x86-16

When studying programming 8085, 8086 and microporcessors in general we always have hexadecimal representation. Its ok that binary numbers are important in computers. But how these hexadecimal numbers are important? Any historical importance? It would be nice if someone point to some historical papers also. EDIT: How computers handle hexadecimal numbers? For example what happens in 8085 when a hexadecimal number is given as input? Hexadecimal has a closer visual mapping to the various bytes used to store a number than decimal does. For example, you can tell from the hexadecimal number

In the 8086 architecture, the memory space is 1 MiB in size and divided into logical segments of up to 64 KiB each. i.e. it has 20 address lines thus the following method is used: That the data segment register is shifted left 4 bits then added to the offset register My question is: How we do the shift operation although all the registers are only 16 bits Address translation is done internally by a special unit without using the registers available to user code to store intermediate results - it just fetches 16-bit values and does the translation inside - it is not reflected anywhere where the

I am going through some example assembly code for 16-bit real mode. I've come across the lines: mov bx, cs mov ds, bx mov si, OFFSET value1 pop es mov di, OFFSET value2 what is this doing? What does having 'OFFSET' there do? Nathan Fellman As some of the other answers say, the offset keyword refers to the offset from the segment in which it is defined. Note, however, that segments may overlap and the offset in one segment may be different in another segment. For instance, suppose you have the following segment in real mode data SEGMENT USE16 ;# at segment 0200h, linear address 2000h org 0100h

I've been messing around with x86-16 assembly and running it with VirtualBox. For some reason when I read from memory and try to print it as a character, I get completely different results from what I was expecting. However when I hard-code the character as part of the instruction, it works fine. Here's the code: ORG 0 BITS 16 push word 0xB800 ; Address of text screen video memory in real mode for colored monitors push cs pop ds ; ds = cs pop es ; es = 0xB800 jmp start ; input = di (position*2), ax (character and attributes) putchar: stosw ret ; input = si (NUL-terminated string) print: cli

I have been writing kernel in C. I've been using the GCC cross-compiler, writing on a Windows system and targeting 16bit Real Mode. I don't have the C library available to write the kernel. I have started with some code which is suppose to print a character directly to the screen. Here is a function from kernel.c : int main() { char *src = (char *)0xB8000000L; *src = 'M'; src += 2; *src = 'D'; return 0; } I compiled my code using GCC with the parameter -m16 to generate code that will run in real mode. I use these commands to generate my kernel.bin : gcc -ffreestanding -c -m16 kernel.c -o