popa | solved user requirements in Yangon who want to hire taxi

I'm new to C, and I've been given a question to write a program to check palindrome words. I did the following code, it gives an output. but the output is always "No". The idea of what I did in this code is, I first divided the string and pushed them into one stack (stacka). then pushed the rest of the letters to another stack(stackb). Then I pop both of those stacks and check whether the letter returning from each pop function(of stacka and stackb) is equal or not. if not it will return 0. below is the code. Thank you in advance. Have a nice day!.

I'm new to all this, so I apologize in advance if I missed something really obvious

So, I'm trying to make a simple kernel in x86 assembly and C. I was trying to get interrupts working. I am defining the GDT, IDT in assembly.

I'm not even sure what's wrong, the GDT or the IDT. The thing is, everything seems fine until I actually trigger an interrupt.

I checked OSDev, the Intel Manuals, James Molloy's guide, and random blog posts, and I just can't figure this out.

Here's the code:

I'm trying to write an assembly function to convert ASCII decimal digits into hexadecimal values which can be easily used by the computer. Before showing my code, I have to point out that I'm working in 16-bit real mode (using AT&T syntax), therefore I have some limitations.

To achieve my goal, I wrote a "power" function which takes two arguments (BX as the base and CX as the exponent) and returns BX^CX into BX, or at least that's what I expected it to do. In reality, it works fine only once. For example:

I am trying to learn some x86 assembly. I have successfully created a MBR with a bootloader, loaded another sector, switched to Protected Mode and performed a far jump into the loaded sector.

I am using NASM on a 64-bit Windows installation and assembling with nasm -s -f bin bootloader.asm -o test.img. I load the test.img file into a VirtualBox VM as a floppy.

I have written a subroutine (subroutine definition in code section) that uses lodsb to load characters from ESI which I have previously pointed to a label using mov esi, _LOW_KERNEL_MESSAGES_TEST (where _LOW_KERNEL_MESSAGES_TEST is a label defined to db "Hello, World!", 0). However, this does not print anything.

Neither does mov al, [_LOW_KERNEL_MESSAGES_TEST] which was expected to print the first character 'H' (character printing subroutine takes AL as character input)

Directly moving a character into AL by mov al, 't' and then calling the one character printing subroutine works fine, I have also tested the offset and successfully printed the word 'Test', the problem lies only in the "move label into esi and then load it into al" part of the printing

• Offsetting the label by various constants I found in the bootloader
• Printing the first character (as mentioned with mov al, [_LOW_KERNEL_MESSAGES_TEST]]
• Commenting sections of the printing subroutines
• Modifying the far jump and GDT in bootloader
• Using popad instead of popa (thought the AX register was being modified?)

As per the request of the kind commenters below, I have attempted to create a minimal reproducible example, code for which can be found here:

https://pastebin.com/PaeLErDU

This can further be assembled by using:

nasm -s -f bin .asm -o floppy.img

By binding this floppy.img file to a floppy controller in a VirtualBox 6.1 VM

and running it, a completely black screen appeared with a white cursor in the top left corner and the VM stalled, with a "critical error has occured" message, the error log does not make much sense to me but might be helpful, it can be found at https://pastebin.com/g1C2xf7V

My files:

bootloader.asm:

I've got 8 different data sets popA, popB, popC, popD, popE, popF, popG, and popH for the growth rates for years of a particular city. Each data sets contains a column for the year (labelled Period and a column for the growth rate (labelled A for popA, B for popB and so on).

Sample data for ```popA` as follows:

I want to print "Hello." every 55ns. what am I doing wrong?

I am currently in the process of fixing a bootloader I wrote to load my custom real-mode x86 kernel (SYS.BIN). I managed to get it to read the root directory and FAT, and load a small-ish kernel from the filesystem, all within the bootsector. However, I began testing it with larger kernels, and it seems that the bootloader will not load more than one cluster. I checked my code against another similar bootloader, and it seems to be doing effectively the same thing when it comes to loading multi-cluster files. The main difference is that I am loading the first FAT into segment 0x3000 and the root directory into segment 0x3800, so that they will be accessible to the kernel. (Did I mess up segmentation at all?)

I should probably mention that I'm testing this by compiling with NASM, writing the resulting BOOT.BIN file to the first sector of a raw 32M image, mounting it on a loop device, copying SYS.BIN over, and creating a new image of that loop device, which I then throw into QEMU as a hard drive. I know with certainty that it is only loading the first cluster of the file.

In particular, I believe the code that is causing the issue is likely in here:

I have done my research and stumbled upon many solutions to change some characters of the string. I am trying to print a hex code in it's string form. But I have tried all the solutions but it won't compile on "Flat assembler". Following is my code :

I am trying to develop a small OS with custom bootloader. I have a little bit of experience in OSDEV but not that much... My problem is that the first stage bootloader does not load the seconds from the disk. this is the boot.asm file: