flat assembler
Message board for the users of flat assembler.
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HyperVista 04 Aug 2006, 19:45
Hello leo128
ES stands for Extra Segment and is one of a handful of segment registers and can be used to specify a location in memory. The colon between ES and BX (ES:BX) denotes the standard segment:off-set address notation. In otherwords, ES:BX specifies a memory location that is the value contained in BX "distance" from the start of the segment ES. |
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leo128 05 Aug 2006, 19:22
All Right! Thank you!
So, let see if I got it... CS --> Code segment (points to a segment in which the program code resides) DS --> Data segment (points to a segment in which the program is expected to store its data) ES --> Extra segment register used for addressing memory without modifying other registers, for example DS. so, if I make ES match CS, I can read data from disk and tell int 13 to store data in the code segment, and I have to pay attention not to overwrite the program code itself... so, actually, because I'm not yet an expert ASMer, I tried mov ax, cs mov es, ax and it worked fine... so at the moment I use labels to make room for my data. anyway, I think I could have done this with any other memory segment (like DS...) to make it accessible via ES. is all this right? did I get it? I hope so... anyway... my interrupt 13 call seems to work fine now, except that it fails returning an error code in AH (code = 80h, which seems to mean "Disk Timeout"). When I issue the int 13 call, the MS-DOS 16 bit subsystem of windows XP tells me that int 13 is unsupported, and the application might not work as expected. I just click "Ignore" and it goes stright to the failure (CF = 1, AH = 80h) so my doubt is... can I use int 13h, function 02h in my environment, or I'll have to do something, like install windows 98 or MS-DOS 6.22 ??? maybe I passed it wrong cyl/head/sect parameters... or even... do I have to use another interrupt ??? thank you again!!! |
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DOS386 22 Dec 2006, 02:58
Accidentally found this (OK, not newest) thread with open questions.
Quote:
NO. Quote:
DOS. FreeDOS or Enhanced DR-DOS ![]() Quote:
Install DOS first. Also, CHS works up to 8 GB maximal. Quote:
NO. Use this one but be careful not to overwrite something on the HD. ![]() _________________ Bug Nr.: 12345 Title: Hello World program compiles to 100 KB !!! Status: Closed: NOT a Bug |
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