NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/comp/os/misc/994

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From: [e-mail] (Bill Morrow)
Subject: Help on RT-11 macro language
Sender: [e-mail] (USENET News System)
Message-ID: <[e-mail]>
Date: Mon, 04 Jan 93 22:33:05 GMT
Nntp-Posting-Host: cns16.cns.ucalgary.ca
Organization: University of Calgary
Keywords: RT-11, macro
Lines: 38

Hello all you old fellows,

I have been forced to update some of the PDP-11 assembler acquisition
software running on our old RT-11 system. Of course,
there are no comments in the source, to save on disk space.
A week ago, I knew absolutely nothing about PDP-11 macro language.
I have been wading through the "Orange Wall", but
I'm a bit confused by the unconditional branch instruction -
where does this code end up after the 'BR 10$+2' step?

DR3INT: 0
    BR    10$+2        <--- branch to where ?
    BR    20$+2
10$:    MOV    #107,DMACSR
    TST    ADCO        <--- here ?
    BEQ    11$
    MOV    #113,KWREG
11$:    MOV    DR3INT+4,DR3INT
    TR            <--- or here ?
12$:    et cetera ad nauseum

My intuitive guess is that it ends up at 'TST ADCO',
but the manual seems to be telling me it branches to
the indicated address.

While you're here, does the 'MOV' instruction at 11$ really move
the label 'DR3INT' to the same address as 10$? Why is the
'BR 20$+2' there then?

What does 'TR' do? I can't find it in the instruction set
or the macro language reference manual.

Thanks for the help.
--
__________________________________________________________
Bill Morrow                    voice: [phone]
Clinical Neurosciences         fax: [phone]
University of Calgary          e-mail: [e-mail]