jmp prob

[zak100]

Hi,
I want to use jmp to jump to following memory area 1000:0. I am using following statement:
jmp 1000:0h

I am getting following error:
D:\masm prog>ml /c btlder1.asm
Microsoft (R) Macro Assembler Version 6.14.8444
Copyright (C) Microsoft Corp 1981-1997.  All rights reserved.

Assembling: btlder1.asm
btlder1.asm(67) : error A2096: segment, group, or segment register expected

D:\masm prog>

Can somebody help me with this ?

Zulfi.

[MichaelW]

I can think of three methods ATM, but there are probably more.

Code Select Expand


.model small
.386
.stack
.data
 
    ;---------------------------------------
    ; For a far pointer the segment address
    ; must be in the high-order word.
    ;---------------------------------------

    fpdd dd 10000000h
    fpdw dw 0,1000h
   
.code
.startup

    push 1000h
    push 0
    retf

    jmp fpdd

    jmp dword ptr fpdw

.exit
end


[dedndave]

hi Zulfi
you can also create an empty segment and place a label in it
or - the old-fashioned way - hard code it - lol

FixedSeg SEGMENT AT 1000h

        org     0
BranchLabel:

FixedSeg ENDS
.
.
.
        jmp     BranchLabel

hard-code

        db      0EAh    ;JMP FAR
        dw      0       ;offset
        dw      1000h   ;segment

[zak100]

Hi,
I am using the hard coded sol of dedndave:
Some portion of code is given below:

Code Select Expand


mov ax, 1000h; read sector into address 0x1000:0
     mov es, ax
     xor bx, bx
     mov ah, 2; read sector function
     mov al, 1; read 1 sector
     mov ch,1;
     mov cl,2; reading 2nd sector
     mov dh, 0
     mov dl, 0
     int 13h
; --------------
     db      0EAh    ;JMP FAR
     dw      0       ;offset
     dw      1000h   ;segment

     
     



ORG 1FEH


        dw      0AA55h

;----------------------------------------------------------------------------------

        END     boot0



I am not getting the compilation error but I am getting a linker warning:

D:\masm prog>link16 /tiny btlder1.obj,btlder1.bin;

Microsoft (R) Segmented Executable Linker  Version 5.60.339 Dec  5 1994
Copyright (C) Microsoft Corp 1984-1993.  All rights reserved.

LINK : warning L4055: start address not equal to 0x100 for /TINY

D:\masm prog>
Is it a prob?
Can somebody plz help me with this?

Zulfi.

[MichaelW]

The warning would indicate a problem if the start address were supposed to 100h, which would be the case for a .COM file, but not for a boot sector.

[dedndave]

important to understand - it is a warning - not a hard error
it is more or less providing you with extra information
as long as you did not want it org'ed at 100h, you may ignore it