RD32 _is_ an ST251. This is true.. most (but not all) full-height drives are faster than their same-capacity half-height friends, because of what Ethan just explained. The same goes for drives with more sectors per track, obviously. All this -does- depend on the drives, though, its not a given. Yes, you can make such a cable easily, especially if you're only going to connect a single drive. PeteD posted the howto on it. --f

On Wed, 16 Mar 2005 13:37:29 -0500, David Betz <dbetz at xlisper.mv.com> wrote: You're welcome. It's certainly the easier route as long as you can find a BA23 for cheap/free. I do not, but once upon a time, one of the cheapest sources was MicroVAX-Is... just pull out the CPU and set it aside. One bonus is that uVAX-I memory is Qbus memory and works great with PDP-11 CPUs (unlike uVAX-II memory, which is PMI). Another bonus is that if one _wants_ to play with Ultrix-32 v1 or MicroVMS, you still have all the parts. You can literally pull the CPU and/or memory from a MicroVAX I/II and drop in a KDF11 or KDJ11 and required memory, and *bam* - a MicroPDP... -ethan

Jerome Fine replies: While I agree that the RQDX3 is a great controller, unless the user has substantial hardware ability to connect a 50 pin cable to the hard drive(s) with 34 pin and 20 pin edge connectors, I suggest the use of a BA23 box which usually contains the panel for the distribution of the RX50 dual floppy drive and 2 MFM hard drives - although the front panel normally has buttons (READY / WRITE PROTECT) for just one hard drive. The BA123 box usually comes with the distribution board to handle the same RX50 floppy and 2 hard drives or up to 4 hard drives with no RX50 floppy - although you also require a SEPARATE assembly for the READY / WRITE PROTECT buttons for EACH hard drive. Being a person without hardware ability, I always choose the BA23 or BA123. These days, the hard drives might actually cost more than the SCSI host adapter (controller). The "nice" part about a SCSI host adapter is the capacity of the hard drives which can be 4 GBytes for very low cost - a few dollars. ESDI controllers are also now very inexpensive, but at least ESDI hard drives are also very large (600 MBytes were standard), but might also be hard to find. I also use all of the above - when I use a real PDP-11. 99% of the time, I now use an emulator under Windows 98 SE since I require 132 character text lines under KED on RT-11. Sincerely yours, Jerome Fine -- If you attempted to send a reply and the original e-mail address has been discontinued due a high volume of junk e-mail, then the semi-permanent e-mail address can be obtained by replacing the four characters preceding the 'at' with the four digits of the current year.