Now A20 line works

diff --git a/Boot486/boot0.S b/Boot486/boot0.S
index 21608cbc66d797064902c57826ca8fb215702b46..9ff81fabebf11bf2e9238c4cedc89178d7359357 100644 (file)
--- a/Boot486/boot0.S
+++ b/Boot486/boot0.S
@@ -25,8 +25,9 @@
 # Stage 1
 # =========================================================================== #
 
-.code16
 _start:
+
+.code16
 stage1:
 # 1. Setup canonical %cs:%eip, segment registers %ds, %es, %fs, %gs, %ss and stack %sp
        cli
@@ -41,10 +42,10 @@ stage1:
 
        mov %dx, BootDiskAdr
        call mapmem
+       sti
 
 # 2. Enable A20 gate
-       call enable_A20
-       sti
+       call enableA20
 
 # 3. Reset disk controller (%dl and %dh initialized by bios) and read Kernel into buffer
        movl $(kernel_code_end - kernel_code_start), KernelSizeAdr
@@ -263,161 +264,39 @@ readsectors__success:
        ret
 
 # =========================================================================== #
-# Check that A20 Gate is enabled
-#   output: set zero flag if disabled
-#   restore: %ds %es
+# Enable A20 Line
 # =========================================================================== #
 
 .code16
-check_A20:
-       push %ds
-       push %es
-#      push %ax
-#      push %di
-#      push %si
-
-       xor %ax, %ax
-       mov %ax, %es
-
-       not %ax
-       mov %ax, %ds
-
-       mov $0x0500, %di
-       mov $0x0510, %si
-
-       mov %es:0(%di), %al
-       push %ax
-
-       mov %ds:0(%si), %al
-       push %ax
-
-       movb $0x00, %es:0(%di)
-       movb $0xff, %ds:0(%si)
-
-       cmpb $0xff, %es:0(%di)
-
-       pop %ax
-       mov %es:0(%di), %al
-
-       pop %ax
-       mov %es:0(%di), %al
-
-       mov $0, %ax
-
-       je check_A20__exit
-
-       mov $1, %ax
-
-check_A20__exit:
-#      pop %si
-#      pop %di
-#      pop %ax
-       pop %es
-       pop %ds
-       or %al, %al
-       ret
-
-# =========================================================================== #
-# Enable A20 Gate
-# =========================================================================== #
-
-enable_A20:
-       /* First check */
-       call check_A20
-       jnz enable_A20__success
 
-       /* BIOS method */
-       mov $0x2401, %ax
-       int $0x15
-
-       call check_A20
-       jnz enable_A20__success
-
-       /* Keyboard method 1 */
-       mov $0xd0, %al
-       out %al, $0x64
-
-       call check_A20
-       jnz enable_A20__success
-
-       /* Keyboard method 2 */
-/*
-#      cli
-       
-       call enable_A20__wait1
-       mov $0xad, %al
-       out %al, $0x64
-
-       call enable_A20__wait1
-       mov $0xd0, %al
-       out %al, $0x64
-
-       enable_A20__wait2:
+enableA20:
+       cli
+       xor %cx, %cx
+enableA20_1:
+       inc %cx
+       jz enableA20_3
        in $0x64, %al
-       test $1, %al
-       jz enable_A20__wait2
-
-       in $0x60, %al
-       push %eax
-
-       call enable_A20__wait1
+       test $0x2, %al
+       jnz enableA20_1
        mov $0xd1, %al
        out %al, $0x64
-
-       call enable_A20__wait1
-       pop %eax
-       or $2, %al
-       out %al, $0x64
-
-       call enable_A20__wait1
-       mov $0xae, %al
-       out %al, $0x64
-
-       call enable_A20__wait1
-#      sti
-
-#      call check_A20
-#      jnz enable_A20__success
-*/
-
-       /* Control port A method */
-       mov $1, %al
-       out %al, $0x92
-
-       call check_A20
-       jnz enable_A20__success
-
-       /* Fast method */
-       in $0xee, %al
-
-       call check_A20
-       jnz enable_A20__success
-
-       mov $msg_a20_failed, %si
-       call print
-#      cli
-#      hlt
-
-enable_A20__success:
-       ret
-
-/*
-enable_A20__wait1:
+enableA20_2:
        in $0x64, %al
-       test $2, %al
-       jnz enable_A20__wait1
+       test $0x2, %al
+       jnz enableA20_2
+       mov $0xdf, %al
+       out %al, $0x60
+enableA20_3:
+       sti
        ret
-*/
 
 # =========================================================================== #
 # =========================================================================== #
 # =========================================================================== #
 
 msg_mapmem_failed: .asciz "1"
-msg_a20_failed: .asciz "2"
 msg_chs_error: .asciz "3"
 msg_kernel_read_failed: .asciz "4"
-
 msg_protected_mode: .asciz ">5"
 
 current_sector:

diff --git a/Boot486/run.sh b/Boot486/run.sh
index a9c515f1adf4b9bcf6a7b4ed1074d22409156a36..4fc543e1d74a0cc8a1f70cf276ba3ce150d262a8 100755 (executable)
--- a/Boot486/run.sh
+++ b/Boot486/run.sh
@@ -1,4 +1,4 @@
 #!/bin/sh
 
 set -e
-qemu-system-i386 -s -m 1G -hda ../BlackBox.img
+qemu-system-i386 -s -m 26M -hda ../BlackBox.img

diff --git a/System/Mod486/Kernel.odc b/System/Mod486/Kernel.odc
index 0930a934abbc3460d332291c68553683af90ba9a..02f3ca45d366e1c26443e26e33ad4b59faf2385f 100644 (file)
Binary files a/System/Mod486/Kernel.odc and b/System/Mod486/Kernel.odc differ