I have a problem with following 16-bit TASM program which evaluates the expression (ab+cd)/(a-d):
MyCode SEGMENT
ORG 100h
ASSUME CS:SEGMENT MyCode, DS:SEGMENT MyCode, SS:SEGMENT
Start:
jmp Beginning
a DB 20
b EQU 10
c DW 5
d = 3
Result DB ?
Beginning:
mov al, a
mov bl, b
mov dx,ax
mov al, BYTE PTR c
mov bl, d
mul bl
add dx,ax
mov al, a
sub al,bl
mov bl,al
mov ax,dx
div bl
mov Result, al
mov ax, 4C00h
int 21h
MyCode ENDS
END Start
The compilation errors I get in DOSBox console state that there's an undefined symbol (SEGMENT) and that the compiler can't address with currently ASSUMEd segment registers. It seems to me that that I'm missing the definition of a block, but I have no idea how to proceed further. What's wrong with this code?
I won't fix the logical errors for you, but the syntax in the top of this code is incorrect:
MyCode SEGMENT
ORG 100h
ASSUME CS:SEGMENT MyCode, DS:SEGMENT MyCode, SS:SEGMENT
Start:
You don't use the directive SEGMENT in the assume, they have to be removed. When removed the segments have to have a name applied to them. One is missing on SS:. It should look like:
MyCode SEGMENT
ASSUME CS:MyCode, DS:MyCode, SS:MyCode
ORG 100h
Start:
In DOS COM program all the segments for DATA, CODE, and the STACK are in the same segment. You can also achieve the same by replacing it with:
.model tiny
.code
ORG 100h
Start:
The TINY model is designed to work for DOS COM program creation. The ORG 100h directive has to be preceded by the .code directive. With this modification you have to remove this line:
MyCode ENDS