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RZ Disk Drive Spin-up Control

VAXstation 3100 Firmware

                                                10 June 1997.  SMS.

      Configuring RZ Disk Drives using VAXstation 3100 Firmware.

   As supplied, DEC RZ-series disk drives do not spin up when power is
applied.  They wait for a SCSI start unit command.  This allows the
system to start multiple disks sequentially, to reduce the transient
load on the system power supply.

   Some other systems (Macintosh, for example) do not issue the
necessary command, so these disks always appear unready to such systems. 
The firmware on a VAXstation 3100 can change this setting of these disk

   On a VAXstation 3100, plug a special hardware key into the
Communications Port MMJ (denoted by the arrows).  The key is a DEC H3103
loopback plug, which connects pin 1 to pin 6, pin 2 to pin 5, and pin 3
to pin 4:

      |  +--------+  |
      |  |  +--+  |  |
      |  |  |  |  |  |
      1  2  3  4  5  6

   At the console (">>>") prompt, enter "TEST 73".  Answer the questions
about the SCSI port (if you have the SCSI/SCSI controller) and the SCSI
ID of the target disk drive.  When asked "...rusure (1/0) ?", answer
"42000001" to enable prompt spin-up, or "41000001" to disable prompt
spin-up.  Interesting messages appear, and the change should be made.

   RZ23 and RZ24 disks respond correctly even when not ready (spun-up),
but an RZ56 does not.  (The "TEST 73" command loops, waiting for the
RZ56 to become ready.)  The console mode command "SHOW DEVICES" should
start an RZ56, and after it becomes ready, the "TEST 73" command should

   The normal use for the "TEST 73" command is to make a special TK50
tape (using a TK50Z or TZ30 tape drive).  The particular data written on
this special tape are recognized by the firmware for the tape drive
diagnostic, allowing it to do write testing on this tape.  The tape
drive diagnostic normally avoids write testing, to avoid accidental data
loss.  If you answer "0" or "1" to the "...rusure (1/0) ?" question,
the program will attempt to make this special tape.


For those unfortunates who lack a VAXstation 3100 but are burdened by a suitable Intel-compatible system, here is the original DEC RZSPINUP utility program kit for DOS and Windows 3.x.

SG00000R.EXE - RZSPINUP kit (self-extracting ZIP file), which comprises the following files:

This kit was acquired from

Details like getting the program onto a DOS floppy and figuring out which one is "the ADAPTEC SCSI controller" [emphasis added] are left as exercises for the unfortunate.

Follow this link to more VAXstation 3100 material.

© 2023 Steven M. Schweda.