DOS ain't dead

EIDL version 1.0.0 released (Announce)

posted by Japheth , Germany (South), 20.02.2020, 13:16
(edited by Japheth on 20.02.2020, 13:42)

> See it as little ASM example, because it is not as advanced as all the
> other DOS idlers including Eric Auer's FDAPM.

Thanks!

I wonder a bit why the code sequence

   sti
   hlt

does work. In both docs, Intel & AMD, it is pointed out that the STI opcode will
have a "delayed" effect, so interrupts are enabled after the next instruction only. Obviously HLT is a special case.

It's also a mystery to me when and how often Int 28h is called. IMO it's called even if DOS is not "idle" at all. This little program below just displays a string via DOS until terminated by Ctrl-C. I runs significantly slower if EIDL (or any other idle tool) is installed.

;--- create binary with "jwasm -mz forever.asm"
        .286
        .model small
        .stack 1024

        .data
text db "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        db "abcdefghijklmnopqrstuvwxyz"
        db 0

        .code

start:
        mov ax, dgroup
        mov ds, ax
        mov si,offset text
        .while 1
                lodsb
                .if al == 0
                        mov si,offset text
                        lodsb
                .endif
                mov dl,al
                mov ah, 2
                int 21h
        .endw
        mov ah, 4ch
        int 21h

        END start


---
MS-DOS forever!

Complete thread:

• EIDL version 1.0.0 released - rr, 18.02.2020, 21:32 (Announce)
  • EIDL version 1.0.0 released - Japheth, 20.02.2020, 13:16
    • EIDL version 1.0.0 released - rr, 20.02.2020, 15:44
      • EIDL version 1.0.0 released - Doug, 20.02.2020, 19:20
        • EIDL version 1.0.0 released - rr, 20.02.2020, 20:34
    • EIDL version 1.0.0 released - rr, 20.02.2020, 17:54
      • EIDL version 1.0.0 released - Japheth, 21.02.2020, 20:23
        • EIDL version 1.0.0 released - rr, 21.02.2020, 21:57
          • EIDL version 1.0.0 released - Japheth, 22.02.2020, 03:14
            • EIDL version 1.0.0 released - rr, 23.02.2020, 19:10
              • EIDL version 1.0.0 released - Japheth, 24.02.2020, 19:04