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> OS Construction > Trying to turn on leds in windows or real mode(at bootstrap) |
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MarcoAlves 21 Jun 2006, 14:27
Hi all.
I'd read a lot of about 8042 microcontroller. This because I'm making my own bootloader and I need understand on how to enable a20 gate. But, before I try to enable the a20 gate, I'm trying something more simple, IMHO, i.e., trying to turn on all led indicators. But I have few questions: Is the 8042 INSIDE the keyboard case? When I make a comand to 60h, the command is received by 8042? When I make a command to 64h, the command is received by motherboard onboard microcontroller? reference: http://www.arl.wustl.edu/~lockwood/class/cs306/books/artofasm/Chapter_20/CH20-1.html#HEADING1-5 Also, the following code is my attempt to turn on leds in windows or real mode (in my bootloader). It doesn't works. Can someone help me? In the case of testing the code in my boot loader, I just include the code via inc directive after my "Hello Word" message. I already read other articles in the forum about enable keyboard leds and already try them, but without success. note: I have a notebook. But I think that this does not change anything. Ah, a last question: How I can do something like this in fasm: KB_ALL_LEDS equ KB_CAPS_LOCK | KB_NUM_LOCK | KB_SCROLL_LOCK Code: ; Turn on all leds of the keyboard. ORG 0x100 ; Remove it in case of it is placed in bootloader. turnOnLeds: ;This subroutine will turn on led indicators in the keyboard controller. ;Takes no arguments. Returns 0 in AX register on success, -1 on failure. ;Written for use in 16-bit code. ; Status Register STATUS_PORT equ 0x64 KBD_OUT_BUF equ 0x60 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Symbolic constants definition ; Status Register Bits Names SR_BIT0_OUTPUT_BUFFER equ 0 ; 0->has no data for system; 1->has data for system SR_BIT1_INPUT_BUFFER equ 1 ; 0->has no data for 8042; 1-> has data for 8042 SR_BIT2_SYSTEM_FLAG equ 2 ; system flag (set to 0 after power on reset) SR_BIT3_COMMAND_DATA equ 3 ; type of information in input register. 1->command; 0->data SR_BIT4_ENABLED_DISABLED equ 4 ; 1->keyboard enabled; 2-> keyboard disabled (via switch) SR_BIT5_TRANSMIT_TIMEOUT equ 5 ; 1->transmit timeout SR_BIT6_RECEIVE_TIMEOUT equ 6 ; 1-> receive timeout SR_BIT7_PARITY equ 7 ; 1-> even parity; 0->odd parity ; Keyboard Commands KB_LED_CMD equ 0xED ; Keyboard Led Indicators KB_CAPS_LOCK equ 001b KB_NUM_LOCK equ 010b KB_SCROLL_LOCK equ 101b ;KB_ALL_LEDS equ KB_CAPS_LOCK | KB_NUM_LOCK | KB_SCROLL_LOCK KB_ALL_LEDS equ 111b ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; pusha ; Pushes the contents of the general-purpuse registers ; onto the stack following order: AX, CX, DX, BX, BP, SP ; (original value), BP, SI and DI. The value pushed for ; the SP register is its value before prior to pushing ; the first register. cli ; Disable interrupts ; Wait for the keyboard controller to be ready for a command xor ax,ax ; Clear ax .commandWait1: in al,STATUS_PORT ; Reads the 8042 status register bt ax,SR_BIT1_INPUT_BUFFER ; Test if command buffer is full jc .commandWait1 ; Input buffer is full. Try again. mov al,KB_LED_CMD ; Tell 8042 we wanna change the LEDs out KBD_OUT_BUF,al ; Send the command .wait: xor ax,ax in al,STATUS_PORT bt ax,SR_BIT1_INPUT_BUFFER ; Test if command came through jc .wait xor ax,ax mov al,KB_ALL_LEDS ; Tell 8042 the option byte out KBD_OUT_BUF,al ; Set all LED's to ON sti ; Re-enable interrupts popa ; Pops words from the stack into the general-purpose ; registers. The registers are loaded in the following ; order: DI, SI, BP, BX, DX, CX and AX. The value on ; the stack for the SP register is ignored. Instead, ; the SP register is incremented after each register ; is loaded. ret ;------------------------------------------------------------; ; keyboard wait ; ; Wait for the keyboard controller to be ready for a command ; ;------------------------------------------------------------; ;.kbd_wait: ;jmp $+2 ;in al,STATUS_PORT ;test al,1 ;jz .ok ;jmp $+2 ;in al,KBD_OUT_BUF ;jmp .kbd_wait ;.ok: ;test al,2 ;jnz .kbd_wait ;ret Thx in advance. Best regards, Marco Alves. |
