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  1. DDA Lines with 1 Byte Error Accumulators

    For the past couple of weeks I've had my head metaphorically underwater as I drown myself in writing hardcore assembly for the first-time in two CGA routines: line and filled-triangle drawing. Both of these are based on Bresenham's algorithms which are fundamentally referred to as DDA (digital differential analyzers) and use the concept of integer error accumulators in order to approximate a line via pixels. Consider these two lines:

    Click image for larger version. 

Name:	line-00-77.png 
Views:	1 
Size:	414 Bytes 
ID:	37253 <-- (0,0) to (7,7)
    ...

    Updated Today at 11:55 AM by neilobremski

    Tags: bresenham, debug Add / Edit Tags
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    Asm
  2. Very Rare Find For Me!

    Quote Originally Posted by Havoc View Post
    I visit my local Thrift store a few times a month, this time I was in for a surprise. See it on YouTube here: https://www.youtube.com/watch?v=gTiWRSQMHpc
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  3. The Story of LucasFilm Games (Part I) | It's a Pixel THING - Ep. 114

    Lucasfilm Games, later known as LucasArts, was one of my favorite video game developers and publishers since its early years.
    This is their story.

    The Story of LucasFilm Games (Part I) | It's a Pixel THING - Ep. 114
  4. ES Segment Prefix Override

    It's possible to override the implied segment of an instruction with a prefix. I was trying to figure out how to do this in DEBUG, specifically to copy the byte at ES:[DI] into AL. I couldn't figure out the correct syntax and the MSDN reference was not helping. I finally just looked up the machine code of such a prefix (26h) and then looked at what DEBUG disassembled it as:

    Code:
    0100 BF0301	MOV DI,0103	; set DI to next instruction byte
    0103 26		ES:		; 26h = ES segment prefix override
    ...
    Categories
    Asm
  5. Software written in DOS DEBUG

    The DEBUG utility included with DOS (and FreeDOS) is an awesome experimental and hobbyist programming platform, but can it be used for professional programs and full blown software? I think so.

    My first computer programming was done on Apple II's during a special class in elementary school. I still don't know how I got put into it but we used LOGO to do cool graphics shit with the "turtle". I don't remember much from this period. Later, my mom got a monochrome IBM AT 8088 ...
    Tags: debug Add / Edit Tags
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    Asm
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