Sothe laserprinter understandsthe symbolJas 01001010,which we canalso
represent asthe decimal number 74 or the hexadecimal number 4A. We’ve
printed thisbyte vertically and horizontally below, showing how it adds up
to decimal 74 and hex 4A.
o x 27
1x 26
0x25
0x24
1x 23
0x22
1x 2’
ox
zone
0100
4
digits
1010
A
o
64
0
0
8
0
2
0
74 Decimal
Binary
Hexadecimal
The ASCII table in the Technical Supplement shows all these equivalent
representations for the symbols your laser printer understands. The table
organizesthem in ascending order. In fact, ASCII is organized in away that
actually makes sense.
Flip back there for aquick look right now. See how you can slicethe table
into clumps of 16 or 32, based on what’s in the zone portion under the
hexadecimal column? These clumps make subgroupsof similar symbols:
hex 00 to 1Farethe command symbols called control codes,
.hex 20 to 40 are the common keyboard symbols and numerals,
.hex 41 to 60 are capital letters and the less common keyboard
symbols,
.hex 61 to 7F are lowercase lettersand afew final symbols.
That takes care of the first 128 ASCII symbols. However, nearly every
computer and printer manufacturer treats the second half of the table
differently.Hewlett-Packard, for example,puts avarietyof accented foreign
languagecharacters into positions 128-255(oftenreferred to as /zighASCZl).
Epson gives you achoice of either italics characters or IBM character
graphics.
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