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21 Jun 2006, 14:27 |
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Dex4u 21 Jun 2006, 15:15
This is my function fot turn leds on/off
Code: ;====================================================;; Set keyboard leds ;;====================================================;SetKeyBoardLeds: push eax mov al,0xed out 60h,alKeyBoardWait: in al,64h test al,10b jne KeyBoardWait mov al,byte [keyBoardStatus] ;put 7 in this var and al,111b out 60h,al pop eax ret Note: if your talking XP, then alot of direct hardware stuff does not work, should be ok in win98 or boot code. PS: bubach site is a goldmine of doc and code snips, on all OS topics including keyboards http://bos.asmhackers.net/docs/keyboard/ |
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21 Jun 2006, 15:15 |
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Dex4u 21 Jun 2006, 16:35
I have tested the code and this is the fixed ver
Code: include 'include/boot_image.asm'Boot_Sector:use16 ; We need 16-bit intructions for Real ModeORG 0x7C00 ; The BIOS loads the boot sector into this memory location; Main programmain:mov ax,0x0000 ; Setup the Data Segment register ; Location of data in DS:Offsetmov ds,ax ; This can not be loaded directly. Is has to be in two steps. ; "mov ds,0x0000" will NOT work due to limitations on CPU.mov si,HelloWorld ; Load the string into position for the procedure.call PutStr ; Run the proceduremov [keyBoardStatus],7 ;***** you did not put 7 in var *****call SetKeyBoardLedsjmp $ ;***** you did not put this to stop the codekeyBoardStatus db 0 ;**** you put this in the wrong place.;====================================================;; Set keyboard leds ;;====================================================;SetKeyBoardLeds: push ax mov al,0xed out 60h,alKeyBoardWait: in al,64h test al,10b jne KeyBoardWait mov al,byte [keyBoardStatus] ;put 7 in this var and al,111b out 60h,al pop ax ret;ProceduresPutStr: ; Set up the register for the interrupt callmov ah,0x0E ; The function to display a charactermov bh,0x00 ; Page numbermov bl,0x07 ; Normal attribute;****************************************************************************************nextchar: ; Internal label (needed to loop round for the next character)lodsb ; I think of this as LOaD String Block;Check for end of string '0'. The or instruction in this context is just to;put 0 or 1 on ZF (zero flag). If is the end of string, put 1, 0 otherwise.or al,aljz return ; If the zero flag has been set go to the end of the procedure. ; Zero flag gets set when an instruction returns 0 as the answer.int 10h ; Run the BIOS video interruptjmp nextchar ; Loop back round to the top;****************************************************************************************;****************************************************************************************return: ; Label at the end to jump when completeret ; Return to main program;****************************************************************************************; DataHelloWorld db 'Hello World',13,10,0; End mattertimes 510-($-$$) db 0 ; Boot loader MUST have 512 bytes long.dw 0xAA55 Note the fixed ver works on my PC, i taken out the boot_image.asm as i did not have it when testing and i used rawrite to put it on disk. The led function worked fine. |
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21 Jun 2006, 16:35 |
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MarcoAlves 21 Jun 2006, 17:36
It didn't work for me. I don't know what's happening.
The boot_image.asm is attached, so you can test with it. Just put it on top of your code and assemble it. No need to use rawwrite. Ah, how I can put my boot.bin into a floppy image using rawwrite? Thx in advance. Best regards, Marco Alves.
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21 Jun 2006, 17:36 |
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Dex4u 21 Jun 2006, 18:15
That code is for cd i have no CD-R/RW to test, but my code above is tested on floppy and works on 10 test PC.
