On Wed, 31 May 2023 21:28:34 -0700, Michael Stein wrote:
>
> ... So any SVC number ending in 0 resulted in a
>last character of x'c0' or '{'.
>
>from: MVT source pds AAPVT member IEATRANS
>
>TRANSVC LH RWORK3,SVCID(RRB) . GET SVCID
> CVD RWORK3,SVCNAME . CONVERT SVC NUMBER TO DECIMAL
> UNPK SVCLPANM+4(4),SVCNAME+5(3) .UNPACK TO 4 DIGITS
>
That could have been fixed with a simple "OI X'F0', SVCLPANM+7", but
storage was precious in the day.
>While SVCLIB was a PDS with a directory as normal, for performance
>reasons, modules were NOT usually locaed by name. Instead a module which
>transfered control to another had the name along with a place for the TTR
>(disk address) of the target module.
> ...
>So transient area "program fetch" just had to read the block
>(at most 1K) from the specified TTR...
>
Did it do a proper check for I/O completion, or just rely on bit-spinning?
I recall a PDP-8 paper tape bootstrap loaded that kept reading until it
overlaid an instruction with a branch to the loaded program.
> There was a program which had to
>be run anytime SVCLIB was reorganized which used the names to update
>all the TTRs in the SVC modules. Also the SVC table entry for SVCs
>not in link pack contained the TTR of the module.
>
Backup recommended.
--
gil
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