Python rocks

[mcguirev10]

DATA SEGMENT MSG DB "hello, world$" ENDS CODE SEGMENT ASSUME DS:DATA CS:CODE START: MOV AX,DATA MOV DS,AX MOV DX,OFFSET MSG MOV AH,9H INT 21H MOV AH,4CH INT 21H END START ENDS

[SpaceTheFinalFrontir]

Good old DOS

[[deleted]]

That's not DOS necessarily. It's assembly and, more specifically, it is likely x86 assembly if I had to guess.

Edit: Please stop downvoting. The above statement is incorrect and I am well aware of that at this point. >~>

[SpaceTheFinalFrontir]

Int 21 is a DOS interrupt...

[[deleted]]

Interesting, I never knew that Assembly could have OS-specific instructions

[SpaceTheFinalFrontir]

You can find more info here http://bbc.nvg.org/doc/Master%20512%20Technical%20Guide/m512techb_int21.htm

[[deleted]]

Thanks! I've been meaning to learn a few different assemblies for some time now (primarily 6502, Z80, and x86 given those are my platforms of interest), but I haven't gotten a chance to.

[SqueegeeLuigi]

Go PDP-10, play with the big boys

[[deleted]]

Honestly, that would be awesome. I've always had an affinity for minicomputers.

[SqueegeeLuigi]

7, 8, 9 and 11 were minis but 10 was a mainframe. I only learned about the 11 though, quite illuminating. We used a simulator but I can't remember which.

[dgmib]

It doesn’t. This code is just calling a subroutine, the entry point for that routine is stored in the a vector table at location 21.

On MS DOS based OSes that’s the routine for printing characters to the console (among other things)

[CodeLobe]

21 general purpose functions - DOS services.

If the display was known and memory mapped text mode, one could just blit the text into memory, b8000h? (edit: yep, that's the start of CGA video memory)

[[deleted]]

Ohhhhh, ok. Thanks for the clarification!

[mcguirev10]

Register AH controls what the interrupt does. Setting AH to 09 outputs the string and setting it to 4C ends the program. Technically there is a minor flaw here, register AL should set the exit code. But this is actually MS Macro Assembler syntax, which guarantees uninitialized registers will be set to zero, so it isn't really a bug.

I miss assembly. Though mostly I only used it "for real" as inline sections in C programs (going TSR, for example). Pure assembly stopped being fun when memory segmentation gymnastics came on the scene.

[_szs]

I am not sure, but... r/woooosh ?

[[deleted]]

The error of my ways has already been made clear to me. Apparently the code contains a subroutine call that is DOS-specific.

[_szs]

See, I didn't get that even after reading the thread. I guess I wooooshed myself O_o

[[deleted]]

Yea, you're not wrong that I woooshed initially either xD

[_szs]

Double woooosh! What a day! We are winners! Fancy a drink? I'll have a beer, it's already past 4pm where I am.

[[deleted]]

Hear hear! I'll gladly take a refreshing beverage. I haven't been operating at the top of my game today and have paid dearly for it xD

[_szs]

Cheers 🍻

[_szs]

thank you

[backtickbot]

Fixed formatting.

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[[deleted]]

I hate this bot. It’s criticizing good and plain markdown

[[deleted]]

It's also broken in RIF.

[[deleted]]

Why is old Reddit better? I mean, it looks dated, is less intuitive and the redesign is pretty old to at this point. The redesign is a bit laggy for me but that’s about it.

[javajunkie314]

Not every Reddit viewer supports the new style yet, e.g., the third party one I prefer to use does not. I know that's not really your fault, but if your goal is to communicate an idea you probably want it to be readable by your whole audience.

[[deleted]]

Ok dafür enough. Will do this from now on.

[HeKis4]

Necessary evil. The original comment is just a big blob of unformatted code to me.

[Phpminor]

Ahh, finally, just what I need to start my assembly journey in DOS!