I made you a floppy image of my code, if you have burn software click on the make bootable and point it to that image. as for rawrite (included) just click on it and follow whats on screen, but needs a floppy drive.
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21 Jun 2006, 18:15 |
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MarcoAlves 22 Jun 2006, 12:29
Dex4u, I get it!
boot.asm: Code: ;include 'include/boot_image.asm' use16 ; We need 16-bit intructions for Real Mode ORG 0x7C00 ; The BIOS loads the boot sector into this memory location Boot_Sector: jmp near main nop ;------------------------------------------; ; Standard BIOS Parameter Block, "BPB". ; ;------------------------------------------; bpbOEM db 'BOS 0.04' bpbSectSize dw 512 bpbClustSize db 1 bpbReservedSec dw 1 bpbFats db 2 bpbRootSize dw 224 bpbTotalSect dw 2880 bpbMedia db 240 bpbFatSize dw 9 bpbTrackSect dw 18 bpbHeads dw 2 bpbHiddenSect dd 0 bpbLargeSect dd 0 ;---------------------------------; ; extended BPB for FAT12/FAT16 ; ;---------------------------------; bpbDriveNo db 0 bpbReserved db 0 bpbSignature db 41 ; 0 = nothing more. 41 = three more (below).. bpbID dd 1 bpbVolumeLabel db 'BOOT FLOPPY' bpbFileSystem db 'FAT12 ' ; Main program main: mov ax,0x0000 ; Setup the Data Segment register ; Location of data in DS:Offset mov ds,ax ; This can not be loaded directly. Is has to be in two steps. ; "mov ds,0x0000" will NOT work due to limitations on CPU. mov si,HelloWorld ; Load the string into position for the procedure. call PutStr ; Run the procedure call TurnOnLeds include 'KeyBoard/TurnOnLeds.asm' jmp $ ; Never ending loop ;Procedures PutStr: ; Set up the register for the interrupt call mov ah,0x0E ; The function to display a character mov bh,0x00 ; Page number mov bl,0x07 ; Normal attribute ;**************************************************************************************** nextchar: ; Internal label (needed to loop round for the next character) lodsb ; I think of this as LOaD String Block ;Check for end of string '0'. The or instruction in this context is just to ;put 0 or 1 on ZF (zero flag). If is the end of string, put 1, 0 otherwise. or al,al jz return ; If the zero flag has been set go to the end of the procedure. ; Zero flag gets set when an instruction returns 0 as the answer. int 10h ; Run the BIOS video interrupt jmp nextchar ; Loop back round to the top ;**************************************************************************************** ;**************************************************************************************** return: ; Label at the end to jump when complete ret ; Return to main program ;**************************************************************************************** ; Data HelloWorld db 'Hello World',13,10,0 ; End matter times 510-($-$$) db 0 ; Boot loader MUST have 512 bytes long. dw 0xAA55 TurnOnLeds.asm: Code: ; Turn on all leds of the keyboard. TurnOnLeds: ;This subroutine will turn on led indicators in the keyboard controller. ;Takes no arguments. ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; 8042 Definitions ; Status Register STATUS_PORT equ 0x64 KBD_OUT_BUF equ 0x60 ; Status Register Bits Names SR_BIT0_OUTPUT_BUFFER equ 0 ; 0->has no data for system; 1->has data for system SR_BIT1_INPUT_BUFFER equ 1 ; 0->has no data for 8042; 1-> has data for 8042 SR_BIT2_SYSTEM_FLAG equ 2 ; system flag (set to 0 after power on reset) SR_BIT3_COMMAND_DATA equ 3 ; type of information in input register. 