Mov ax 13h int 10h

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. With the above code when you press RightDOS first returns a zero in the AL register and expects you to issue another invocation of function 07h in order to receive the actual scancode which will be 4Dh or 77 in decimal.

Your use of reading port 60h could be considered that 2nd invocation but it will never return any keyboard release code like the b that you seem to expect. The BIOS. WaitKeystroke function in your second program will also never return keyboard release codes. For an example of using port 60h that might help you see Faster keyboard scan code detection in assembly. Learn more. Tasm Turbo Assembler Ask Question.

Asked 3 days ago. Active 2 days ago. Viewed 36 times. Gad Gad 17 2 2 bronze badges. Did you try single-stepping in a debugger and seeing what value you actually get in AL for that keypress?

If not, do that. Also, your branching is overcomplicated. Just put lbl2 in the same place as lop instead of jumping to another jmp. Lay out your branches so you don't need as many total, especially unconditional branches. Easier to follow in your head, and to debug. I tried to check in a debugger but I didn't I succeeded Do you have any idea to solve it? Double-check your definitions of RightUP and other constants that they match what you see in AL with a debugger.

Add info that you find with a debugger to your question. Is that the difference you were looking for. It's not even clear what you're saying is happening vs. See minimal reproducible example. Ok, I think I might understand what you're saying now.

I wonder if there's a key-release event in the keyboard buffer from letting go of the return key when your program starts? Could in be reading that?The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and floppy disk read and write services using cylinder-head-sector CHS addressing.

INT is an x86 instruction that triggers a software interruptand 13 hex is the interrupt number as a hexadecimal value being called. In DOS, it serves as the low-level interface for the built-in block device drivers for hard disks and floppy disks. Under protected mode operating systems, such as Microsoft Windows NT derivatives e. Windows 9x and Windows for Workgroups 3.

mov ax 13h int 10h

By the time the MB barrier was being approached, ATA disks had long before ceased to present their real physical geometry parameters at the external ATA interface. The MB limit originates from a combination of the register value based calling convention used in the INT 13h interface and the goal of maintaining backward compatibility—dictatng that the format or size of CHS addresses passed to INT 13h could not be changed to add more bits to one of the fields, e.

This limit uses cylinders, heads, 63 sectors, and byte blocks, allowing exactly 7. This is a "packet" interface, because it uses a pointer to a packet of information rather than the register based calling convention of the original INT 13h interface. This packet is a very simple data structure that contains an interface version, data size, and LBAs.

mov ax 13h int 10h

For software backward-compatibility, the extended functions are implemented alongside the original CHS functions, and calls to functions from both sets can be intermixed, even for the same drive, with the caveat that the CHS functions cannot reach past the first MB of the disk. Some cache drivers flush their buffers when detecting that DOS is bypassed by directly issuing INT 13h from applications.

A dummy read via INT 13h can be used as one of several methods to force cache flushing for unknown caches e. Register CX contains both the cylinder number 10 bitspossible values are 0 to and the sector number 6 bits, possible values are 1 to Cylinder and Sector bits are numbered below:.

mov ax 13h int 10h

Addressing of Buffer should guarantee that the complete buffer is inside the given segmenti. Otherwise the interrupt may fail with some BIOS or hardware versions. Utilizing memory segmentationthere are different ways to calculate the register values, e. Function 02h of interrupt 13h may only read sectors of the first 16, sectors of your hard drive, to read sectors beyond the 8 GB limit you should use function 42h of INT 13h Extensions.

Another alternate may be DOS interrupt 25h which reads sectors within a partition. The only difference between this function and function 02h see above is that function 0Ah reads bytes per sector instead of only From Wikipedia, the free encyclopedia.

This article needs additional citations for verification.

Navigation

Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Not to be confused with Mode 13h. Retrieved Hidden categories: Articles needing additional references from September All articles needing additional references Use dmy dates from May All articles with unsourced statements Articles with unsourced statements from October Namespaces Article Talk. Views Read Edit View history.

