===========================LISTING 1============================

;X% = ASC(MID$(Work$, Y%))
MOV AX,OFFSET WORK$ ;get the address for Work$
PUSH AX ;push that onto the stack
PUSH WORD PTR [Y%] ;push the value of Y%
MOV AX,7FFF ;load AX with 7FFFh (32767)
PUSH AX ;push that as well
CALL B$FMID ;call the BASIC MID$ routine
PUSH AX ;push the address MID$ returns
CALL B$FASC ;call the BASIC ASC routine
MOV WORD PTR X%, AX ;assign the value ASC returns

===========================LISTING 2============================

FOR X% = 1 TO 100
Y% = X%
NEXT

;FOR X% = 1 TO 100
B80100 MOV AX, 1 ;assign AX = 1 to initialize the loop
E90400 JMP 003A ;jump into NEXT at address 003A
;Y% = X%
0036:
A33600 MOV WORD PTR [Y%], AX ;assign Y% from AX ;NEXT
40 INC AX ;increment AX
003A:
A33800 MOV WORD PTR [X%], AX ;assign X% from AX
3D6400 CMP AX, 64 ;64 Hex = 100 Decimal
7EF4 JLE 0036 ;jump if less or equal

===========================LISTING 3============================

X% = 1
DO WHILE X% <= 100
Y% = X%
X% = X% + 1
LOOP

;X% = 1
C70636000100 MOV WORD PTR [X%], 1 ;assign X% = 1
;DO WHILE X% <= 100
0036:
833E360064 CMP WORD PTR [X%], 64 ;compare X% to 100
7E03 JLE 0040 ;jump if less/equ.
E90C00 JMP 004C ;else we're done
;Y% = X%
0040:
A13600 MOV AX, WORD PTR [X%] ;assign AX from X%
A33800 MOV WORD PTR [Y%], AX ;assign Y% from AX
;X% = X% + 1
FF063600 INC WORD PTR [X%] ;increment X%
EBEA JMP 0036 ;jump back in
004C:
;program continues

===========================LISTING 4============================

IF X% > 100 THEN
Y% = 2
ELSEIF Z% < 1 THEN
Y% = 3
ELSEIF X% < 0 THEN
Y% = 4
END IF


;IF X% > 100 THEN
833E360064 CMP WORD PTR [X%], 64 ;is X% > 100?
7F03 JG 003A ;yes, jump ahead
E90900 JMP 0043 ;no, keep checking
;Y% = 2
003A:
C70638000200 MOV WORD PTR[Y%], 2 ;assign Y% = 2
E92300 JMP 0066 ;done, jump out
;ELSEIF Z% < 1 THEN
0043:
833E3A0001 CMP WORD PTR [Z%], 1 ;is Z% < 1?
7C03 JL 004D ;yes, jump ahead
E90900 JMP 0056 ;no, keep checking
;Y% = 3
004D:
C70638000300 MOV WORD PTR [Y%], 3 ;assign Y% = 3
E91000 JMP 0066 ;done, jump out
;ELSEIF X% < 0 THEN
0056:
833E360000 CMP WORD PTR [X%], 0 ;is X% < 0?
7C03 JL 0060 ;yes, jump ahead
E90600 JMP 0066 ;no, bag out
;Y% = 4
0060:
C70638000400 MOV WORD PTR [Y%], 4 ;assign Y% = 4
;END IF
0066:
;program continues

===========================LISTING 5============================

;IF LEN(Work$) > X% + 14 THEN Z% = 1
MOV AX, WORD PTR [X%] ;put the value of X% into AX
ADD AX, 0E ;add 14 decimal (X% + 14)
MOV BX, AX ;save the result in BX
MOV AX, OFFSET Work$ ;get the address of Work$
PUSH AX ;push it for LEN below
MOV [BP-0C], BX ;save BX for a moment
CALL B$FLEN ;call BASIC's LEN routine
CMP AX, [BP-0C] ;compare LEN in AX to what we
; evaluated and saved earlier
JG 005F ;it is greater, jump to assign
JMP 0065 ;it's not greater, jump over
005F:
MOV WORD PTR [Z%], 1 ;assign Z% = 1
0065:
;program continues

===========================LISTING 6============================

Not recommended:

IF X% + 14 < 100 THEN 'BASIC evaluates X% + 14 here
Y% = 2
ELSEIF X% + 14 = 100 THEN 'and then again here
Y% = 3
ELSEIF X% + 14 > 100 THEN 'and again here too
Y% = 4
END IF

Much better:

SELECT CASE X% + 14 'BASIC evaluates X% + 14 once.
CASE < 100 'All of these tests are then
Y% = 2 ' performed on the results
CASE 100 ' of the first evaluation.
Y% = 3
CASE > 100
Y% = 4
END SELECT

SELECT CASE is therefore similar to:

Temp% = X% + 14
IF Temp% < 100 THEN
Y% = 2
ELSEIF Temp% = 100 THEN
.
.