1->command; 0->data SR_BIT4_ENABLED_DISABLED equ 4 ; 1->keyboard enabled; 2-> keyboard disabled (via switch) SR_BIT5_TRANSMIT_TIMEOUT equ 5 ; 1->transmit timeout SR_BIT6_RECEIVE_TIMEOUT equ 6 ; 1-> receive timeout SR_BIT7_PARITY equ 7 ; 1-> even parity; 0->odd parity ; Keyboard Commands KB_LED_CMD equ 0xED ; Keyboard Led Indicators KB_CAPS_LOCK equ 001b KB_NUM_LOCK equ 010b KB_SCROLL_LOCK equ 101b ;KB_ALL_LEDS equ KB_CAPS_LOCK | KB_NUM_LOCK | KB_SCROLL_LOCK KB_ALL_LEDS equ 111b ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; pusha ; Pushes the contents of the general-purpuse registers ; onto the stack following order: AX, CX, DX, BX, BP, SP ; (original value), BP, SI and DI. The value pushed for ; the SP register is its value before prior to pushing ; the first register. cli ; Disable interrupts xor ax,ax ; Clear ax call .kbd_wait ; Wait for the keyboard controller to be ready for a command mov al,KB_LED_CMD ; Tell 8042 we wanna change the LEDs out KBD_OUT_BUF,al ; Send the command xor ax,ax call .kbd_wait xor ax,ax mov al,KB_ALL_LEDS ; Tell 8042 the option byte out KBD_OUT_BUF,al ; Set all LED's to ON sti ; Re-enable interrupts popa ; Pops words from the stack into the general-purpose ; registers. The registers are loaded in the following ; order: DI, SI, BP, BX, DX, CX and AX. The value on ; the stack for the SP register is ignored. Instead, ; the SP register is incremented after each register ; is loaded. ret ;------------------------------------------------------------; ; keyboard wait ; ; Wait for the keyboard controller to be ready for a command ; ;------------------------------------------------------------; .kbd_wait: in al,STATUS_PORT ; Reads the 8042 status register bt ax,SR_BIT1_INPUT_BUFFER ; Test if command buffer is full jc .kbd_wait ; Input buffer is full. Try again. ret |
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22 Jun 2006, 12:29 |
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Dex4u 22 Jun 2006, 15:33
One thing you do, that you should watch, is put stuff in the functions, that should be put separated eg: this would be better.
Code: ; Turn on all leds of the keyboard.;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 8042 Definitions; Status RegisterSTATUS_PORT equ 0x64KBD_OUT_BUF equ 0x60; Status Register Bits NamesSR_BIT0_OUTPUT_BUFFER equ 0 ; 0->has no data for system; 1->has data for systemSR_BIT1_INPUT_BUFFER equ 1 ; 0->has no data for 8042; 1-> has data for 8042SR_BIT2_SYSTEM_FLAG equ 2 ; system flag (set to 0 after power on reset)SR_BIT3_COMMAND_DATA equ 3 ; type of information in input register. 1->command; 0->dataSR_BIT4_ENABLED_DISABLED equ 4 ; 1->keyboard enabled; 2-> keyboard disabled (via switch)SR_BIT5_TRANSMIT_TIMEOUT equ 5 ; 1->transmit timeoutSR_BIT6_RECEIVE_TIMEOUT equ 6 ; 1-> receive timeoutSR_BIT7_PARITY equ 7 ; 1-> even parity; 0->odd parity; Keyboard CommandsKB_LED_CMD equ 0xED; Keyboard Led IndicatorsKB_CAPS_LOCK equ 001bKB_NUM_LOCK equ 010bKB_SCROLL_LOCK equ 101b;KB_ALL_LEDS equ KB_CAPS_LOCK | KB_NUM_LOCK | KB_SCROLL_LOCKKB_ALL_LEDS equ 111b;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;TurnOnLeds: ;This subroutine will turn on led indicators in the keyboard controller. ;Takes no arguments.pusha ; Pushes the contents of the general-purpuse registers ; onto the stack following order: AX, CX, DX, BX, BP, SP ; (original value), BP, SI and DI. The value pushed for ; the SP register is its value before prior to pushing ; the first register.cli ; Disable interruptsxor ax,ax ; Clear axcall .kbd_wait ; Wait for the keyboard controller to be ready for a commandmov al,KB_LED_CMD ; Tell 8042 we wanna change the LEDsout KBD_OUT_BUF,al ; Send the commandxor ax,axcall .kbd_waitxor ax,axmov al,KB_ALL_LEDS ; Tell 8042 the option byteout KBD_OUT_BUF,al ; Set all LED's to ONsti ; Re-enable interruptspopa ; Pops words from the stack into the general-purpose ; registers. The registers are loaded in the following ; order: DI, SI, BP, BX, DX, CX and AX. The value on ; the stack for the SP register is ignored. Instead, ; the SP register is incremented after each register ; is loaded.ret;------------------------------------------------------------;; keyboard wait ;; Wait for the keyboard controller to be ready for a command ;;------------------------------------------------------------;.kbd_wait:in al,STATUS_PORT ; Reads the 8042 status registerbt ax,SR_BIT1_INPUT_BUFFER ; Test if command buffer is fulljc .kbd_wait ; Input buffer is full. Try again.ret |
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22 Jun 2006, 15:33 |
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MarcoAlves 22 Jun 2006, 16:55
Ah, ok. thx a lot. I'm very happy. It's my first own asm code. hehe
 .