By using this site, you agree to the Terms of Use and Privacy Policy. ES:DI [7]. DH [7]. BL [7].We know that all your variables, and all the code that makes up your final program reside in memory. Variables usually in the Data Segment and code, suprisingly enough, in the Code Segment [btw - just like the register DS points to the Data segment, CS points to the code segment. But, let's not worry about that right now]. Well, there are other various specific segments of memory, though they don't have registers associated with them.

One of these segments of memory holds all the data for what's stored on the screen. Depening on whether you're using only text, or using graphics, the location may change around. For simplicity right now, we'll talk about text. Our last program printed text on the screen using an interrupt. In all our previous programs, we didn't specify what screen mode we wanted to use. So by default, it uses a text screen mode. This means that the screen is set up then so you can only put text onto it.

So how do we specify the screen mode? There's an interrupt that'll change the screen mode for us. Take a look at this program:. You may notice this is a bit different than how the previous programs used interrupts. Here, put a value only in ax. The change screen mode function is function 0 of interrupt So, to use it, we must put 0 in ah. And this function requires that you put the screen mode you want in al. Since ax consists of ah and al, i just moved a value straight into ax.

Now ah should contain 00, and al should contain Int 10h Don't Print With Colors. What I got is that normal gray, but why I'm getting this? What I need to do? Best Regards, Nathan Paulino Campos.

Foreground color in bl is for graphic modes only. For text modes, correct bh is much more significant. You can make "each character different" or "all characters what's in bl" and advance the cursor or not, depending on what's in al.

An "odd" interrupt, but powerful Best, Frank. It prints on the paper provided unless you're in graphic mode where you have to have at least foreground color. Straightforward, and faster, besides not that it matters - it'll print faster than we can read it in any case.

Have to do most of it anyway Ok, but being at text mode, what I can do? Without doing that strange, but useful use of the language that fbkotler said. As baldr points out, you're using the "teletype" interrupt. You're putting 0Fh in bl, which would give you "bright white", not "blue", anyway.

No ints! This is more complicated than it needs to be - I "rotate" the colors in a rather stupid way - but you can probably extract the "essence".

Look it up. The first one I understood very fast, because when I was designing my OS using C, I use that as a pointer to print things on the screen. Anyway, when I tried this now, my OS don't want to boot. Well, they won't run on Linux, either. As posted, they're intended to be. If they're preventing your OS from bootingThe BIOS typically sets up a real mode interrupt handler at this vector that provides video services.

Such services include setting the video mode, character and string output, and graphics primitives reading and writing pixels in graphics mode. To use this call, load AH with the number of the desired subfunction, load other required parameters in other registers, and make the call. Setting the video mode, which is done infrequently, can be accomplished by using the BIOS, while drawing graphics on the screen in a game needs to be done quickly, so direct access to video RAM is more appropriate than making a BIOS call for every pixel.

This means that a modern operating system, which operates in Protected mode 32 bitor Long mode 64 bitwould need to switch into real mode and back to call the BIOS - a hugely expensive operation. Although most modern systems typically use device drivers that directly set the video mode, it is not feasible for hobbyist systems to have a device driver for every video card - a problem that also plagues older, unsupported systems such as Windows Such systems instead can drop into Real mode to switch the video mode, then draw to the framebuffer directly.

Normally a character cell has 8 scan lines, If bit 5 of CH is set, that often means "Hide cursor". Refer the BIOS color attributes. From Wikipedia, the free encyclopedia.

This article includes a list of referencesbut its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. June Learn how and when to remove this template message. Forever Young Software. Retrieved March 8, Hidden categories: Articles lacking in-text citations from June All articles lacking in-text citations. Namespaces Article Talk.

Subscribe to RSS

Views Read Edit View history. By using this site, you agree to the Terms of Use and Privacy Policy. Some video cards have 16 scan lines, 00h-0Fh.

Thomas dieterich

Some video cards don't use bit 5 of CH. Read light pen position Does not work on VGA systems.

Subscribe to RSS

Change text mode character set [1].By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I used all the memory in the first sector, now I want to store a new variable string in the second sector second stage and print it.

