29 Dec
2002
29 Dec
'02
12:43 p.m.
On Sun, 29 Dec 2002, Sellam Ismail wrote:
The way I'm thinking to do it is to first
determine what grouping the
character being read is in. It is either going to be in the 12, 11, or 0
"zone", or in the extended characters, the 8-3 zone. And then there are
the extended IBM character sets (i.e. EBCDIC) where you have 8-x zones
where x can be any number. What these represent is the 8 and x columns
being punched together as a sort of "meta" code (kinda like a control key
on a keyboard).
And I forgot to mention the really funky codes that combine two of the 12,
11, 0 zones and multiple rows to form special characters (like 12-0-1-8-9
for NUL in standard IBM EBCDIC).
Then, there will be 1-9 possible characters in each
zone. After
determining the zone, finding the correct character will be a matter of a
simple table lookup. The table will contain the ASCII character code of
that character, and then off that goes over the serial port to the
receiving machine (or buffered in some manner).
The idea is to create a character set template for each known set that can
be loaded before each batch to be read. The template will include the
exceptions like where multiple rows are punched for meta characters. Then
it will be a simple matter to translate the code to the appropriate ASCII
equivalent.
Sellam Ismail Vintage Computer Festival
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