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How to w/r harddisk in pmode? https://forum.osdev.org/viewtopic.php?f=1&t=12268 |
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Author: | raywill [ Thu Nov 23, 2006 7:00 pm ] |
Post subject: | How to w/r harddisk in pmode? |
In real mode I can use int 13h to read harddisk.But in pmode,I can't use it any more,neither do I want to use it. I have noticed the code in Linux 0.01 , they use in,out command to read sectors. My question is : Without any initialization can I use in,out to access harddisk? Must I write PCI driver first ?Is it hard? Thanks~ Suppose I am using IDE diskdriver. |
Author: | Dex [ Thu Nov 23, 2006 9:52 pm ] |
Post subject: | Re: How to w/r harddisk in pmode? |
raywill wrote: In real mode I can use int 13h to read harddisk.But in pmode,I can't use it any more,neither do I want to use it. I have noticed the code in Linux 0.01 , they use in,out command to read sectors. My question is : Without any initialization can I use in,out to access harddisk? Must I write PCI driver first ?Is it hard? Thanks~ Suppose I am using IDE diskdriver. To read/write to hdd is very easy, but it's the fat that will take more time, to get right. Code: ; Reading the harddisk using ports! ; +-------------------------------+ by qark ; ; ; This took me months to get working but I finally managed it. ; ; This code only works for the 286+ so you must detect for 8088's somewhere ; in your code. ; ; Technical Information on the ports: ; Port Read/Write Misc ; ------ ------------ ------------------------------------------------- ; 1f0 r/w data register, the bytes are written/read here ; 1f1 r error register (look these values up yourself) ; 1f2 r/w sector count, how many sectors to read/write ; 1f3 r/w sector number, the actual sector wanted ; 1f4 r/w cylinder low, cylinders is 0-1024 ; 1f5 r/w cylinder high, this makes up the rest of the 1024 ; 1f6 r/w drive/head ; bit 7 = 1 ; bit 6 = 0 ; bit 5 = 1 ; bit 4 = 0 drive 0 select ; = 1 drive 1 select ; bit 3-0 head select bits ; 1f7 r status register ; bit 7 = 1 controller is executing a command ; bit 6 = 1 drive is ready ; bit 5 = 1 write fault ; bit 4 = 1 seek complete ; bit 3 = 1 sector buffer requires servicing ; bit 2 = 1 disk data read corrected ; bit 1 = 1 index - set to 1 each revolution ; bit 0 = 1 previous command ended in an error ; 1f7 w command register ; commands: ; 50h format track ; 20h read sectors with retry ; 21h read sectors without retry ; 22h read long with retry ; 23h read long without retry ; 30h write sectors with retry ; 31h write sectors without retry ; 32h write long with retry ; 33h write long without retry ; ; Most of these should work on even non-IDE hard disks. ; This code is for reading, the code for writing is the next article. mov dx,1f6h ;Drive and head port mov al,0a0h ;Drive 0, head 0 out dx,al mov dx,1f2h ;Sector count port mov al,1 ;Read one sector out dx,al mov dx,1f3h ;Sector number port mov al,1 ;Read sector one out dx,al mov dx,1f4h ;Cylinder low port mov al,0 ;Cylinder 0 out dx,al mov dx,1f5h ;Cylinder high port mov al,0 ;The rest of the cylinder 0 out dx,al mov dx,1f7h ;Command port mov al,20h ;Read with retry. out dx,al still_going: in al,dx test al,8 ;This means the sector buffer requires ;servicing. jz still_going ;Don't continue until the sector buffer ;is ready. mov cx,512/2 ;One sector /2 mov di,offset buffer mov dx,1f0h ;Data port - data comes in and out of here. rep insw ; ------ mov ax,201h ;Read using int13h then compare buffers. mov dx,80h mov cx,1 mov bx,offset buffer2 int 13h mov cx,512 mov si,offset buffer mov di,offset buffer2 repe cmpsb jne failure mov ah,9 mov dx,offset readmsg int 21h jmp good_exit failure: mov ah,9 mov dx,offset failmsg int 21h good_exit: mov ax,4c00h ;Exit the program int 21h readmsg db 'The buffers match. Hard disk read using ports.$' failmsg db 'The buffers do not match.$' buffer db 512 dup ('V') buffer2 db 512 dup ('L') ; ; Writing to the hard disk using the ports! by qark ; +---------------------------------------+ ; ; The only differences between reading and writing using the ports is ; that 30h is sent to the command register, and instead of INSW you ; OUTSW. ; mov dx,1f6h ;Drive and head port mov al,0a0h ;Drive 0, head 0 out dx,al mov dx,1f2h ;Sector count port mov al,1 ;Write one sector out dx,al mov dx,1f3h ;Sector number port mov al,1 ;Wrote to sector one out dx,al mov dx,1f4h ;Cylinder low port mov al,0 ;Cylinder 0 out dx,al mov dx,1f5h ;Cylinder high port mov al,0 ;The rest of the cylinder 0 out dx,al mov dx,1f7h ;Command port mov al,30h ;Write with retry. out dx,al oogle: in al,dx test al,8 ;Wait for sector buffer ready. jz oogle mov cx,512/2 ;One sector /2 mov si,offset buffer mov dx,1f0h ;Data port - data comes in and out of here. rep outsw ;Send it. ; ------------ mov ax,201h ;We'll read in sector 1 using mov bx,offset buffer2 ;int13h and see if we are successful. mov cx,1 mov dx,80h int 13h mov cx,512 mov si,offset buffer mov di,offset buffer2 repe cmpsb ;Compare the buffers. jne failure mov ah,9 mov dx,offset write_msg int 21h jmp w_exit failure: mov ah,9 mov dx,offset fail int 21h w_exit: mov ax,4c00h ;Exit the program int 21h write_msg db 'Sector one written to using the ports, OH NO! there goes XP.$' fail db 'Writing using ports failed.$' buffer db 512 dup ('A') buffer2 db 512 dup ('D') NOTE: THE ABOVE CODE WILL OVER WRITE YOUR MBR, so do not run with above settings. |
