MSCP SCSI controller speed

[Tim Shoppa]

>From a post I made to the PDP-11 newsgroups in the previous
millenium:

The benchmarks were done under RT11FB 5.7 doing 1, 2, 4, 8, 16,
32, and 64 block-at-a-time READW's and WRITW's to 16384-block
data files.  A KDJ11B (PDP-11/73) CPU with 2 Megabytes of Clearpoint
non-PMI memory was used for the bencharmks.  With the SCSI
controllers a Barracuda 7200 RPM ST15230N drive was used; with
the RQDX3 a RD52 drive was used.


Here are the peak data rates measured for read and write 64
blocks-at-a-time:


                   Read           Write
                  ----------     ----------
Andromeda SCDC    2.298 MB/s     1.131 MB/s
CMD CQD440        2.397 MB/s     1.525 MB/s
CMD CQD220        1.418 MB/s     0.882 MB/s
CMD CQD220A       2.088 MB/s     1.409 MB/s
DEC RQZX1         1.379 MB/s     1.097 MB/s
Viking QDT        0.846 MB/s     0.704 MB/s
DEC RQDX3         0.164 MB/s     0.161 MB/s