DEC RD54 from Maxtor - problem with DK515-78?

Jerome Fine replies: I have used both the Hitachi DK515-78 and the DK516-15 drives with an RQD11-EC ESDI controller from Sigma. I must be missing something. The larger DK516-15 drive (1.2 GBytes) is very slow - about a third of the speed of the DK515-78. I suspect that I need to interleave the sectors, but I have not been able to find a setting to do that with the RQD11-EC. In addition, I am normally able to compare one RT-11 partition on one DK515-78 drive against a different but identical RT-11 partition on a second DK515-78 drive in about 4 minutes and 11 seconds. For those who don't know, an RT-11 partition is 32 MBytes. I use BINCOM in that case and the CPU is a PDP-11/83 in a BA123 box. However, when I have more than 7 quad boards in the backplane, the compare time increases to about 10 minutes. I suspect that the problem is that my system is on the very edge of some hardware condition which causes everything to slow down, the same problem perhaps as with the DK-516-15 drives. Can anyone suggest what could be causing the difficulties? The system is about the same when I use a PDP-11/73 and normal memory except that I don't seem to remember having a problem when there were more than 7 quad boards and I used the DK-515-78 drives. But the DK516-15 drives are always very slow. 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.