{"id":221,"date":"2004-10-03T11:02:00","date_gmt":"2004-10-03T03:02:00","guid":{"rendered":"http:\/\/www.xujiwei.com\/blog\/?p=221"},"modified":"2010-01-29T23:25:28","modified_gmt":"2010-01-29T15:25:28","slug":"write-your-own-operating-system","status":"publish","type":"post","link":"https:\/\/xujiwei.com\/blog\/2004\/10\/write-your-own-operating-system\/","title":{"rendered":"\u5199\u4f60\u81ea\u5df1\u7684\u64cd\u4f5c\u7cfb\u7edf"},"content":{"rendered":"

\u8fd9\u662f\u8f6c\u8f7d\u7684,\u539f\u6587\u53ef\u4ee5\u5728http:\/\/www.xemean.net<\/a>\u7684\u6587\u6863\u4e2d\u5fc3\u91cc\u627e\u5230.<\/p>\n

\u56e0\u4e3a\u539f\u6587\u4e2d\u7684\u4ee3\u7801\u7f16\u8bd1\u540e\u8fd0\u884c\u6709\u9519\u8bef,\u8fd9\u91cc\u6211\u628a\u6539\u8fc7\u540e\u80fd\u6b63\u786e\u8fd0\u884c\u7684\u4ee3\u7801\u8bb2\u4e00\u4e0b<\/p>\n

org\u00a00x07c00\u00a0\u00a0\u00a0\u00a0\u00a0;\u00a0\u8d77\u59cb\u5730\u5740\u662f0000:7c00<\/span><\/p>\n

jmp\u00a0begin_boot\u00a0;\u00a0\u8df3\u8fc7\u5176\u5b83\u7684\u6570\u636e\uff0c\u8df3\u8f6c\u5230\u5f15\u5bfc\u7a0b\u5e8f\u7684\u5f00\u59cb\u5904<\/span><\/p>\n

OEM_ID\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a0\"OSeg\u00a0\u00a0\u00a0\u00a0\"\u00a0\u00a0\u00a0;\u8f6f\u76d8\u4fe1\u606f,\u5177\u4f53\u8bf7\u53c2\u8003\"FAT\u683c\u5f0f\"<\/span><\/p>\n

BytesPerSector\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dw\u00a00x0200<\/p>\n

SectorsPerCluster\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a00x01<\/p>\n

ReservedSectors\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dw\u00a00x0001<\/p>\n

TotalFATs\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a00x02<\/p>\n

MaxRootEntries\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dw\u00a00x00E0<\/p>\n

TotalSectorsSmall\u00a0\u00a0\u00a0\u00a0\u00a0dw\u00a00x0B40<\/p>\n

MediaDescriptor\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a00xF0<\/p>\n

SectorsPerFAT\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dw\u00a00x0009<\/p>\n

SectorsPerTrack\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dw\u00a00x0012<\/p>\n

NumHeads\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dw\u00a00x0002<\/p>\n

HiddenSectors\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dd\u00a00x00000000<\/p>\n

TotalSectorsLarge\u00a0\u00a0\u00a0\u00a0\u00a0dd\u00a00x00000000<\/p>\n

DriveNumber\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a00x00<\/p>\n

Flags\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a00x00<\/p>\n

Signature\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a00x29<\/p>\n

VolumeID\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0dd\u00a00xFFFFFFFF<\/p>\n

VolumeLabel\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a0\"OSexample\u00a0\u00a0\"<\/p>\n

SystemID\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db\u00a0\"FAT12\u00a0\u00a0\u00a0\"<\/p>\n

print_mesg:\u00a0\u00a0;\u6253\u5370\u4fe1\u606f\u8c03\u7528<\/span><\/p>\n

mov\u00a0ah,0x13\u00a0;\u00a0\u4f7f\u7528\u4e2d\u65ad10h\u7684\u529f\u80fd13\uff0c\u5728\u5c4f\u5e55\u4e0a\u5199\u4e00\u4e2a\u5b57\u7b26\u4e32<\/span><\/p>\n

mov\u00a0al,0x00\u00a0;\u00a0\u51b3\u5b9a\u8c03\u7528\u51fd\u6570\u540e\u5149\u6807\u6240\u5904\u7684\u4f4d\u7f6e<\/span><\/p>\n

mov\u00a0bx,0x0007\u00a0;\u00a0\u8bbe\u7f6e\u663e\u793a\u5c5e\u6027<\/span><\/p>\n

mov\u00a0cx,0x20\u00a0;\u00a0\u5728\u6b64\u5b57\u7b26\u4e32\u957f\u5ea6\u4e3a32<\/span><\/p>\n

mov\u00a0dx,0x0000\u00a0;\u00a0\u5149\u6807\u7684\u8d77\u59cb\u884c\u548c\u5217<\/span><\/p>\n