Ah, just more one question: How I can do something like this: Code: KB_ALL_LEDS equ KB_CAPS_LOCK | KB_NUM_LOCK | KB_SCROLL_LOCK thx in advance. Marco Alves. |
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22 Jun 2006, 16:55 |
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Dex4u 22 Jun 2006, 17:47
Well done
, try this:
Code: ; Keyboard Led IndicatorsKB_CAPS_LOCK equ 00000001bKB_NUM_LOCK equ 00000010bKB_SCROLL_LOCK equ 00000101bKB_ALL_LEDS equ KB_CAPS_LOCK or KB_NUM_LOCK or KB_SCROLL_LOCK |
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22 Jun 2006, 17:47 |
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MarcoAlves 23 Jun 2006, 12:23
It works fine. Hey, can I add you to my msn?
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23 Jun 2006, 12:23 |
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Dex4u 23 Jun 2006, 13:52
You could if i used it
 , you may find members of 'Dex4u team' on IRC here:
http://jas2o.forthworks.com/?p=dex4u But i do not go on much. |
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23 Jun 2006, 13:52 |
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MarcoAlves 23 Jun 2006, 14:23
Ah. I made a A20 gate enabler.
It works fine in my notebook. I can't believe! hee. In last month I do not know anything about asm nor computer architecture (a20 gate? what's that?) hehe. And today I have a a20 gate write by my own. It's incredible! All was written by me! uhauha A20 gate enabler: Code: include 'Keyboard/Keyboard.asm' KB_A20_GATE equ 00000010b enableA20: ;Enables A20 gate. ;The main steps to enable A20 gate follows: ;1-Push all registers onto stack (pusha) ;2-Disable interrupts (cli) ;3-Verify if the keyboard is ready to receive a command (through 64h. bit 1 of status register must be 0) ;4-Read output port (D0 command via 64h. ;Wen we do this, the controller will read its output port and ;place the data in its output buffer) ;5-Wait for the controller to be ready with a byte of data (through 64h. bit 0 of status register must be 1) ;6-Read 8042 output buffer (considering the context, will be the 8042 output port) ;7-Or"s" this value with 00000010b (the 2nd bit is the A20 gate) ;8-Verify if the keyboard is ready to receive a command (see step 3) ;9-Tell 8042 we wanna enable A20 (D1 command via 64h) ;10-Wait for the controller to be ready for the data we going to send (bit 1 of status register must be 0) ;11-Send the value obtained in step 7 to 8042 output port (through 60h) ;The normal behavior implies that at this point the A20 gate will be already enabled. ;So we'll check if this is true. ;12-Verify if the keyboard is ready to receive a command (see step 3) ;13-Read output port (see step 4) ;14-Wait for the controller to be ready with a byte of data (see step 5) ;15-Read 8042 output buffer (see step 6) ;16-Use bt instruction to verify if bit 1 of output port is enabled. (if CF equals 1 it's enabled) ;17-push all registers from stack ;18-Re-enable interrputs ;19-Store 1 in al if success. Otherwise, 0. popa ; Step 1 cli ; Step 2 mov cx,5 ; Number of tries. .startIt: call .kbd_wait ; Step 3 mov al,KB_READ_OUTPUT_PORT ; Step 4 out STATUS_PORT,al call .kbd_output_buffer_empty ; Step 5 in al,KBD_OUT_BUF ; Step 6 or al,KB_A20_GATE ; Step 7 push ax call .kbd_wait ; Step 8 mov al,KB_WRITE_OUTPUT_PORT ; Step 9 out STATUS_PORT,al call .kbd_input_buffer_full ; Step 10 pop ax ; Step 11 out KBD_OUT_BUF,al ; If all occurs fine, the A20 gate will be enabled at this point. Checking it. call .kbd_wait ; Step 12 mov al,KB_READ_OUTPUT_PORT ; Step 13 out STATUS_PORT,al call .kbd_output_buffer_empty ; Step 14 in al,KBD_OUT_BUF ; Step 15 bt ax,1 ; Step 16 jc .success ret loop .startIt jmp .fail ret ;------------------------------------------------------------; ; A20 is enabled. Great job! ; ;------------------------------------------------------------; .success: