At 16:09 -0400 on 03/13/2015, Shmuel Metz (Seymour J.) wrote about
Re: Need assembler trick to quickly get second and third DS:
>I imagine that TRT was invented back in the day because so many
routines needed to parse on delimiters.
It's kind of clunky if you're only searching for one delimitor, but
it's sweet when you're looking for multiple delimitors or when you're
using it for something other than scanning.
I can attest to that. Years ago I worked in a company that replaced a
2540 with a 2501. The problem was that the 2540 was used at times to
read cards which had EBCDIC in some of the columns and Column Binary
in others. This was possible since the card could be read but not
feed into a hopper initially. Thus the EBCDIC read could be done
(with the bad codes checks suppressed) and then read and feed as
Column Binary. The 2501 was an unbuffered reader so we needed a way
of converting the EBCDIC columns from the Card Image EBCDIC to
Internal EBCDIC. I used a TR to move the odd bytes to one area
followed by the even bytes in the following area. Some TRs then
mapped rows 12/11/0/8/9 as separate bits and rows 1-7 as the low
order 3 bits. A OC of one area with the other then showed the Card
Image format (5 bits representing rows 12/11/0/8/9 as the high bits
with rows 1-7 being encoded as binary in the low bits). A TR then
converted into internal EBCDIC. The TRT was used as a sanity check to
insure that there was no more than one punch in rows 1-7. The mapping
TRs were repeated with a TR Table that mapped rows 1-7 as separate
bits followed by the OC and a TRT using a table checking for any
character with more then one bit on.
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