For instance:. The new string should be in another sector because there is no more memory in the first sector. I stored the variable hello in that sector as well as the code to print.

When the variable is in the first sector it prints well, but when I store it in the second sector it doesn't print, even when I do:. Your code was correct in the very first snippet. I believe you should just remove the first appearance of the label in your code. All absolute memory references are relative to an offset of 0. In your case that is what you want for the first sector bytes of your assembler file. You have coded your bootloader to use a segment of 0x7c0the segment you choose and an origin point of 0 should point to a physical address of 7c00h.

So all is well and good, you properly read the sectors into memory at h:0h. This too is correct. If all this is correct where is the problem? The issue is that NASM has no idea you loaded the code after the first bytes to another location in memory and that the segment:offset used would be relative to 0 again hh. It will continue to generate absolute addresses relative to the beginning of your bootloader.

How to hide mouse cursor in bluestacks

The -e says to skip disassembling the first bytes of the file. I'm just interested in the first few lines of the output, in particular:. But notice that 0x21a is decimal and that would be the offset relative to the beginning of the entire bootloader not relative to an offset of 0 hh. To fix this, you need to instruct NASM that the code generated in the second stage second sector needs to be relative to an origin of 0 and not relative to the beginning of the bootloader.

This can easily be done by placing the second stage second sector in a new section where the origin point vstart is reset to 0. That can be done by placing a section directive like this at the beginning of the second stage:.

Jester was on the right track with org 0h being placed before the second stage code second sectorbut there can only be one ORG directive in each assembly file. No matter where you place it in the file, NASM will act as if it actually found it at the top of the file.

This behaviour is not well documented!By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

I used all the memory in the first sector, now I want to store a new variable string in the second sector second stage and print it. For instance:. The new string should be in another sector because there is no more memory in the first sector. I stored the variable hello in that sector as well as the code to print. When the variable is in the first sector it prints well, but when I store it in the second sector it doesn't print, even when I do:. Your code was correct in the very first snippet.

I believe you should just remove the first appearance of the label in your code. All absolute memory references are relative to an offset of 0. In your case that is what you want for the first sector bytes of your assembler file. You have coded your bootloader to use a segment of 0x7c0the segment you choose and an origin point of 0 should point to a physical address of 7c00h.

So all is well and good, you properly read the sectors into memory at h:0h. This too is correct. If all this is correct where is the problem? The issue is that NASM has no idea you loaded the code after the first bytes to another location in memory and that the segment:offset used would be relative to 0 again hh. It will continue to generate absolute addresses relative to the beginning of your bootloader.

The -e says to skip disassembling the first bytes of the file. I'm just interested in the first few lines of the output, in particular:. But notice that 0x21a is decimal and that would be the offset relative to the beginning of the entire bootloader not relative to an offset of 0 hh.

To fix this, you need to instruct NASM that the code generated in the second stage second sector needs to be relative to an origin of 0 and not relative to the beginning of the bootloader. This can easily be done by placing the second stage second sector in a new section where the origin point vstart is reset to 0. That can be done by placing a section directive like this at the beginning of the second stage:. Jester was on the right track with org 0h being placed before the second stage code second sectorbut there can only be one ORG directive in each assembly file.

No matter where you place it in the file, NASM will act as if it actually found it at the top of the file. This behaviour is not well documented! Jester's solution wouldn't have changed anything. Learn more. Asked 3 years, 9 months ago. Active 3 years, 9 months ago. Viewed 2k times.

Marathi old remix dj songs mp3 orignal voice

For instance: hello db 'Hello World' The new string should be in another sector because there is no more memory in the first sector. Michael Petch JesMot JesMot 43 4 4 bronze badges. What do you mean by "sector"? Are you talking about segments?

Red dead redemption 2 pc blurry fix

Or, since you are using int 13h, you probably mean sectors on a hard disk. In that case, you have to load the value from the disk by making a system call.


thoughts on “Mov ax 13h int 10h”

Leave a Reply

Your email address will not be published. Required fields are marked *