sti ; Step 17 pusha ; Step 18 xor eax,eax mov al,1 ; Step 19 ret ;------------------------------------------------------------; ; A20 isn't enabled. Panic!? ; ;------------------------------------------------------------; .fail: sti ; Step 17 pusha ; Step 18 xor eax,eax mov al,0 ; Step 19 ret ;------------------------------------------------------------; ; keyboard wait ; ; Wait for the keyboard controller to be ready for a command ; ;------------------------------------------------------------; .kbd_wait: xor ax,ax in al,STATUS_PORT ; Reads the 8042 status register bt ax,SR_BIT1_INPUT_BUFFER ; Test if command buffer is full jc .kbd_wait ; Input buffer is full. Try again. ret ;------------------------------------------------------------; ; loop while keyboard input output buffer is empty ; ;------------------------------------------------------------; .kbd_output_buffer_empty: xor ax,ax in al,STATUS_PORT bt ax,SR_BIT0_OUTPUT_BUFFER jnc .kbd_input_buffer_empty ret ;------------------------------------------------------------; ; loop while keyboard output buffer is full ; ;------------------------------------------------------------; .kbd_output_buffer_full: xor ax,ax in al,STATUS_PORT bt ax,SR_BIT0_OUTPUT_BUFFER jc .kbd_input_buffer_full ret ;------------------------------------------------------------; ; loop while keyboard buffer is empty ; ;------------------------------------------------------------; .kbd_input_buffer_empty: xor ax,ax in al,STATUS_PORT bt ax,SR_BIT1_INPUT_BUFFER jnc .kbd_input_buffer_empty ret ;------------------------------------------------------------; ; loop while keyboard input buffer is full ; ;------------------------------------------------------------; .kbd_input_buffer_full: xor ax,ax in al,STATUS_PORT bt ax,SR_BIT1_INPUT_BUFFER jc .kbd_input_buffer_full ret |
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23 Jun 2006, 14:23 |
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Dex4u 23 Jun 2006, 15:01
Great
, but maybe you should check you may have done typo error popa (maybe should be pusha, and pusha (maybe should be popa) ?.
And maybe you should not have a 'ret' here: Code: jc .successret ;<******* This would mean you will not get a panic PS: Your a fast learner. |
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23 Jun 2006, 15:01 |
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MarcoAlves 23 Jun 2006, 19:52
my english is very poor. argh! I dont know if I must use "I'd use" or "I'd used" to put the phrase in the past. argh. sorry. i'm from brazil. I learn english by myself. no teacher. no class.
ok. I'd used pusha to put registers into memory. And, after the execution, restore original registers values. Just it. Nothing else. So, about ret after .success, thx. You're right. Thx But, one question: Code: jc .success .success: sti ; Step 17 pusha ; Step 18 xor eax,eax mov al,1 ; Step 19 ret When I do ret in .success it will return to the line after jc .success? |
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23 Jun 2006, 19:52 |
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Dex4u 23 Jun 2006, 23:34
Thats OK your English is good, but the ret will return you to the next instruction after the call, in your case after the:
Code: call enableA20; it will return here You do not ret, from a jump As for pusha, if you look at your code, it is popa first, it should be pusha first, You did this Code: popa ; Step 1 And at end you did this Code: pusha ; Step 18 You first push general reg's on stack with pusha, then you pop them off again with popa. |
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23 Jun 2006, 23:34 |
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MarcoAlves 26 Jun 2006, 15:14
Ok. I get it. thx.
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26 Jun 2006, 15:14 |
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