DOS ain't dead

Hello!

Does any anybody know, where is DOS have path and name of executed program?
I talk about paramstr(0) (in pascal) or first element of argv (in C) - like C:\PATH\COOLPRG.EXE

I am try disassemble minimal program in TP7, but have 31k disassembled text and continue investigate (may be somebody already known it and can make may path is short).

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Make DOS great again!

Carthago delenda est, Ceterum censeo Carthaginem delendam esse.

> Hello!
>
> Does any anybody know, where is DOS have path and name of executed
> program?
> I talk about paramstr(0) (in pascal) or first element of argv (in C) - like
> C:\PATH\COOLPRG.EXE
>
> I am try disassemble minimal program in TP7, but have 31k disassembled text
> and continue investigate (may be somebody already known it and can make
> may path is short).

I believe it is at the end of the environment block, after the double-zero that marks the end of the variables stored in the block.

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l

It is in PSP (program segment prefix)
Look at wikipedia article: https://en.wikipedia.org/wiki/Program_Segment_Prefix

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DOS-u-akbar!

Hello ecm,

> I believe it is at the end of the environment block, after the double-zero
> that marks the end of the variables stored in the block.

Indeed --- according to the all-knowing RBIL:
Format of environment block:
Offset  Size    Description     (Table 01379)
 00h  N BYTEs   first environment variable, ASCIZ string of form "var=value"
      N BYTEs   second environment variable, ASCIZ string
        ...
      N BYTEs   last environment variable, ASCIZ string of form "var=value"
        BYTE    00h
---DOS 3.0+ ---
        WORD    number of strings following environment (normally 1)
      N BYTEs   ASCIZ full pathname of program owning this environment
                other strings may follow
(This is under the entry for int 0x21, ah = 0x26.)

I wonder if there is a way to get the program name for DOS versions before 3.0.

Thank you!

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https://gitlab.com/tkchia · https://codeberg.org/tkchia · 😴 "MOV AX,0D500H+CMOS_REG_D+NMI"

> I believe it is at the end of the environment block, after the double-zero
> that marks the end of the variables stored in the block.

Thanks! It works!

---
Make DOS great again!

Carthago delenda est, Ceterum censeo Carthaginem delendam esse.