26 Jul
2005
26 Jul
'05
1:59 a.m.
Tony Duell wrote:
I have the 9826/9836 service manual from Jon Johnston
(the chap who runs
hpmuseum.net). It's a boardswapper guide, of course, but with some useful
information in it (read : stuff that would take more than 10 seconds to
work out from looking at the mahcine). It's often the way with HP service
manuals, much of it is obvious, but there's often something that really
helps with understanding the machine if you read it with a hackish eye.
Even the programmers found HP software manuals to be that way.
Copied from <http://www.robelle.com/smugbook/manual.html>:
How to Read a Manual
By Alfredo Rego
Adager
Sun Valley, Idaho
March 1, 1982
----------------------------------------------------------------------
What follows is Alfredo's answer to a question from the audience at a
RUG meeting. The question was: "Do you have the IMAGE hashing
algorithm?" Alfredo detected the question behind the question and made
this reply.
----------------------------------------------------------------------
You should read manuals like you read love letters.
In a love letter, everything counts. You read between the lines, above
the lines, below the lines, and in the margins. You read between the
individual letters (is that "i" dotted in an angry way?) You wonder
what significance the stamp has. You smell the envelope for any
special fragrance. You study the salutation (why "dearest" and not
"darling" this time?) You even try to take the sheets of paper apart!
In a manual, everything counts as well. Your heart may not pound as
strongly when you read a manual. But you will certainly have more time
for love if you do not have to spend endless hours at the computer
doing things that you would not have to do at all had you read the
manual lovingly to begin with!
A sample from the IMAGE/3000 manual will warm up you heart:
The manual mentions that DBGET "provides eight different methods for
reading the data items of a specified entry". It then specifies these
reading methods according to the Mode parameter. Everybody seems to
register the first seven modes and everybody seems to ignore the
eighth mode, whose action the manual casually describes thus:
"Read the entry occupying the primary address of a synonym chain using
the search item value specified in ARGUMENT to locate the entry. If
the entry is not a primary entry in a master data set specified by
DSET, it is not read."
This apparently innocent paragraph actually says a lot! For instance,
it says that you can use a Read-Before-Write approach that can help
you minimize the load time of a master data set.
Specifically, if you have to load a large quantity of entries to a
master data set, you can do a DBGET mode 8 on the search-item value
corresponding to the entry you are about to DBPUT.
If DBGET returns a No Entry error code, then you know that the entry
will be a primary entry and will never have to be migrated; therefore,
you can do its DBPUT with a clear sense of righteousness.
If, however, DBGET returns a code that means that it found an entry in
the spot where your proposed entry belongs, then you know that it
would become a secondary somewhere and -- even worse -- you know that
it would become a candidate for migration if some primary later on
happens to belong in the temporary spot "lent" to it.
With this knowledge, you are then free to choose not to DBPUT this
entry on this pass but wait until you have loaded all the
primaries. You can then do a second pass loading all the secondaries
-- none of which will migrate at all!
The savings in time can be measured in the order of days. Well worth
your while during your manual-reading, even though it was not your
personfriend who wrote it.
Alfredo Rego
(end quote)