From: system@SendSpamHere.ORG
Sent: Tuesday, July 06, 1999 6:03 AM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: ZDEC for OpenVMS Alpha V7.x?

In article <3780B904.193303D4@winternet.com>, Ed Wilts <ewilts@winternet.com> writes:
>I've got an old ZDEC.MAR utility dating back many years that has served
>me well over the years.  Yesterday, I built it on a V7.1-2 system, and
>although it compiled/linked without any problems, when zeroing a device
>error count, it did it a little more aggressively than I would have
>liked (can you say bugcheck boys & girls?)...
>
>Does anyone have a utility that zeros device error counts for V7.1?  An
>internals programmer I am not.

Yes!  Use DELTA!

The process is rather simple.  Run the system dump analyzer (SDA) and
issue the SDA command:

SDA> SHOW DEVICE ddcn:     (where ddcn: is the device you want to zero)

Then, evaluate the address of its UCB's error count field.

SDA> EVALUATE UCB+UCB$L_ERRCNT  (on Alpha)
SDA> EVALUATE UCB+UCB$W_ERRCNT  (on VAX)

This will return a hexadecimal value which is the system space address
of the error count field for the device.  You can now ZAP this value by
running DELTA.  I typically do so by spawning DELTA from within SDA as
follows:

SDA> SPAWN RUN SYS$SHARE:DELTA

Then you run DELTA on an Alpha, you will get an initial display that is
an instruction.  For example:
-----
OpenVMS Alpha DELTA Debugger

Exit 00000001

80058F80!       LDQ             R28,#X0008(SP)
-----

On a VAX, you'll get only a version identification message such as:
-----
DELTA Version 5.0
-----


At this point, enter:

1;M    and a carriage return


there's no prompting.


On VAX only, enter 

[W    (this will set the scope of DELTA to 16 bit words because the
       UCB's error count field is a word on VAX)


Then, it's time to clear the error count.  Enter:

00010001:<hexadecimal-address>/
                              ^---
When you enter the "/", DELTA will return the contents of this system
space address (in hexadecimal) which is the error count for the device.
Simply follow the result with a zero (0) and a carriage return.   The
<hexadecimal-address> is the value from the SDA exercise just prior to
invoking DELTA.  As an example, for a device with 10 errors you would
see:

00010001:8106DC88/0000000A 0 <cr>
                           ^--- zero+<cr> entered to clear error count
                  ^^^^^^^^----- current error count of device in hex.
                 ^------------- displays contents at specified address
         ^^^^^^^^-------------- hex. address of UCB's error count field
^^^^^^^^----------------------- IPID of SWAPPER process (command format
                                requires IPID and SWAPPER's is 00010001)

Note: On a VAX, if the [W command has been issued, the above would dis-
play as:

00010001:8106DC88/000A 0 <cr>

When you're done, type EXIT and a carriage return.
 
I've posted this little exercise here many times, shouldn't this be in
the FAQ by now???  

--
VAXman- OpenVMS APE certification number: AAA-0001           VAXman@TMESIS.COM

"Now what else is the whole life of mortals but a sort of comedy, in which the
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