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Nowwewill calculatethevertical numerical valuesofthecolumnsofdots,
andenterthemunderneaththegrid.Eachverticalcolumnisfirstdivided
into
threegroupsof eightdots.Each groupof eightdotsis representedby one
byte,whichconsistsof eightbits.
This
iswherethenumbersdowntheleftsideofthegridcome in. Noticethat
thereis a numberfor each row of dots and that each numberis twicethe
numberbelow
it. Bymakingthesenumberspowersof two we can takeany
combinationof dotsin
a verticalcolumnandassignthem a uniquevalue.
Assigning the Index Table data
Unlikedefiningin the Standardmode,youmustassigntheIndexTablewith
the IBM mode.This IndexTableis preparedfor the informationof each
charactersattributedata,such
ascharactertype(Normal24-dothigh,or30-
dot high block graphics),the dot pattern data
in thememory, and the
compressionmaskbit data.
Eachcharacterrequires9 indextabledata.
Thefirstandthesecondbytes(ml andTn2)indicatesthepositionofthefirst
dotpattern
inthememory.ml isthehighorderbyte,andrn2istheloworder
byte.
Thethirdbyte,m-?,indicatesthecharacter
type andthedotpatterndatawidth
in thememory.
If the ch~acter
isnormal,simply enter the width of dot pattern inthe
memory.If the characteris a block graphic,add 128to the width of dot
patternin the memory.
Ourtelephonesymbolis
anormalcharacterandthewidthofthedotpattern
in thememoryshouldbe 25, so this
value is 25.
The fourthbyte,m4,indicatestheprintingattribute.
Thisbyteindicatesthecharacterwidthto beprinted,andinformationofthe
repetitiondotsfor blockgraphics“characters.
If the character
isa normalcharacter,add 192to the characterwidth.
If the character
isablockcharacter,anditshouldbeprintedasa linedraw
character,add64
to the characterwidth.Iftheblockcharacteris not a line
drawcharacter,thisbyteshouldbe the sameasthe characterwidth.
Ourtelephonesymbol
isanormalpicacharacter,so the characterwidthis
35,andthisbyteshouldbe 227.
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