Author: | carbonBased [ Thu Nov 23, 2006 10:00 pm ] |
Post subject: | |
Also note that (I believe) most/all modern HD drivers utilize DMA, rather then direct port IO. I have yet to write an HD driver for ndk, though, so I have no insight on how this is done. --Jeff |
Author: | raywill [ Thu Nov 23, 2006 10:47 pm ] |
Post subject: | Re: How to w/r harddisk in pmode? |
So,according to the code,I don't need to init PCI first?Why? Then another question is : HOW does the computer do this? Who have helped us to map those I/O port? Lots thanks,Dex! Dex wrote: raywill wrote: In real mode I can use int 13h to read harddisk.But in pmode,I can't use it any more,neither do I want to use it. I have noticed the code in Linux 0.01 , they use in,out command to read sectors. My question is : Without any initialization can I use in,out to access harddisk? Must I write PCI driver first ?Is it hard? Thanks~ Suppose I am using IDE diskdriver. To read/write to hdd is very easy, but it's the fat that will take more time, to get right. Code: ; Reading the harddisk using ports! ; +-------------------------------+ by qark ; ; ; This took me months to get working but I finally managed it. ; ; This code only works for the 286+ so you must detect for 8088's somewhere ; in your code. ; ; Technical Information on the ports: ; Port Read/Write Misc ; ------ ------------ ------------------------------------------------- ; 1f0 r/w data register, the bytes are written/read here ; 1f1 r error register (look these values up yourself) ; 1f2 r/w sector count, how many sectors to read/write ; 1f3 r/w sector number, the actual sector wanted ; 1f4 r/w cylinder low, cylinders is 0-1024 ; 1f5 r/w cylinder high, this makes up the rest of the 1024 ; 1f6 r/w drive/head ; bit 7 = 1 ; bit 6 = 0 ; bit 5 = 1 ; bit 4 = 0 drive 0 select ; = 1 drive 1 select ; bit 3-0 head select bits ; 1f7 r status register ; bit 7 = 1 controller is executing a command ; bit 6 = 1 drive is ready ; bit 5 = 1 write fault ; bit 4 = 1 seek complete ; bit 3 = 1 sector buffer requires servicing ; bit 2 = 1 disk data read corrected ; bit 1 = 1 index - set to 1 each revolution ; bit 0 = 1 previous command ended in an error ; 1f7 w command register ; commands: ; 50h format track ; 20h read sectors with retry ; 21h read sectors without retry ; 22h read long with retry ; 23h read long without retry ; 30h write sectors with retry ; 31h write sectors without retry ; 32h write long with retry ; 33h write long without retry ; ; Most of these should work on even non-IDE hard disks. ; This code is for reading, the code for writing is the next article. mov dx,1f6h ;Drive and head port mov al,0a0h ;Drive 0, head 0 out dx,al mov dx,1f2h ;Sector count port mov al,1 ;Read one sector out dx,al mov dx,1f3h ;Sector number port mov al,1 ;Read sector one out dx,al ... NOTE: THE ABOVE CODE WILL OVER WRITE YOUR MBR, so do not run with above settings. |
Author: | Brendan [ Thu Nov 23, 2006 11:48 pm ] |
Post subject: | Re: How to w/r harddisk in pmode? |
Hi, raywill wrote: So,according to the code,I don't need to init PCI first?Why?
For backwards compatibility purposes, the ATA/IDE controller is pre-configured by the BIOS to look and behave like a standard ISA ATA/IDE controller. Also note that due to a series of brain-dead hardware designers (who assume that if a design is good enough for the next 5 minutes it will be good enough for the next 10 years), there's several different ways of transferring data to/from the disks, and several different ways of telling the disk which sector/s you want to access, most of which may or may not be supported by the hardware itself. This is a little worse because the controller and the disk drives are seperate - a disk can support features that the controller doesn't support, and a controller can support features that the disk/s don't. This means to support the fastest possible disk transfer speed and all possible disk sizes you need to detect what the disk and controller support and implement code for each possibility. It's also probable worth looking through the public domain code written by Hale Landis (available from this web site). This code doesn't support some advanced features (SMART, NCQ, drive locking, etc), but these things are easy to live without.... Cheers, Brendan |
Author: | kataklinger [ Fri Nov 24, 2006 2:33 pm ] |
Post subject: | |
Well, you must write PCI detection driver if you want to have more ATA/ATAPI controllers or to use UltraDMA. I suggest you to visit www.ata-atapi.com . There's a very nice source code for PATA/PATAPI/SATA/SATAPI with support for UltraDMA device driver! |
Author: | nicola [ Sun May 22, 2011 3:44 am ] |
Post subject: | Re: How to w/r harddisk in pmode? |
great and neat code, Dex, but is it possible to read/write more than 255 sectors? as i see in your code AL is a byte value: Code: mov dx,1f2h ;Sector count port
mov al,1 ;Read one sector out dx,al |
Author: | quok [ Sun May 22, 2011 8:54 am ] |
Post subject: | Re: How to w/r harddisk in pmode? |
Did you really need to bump a 5 year old thread? To answer your question, try reading the specs. They're easy to find and explain everything you need to know. It's about time you do your own homework for once. |
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