Pass $1$:

begin

read first input' line

if OPCODE$=$ 'START' then

begin

save #$[$OPERAND$]$ as starting address

initialize LOCCTR to starting address

write line to intermediate file

read next input line

end $\{$if START$\}$

else

initialize LOCCTR to $0$

while OPCODE $$ 'END' do

begin

if this is not a comment line then

begin

$1f$ there is a symbol in the LABEL field then

begin

search SYMTAB for LABEL

if found then

set error flag $($duplicate symbol$)$

else

insert $($LABEL$,$ LOCCTR$)$ into SYMTAB

end $\{$if symbol$\}$

search OPTAB for OPCODE

if found then

add $3\{$instruction length$\}$ to LOCCTR

else if OPCODE $=$ 'WORD' then

add $3$ to LOCCTR

else if OPCODE $=$ 'RESW' then

add $3*$#$[$OPERAND$]$ to LOCCTR

else if OPCODE $=$ 'RESB' then

add # $[$OPERAND$]$ to LOCCTR

else if OPCODE$=\text{'}BYT{E}^{\text{'}}$ then

begin

find length of constant in bytes

add length to LOCCTR

end $\{$if BYTE$\}$

else

set error flag $($invalid operation code$)$

end $\{$if not a comment$\}$

write line to intermediate file

read next input line

end $($while not END$\}$

write last line to intermediate file

save $($LOCCTR $-$ starting address$)$ as program length

and $\{$Pass $1\}$

Figure $2\mathrm{.}4($a$)$ Algorithm for Pass $1$ of assembler.

Write c$++$ code for this algorithm $..$please i want simple code