.ps 10
.vs 14
boxht = boxht * 2
boxwid = boxwid * 2
arrow "source" "code"
LA: 
box "lexical" "analyzer"
arrow "tokens" above
P: 
box "parser"
arrow "intermediate" "code" 1.3
Sem: 
box "semantic" "checker"
arrow
arrow <-> up from top of LA
LC: 
box "lexical" "corrector"
arrow <-> up from top of P
Syn: 
box "syntactic" "corrector"
arrow up
DMP: 
box "diagnostic" "message" "printer"
arrow <-> right from right of DMP
ST: 
box "symbol" "table"
arrow from LC.ne to DMP.sw
arrow from Sem.nw to DMP.se
arrow <-> from Sem.top to ST.bot