• Truly amazing

    From Robert Prins@21:1/5 to All on Tue Apr 20 15:55:14 2021
    Just came across this one:

    C4 1C 9F AB 47 47 EB F9

    Save as a .COM file and run it, even in DOSBox-X. (Do a CLS before you start it)

    Comparable to a gem like "+[>,]+[<.-]" in that language that usually has an '*' in it's name. ;)

    Robert
    --
    Robert AH Prins
    robert(a)prino(d)org
    The hitchhiking grandfather - https://prino.neocities.org/indez.html
    Some REXX code for use on z/OS - https://prino.neocities.org/zOS/zOS-Tools.html

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From wolfgang kern@21:1/5 to Robert Prins on Tue Apr 20 16:52:58 2021
    On 20.04.2021 17:55, Robert Prins wrote:
    Just came across this one:

    C4 1C 9F AB 47 47 EB F9

    Save as a .COM file and run it, even in DOSBox-X. (Do a CLS before you
    start it)

    Comparable to a gem like "+[>,]+[<.-]" in that language that usually has
    an '*' in it's name. ;)

    Robert

    I can't recommend to do this!

    endless:
    LES BX,[SI] ;SI=?? may depend on environment
    LAHF ;who knows what's in the flags ?
    STOSW ;WRITE to ES:DI (try to use cc-flags for color)
    INC DI dup2 ;stosw does this also
    JMP $-7 ;endless or until crash

    BX isn't used.
    And if SI doesn't point to the screen-seg it writes to another 64KB block.
    __
    wolfgang

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Kerr-Mudd,John@21:1/5 to nowhere@nospicedham.never.at on Wed Apr 21 11:12:28 2021
    On Tue, 20 Apr 2021 14:52:58 GMT, wolfgang kern
    <nowhere@nospicedham.never.at> wrote:

    On 20.04.2021 17:55, Robert Prins wrote:
    Just came across this one:

    C4 1C 9F AB 47 47 EB F9

    Save as a .COM file and run it, even in DOSBox-X. (Do a CLS before
    you start it)

    Comparable to a gem like "+[>,]+[<.-]" in that language that usually
    has an '*' in it's name. ;)

    Robert

    I can't recommend to do this!

    endless:
    LES BX,[SI] ;SI=?? may depend on environment
    LAHF ;who knows what's in the flags ?
    STOSW ;WRITE to ES:DI (try to use cc-flags for color)
    INC DI dup2 ;stosw does this also
    skips next scrn char

    JMP $-7 ;endless or until crash

    BX isn't used.
    except to set es.

    And if SI doesn't point to the screen-seg it writes to another 64KB
    block. __
    wolfgang



    I presume it's meant to put stripes down the screen; but al is 0 at start;
    aha! I see the jmp goes to 101, which becomes SBB al,9F

    I thought a .COM file at startup has bx=0x0000,si=0x0100,di=0xFFFE,
    es=ds=cs;
    LES must somehow pick up the Screen seg.



    OK it's a mini 'Matrix' tribute. Nice.

    --
    Bah, and indeed, Humbug.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From wolfgang kern@21:1/5 to John on Mon Apr 26 14:43:24 2021
    On 21.04.2021 13:12, Kerr-Mudd,John wrote:
    On Tue, 20 Apr 2021 14:52:58 GMT, wolfgang kern <nowhere@nospicedham.never.at> wrote:

    On 20.04.2021 17:55, Robert Prins wrote:
    Just came across this one:

    C4 1C 9F AB 47 47 EB F9

    Save as a .COM file and run it, even in DOSBox-X. (Do a CLS before
    you start it)

    Comparable to a gem like "+[>,]+[<.-]" in that language that usually
    has an '*' in it's name. ;)

    Robert

    I can't recommend to do this!

    endless:
    LES BX,[SI] ;SI=?? may depend on environment
    LAHF ;who knows what's in the flags ?
    STOSW ;WRITE to ES:DI (try to use cc-flags for color)
    INC DI dup2 ;stosw does this also
    skips next scrn char

    JMP $-7 ;endless or until crash

    BX isn't used.
    except to set es.

    And if SI doesn't point to the screen-seg it writes to another 64KB
    block.

    I presume it's meant to put stripes down the screen; but al is 0 at start; aha! I see the jmp goes to 101, which becomes SBB al,9F

    yeah, I saw it but forgot to mention where AL get its value.

    I thought a .COM file at startup has bx=0x0000,si=0x0100,di=0xFFFE,
    es=ds=cs;
    LES must somehow pick up the Screen seg.

    if DS:SI points to CS:0100 then ES:BX read as AB9f:1cc4 which is at the
    end of in the graphics-RAM range (nothing to see in text mode) but it overwrites part of the VideoBIOS (it may be RAM-mapped and writable).

    OK it's a mini 'Matrix' tribute. Nice.
    I cannot try such here.
    __
    wolfgang

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)