int\u00a00x10\u00a0;\u00a0\u8c03\u7528BIOS\u7684\u4e2d\u65ad10h<\/span><\/p>\n

ret\u00a0;\u00a0\u8fd4\u56de\u8c03\u7528\u7a0b\u5e8f<\/span><\/p>\n

get_key:\u00a0\u00a0;\u7b49\u5f85\u6309\u952e<\/span><\/p>\n

mov\u00a0ah,0x00<\/p>\n

int\u00a00x16\u00a0;\u00a0Get_key\u4f7f\u7528\u4e2d\u65ad16h\u7684\u529f\u80fd0\uff0c\u8bfb\u53d6\u4e0b\u4e00\u4e2a\u5b57\u7b26<\/span><\/p>\n

ret<\/p>\n

clrscr:\u00a0\u00a0\u00a0;\u6e05\u5c4f<\/span><\/p>\n

mov\u00a0ax,0x0600\u00a0;\u00a0\u4f7f\u7528\u4e2d\u65ad10h\u7684\u529f\u80fd6\uff0c\u5b9e\u73b0\u5377\u5c4f\uff0c\u5982\u679cal=0\u5219\u6e05\u5c4f<\/span><\/p>\n

mov\u00a0cx,0x0000\u00a0;\u00a0\u6e05\u5c4f<\/span><\/p>\n

mov\u00a0dx,0x174f\u00a0;\u00a0\u5377\u5c4f\u81f323\uff0c79<\/span><\/p>\n

mov\u00a0bh,0\u00a0;\u00a0\u4f7f\u7528\u989c\u82720\u6765\u586b\u5145<\/span><\/p>\n

int\u00a00x10\u00a0;\u00a0\u8c03\u752810h\u4e2d\u65ad<\/span><\/p>\n

ret\u00a0\u00a0;\u8fd4\u56de<\/span><\/p>\n

begin_boot:\u00a0\u00a0;;\u5f15\u5bfc\u7a0b\u5e8f\u5f00\u59cb<\/span><\/p>\n

mov\u00a0\u00a0ax,cs\u00a0\u00a0\u00a0\u00a0;\u8bbe\u7f6e\u6bb5\u5bc4\u5b58\u5668<\/span><\/p>\n

mov\u00a0\u00a0ds,ax<\/p>\n

mov\u00a0\u00a0es,ax<\/p>\n

call\u00a0clrscr\u00a0;\u00a0\u5148\u6e05\u5c4f<\/span><\/p>\n

mov\u00a0bp,bootmesg\u00a0;\u00a0\u63d0\u4f9b\u4e32\u5730\u5740<\/span><\/p>\n

call\u00a0print_mesg\u00a0;\u00a0\u8f93\u51fa\u4fe1\u606f<\/span><\/p>\n

call\u00a0get_key\u00a0;\u00a0\u7b49\u5f85\u7528\u6237\u6309\u4e0b\u4efb\u4e00\u952e<\/span><\/p>\n

bits\u00a016\u00a0\u00a0\u00a0;\u4ee516\u4f4d\u65b9\u5f0f\u7f16\u8bd1<\/span><\/p>\n

call\u00a0clrscr\u00a0;\u00a0\u6e05\u5c4f<\/span><\/p>\n

mov\u00a0ax,0xb800\u00a0;\u00a0\u4f7fgs\u6307\u5411\u663e\u793a\u5185\u5b58<\/span><\/p>\n

mov\u00a0gs,ax ;\u00a0\u5728\u5b9e\u6a21\u5f0f\u4e0b\u663e\u793a\u4e00\u4e2a\u68d5\u8272\u7684A<\/span><\/p>\n

mov\u00a0word\u00a0[gs:0],0x641\u00a0;\u00a0\u663e\u793a<\/span><\/p>\n

call\u00a0get_key\u00a0;\u00a0\u8c03\u7528Get_key\u7b49\u5f85\u7528\u6237\u6309\u4e0b\u4efb\u4e00\u952e<\/span><\/p>\n

mov\u00a0bp,pm_mesg\u00a0;\u00a0\u8bbe\u7f6e\u4e32\u6307\u9488<\/span><\/p>\n

call\u00a0print_mesg ;\u00a0\u8c03\u7528print_mesg\u5b50\u7a0b\u5e8f<\/span><\/p>\n

call\u00a0get_key\u00a0;\u00a0\u7b49\u5f85\u6309\u952e<\/span><\/p>\n

call\u00a0clrscr\u00a0;\u00a0\u6e05\u5c4f<\/span><\/p>\n

cli\u00a0;\u00a0\u5173\u4e2d\u65ad<\/span><\/p>\n

mov\u00a0\u00a0eax,ds\u00a0\u00a0\u00a0;\u8bbe\u7f6eGDT\u7269\u7406\u5730\u5740<\/span><\/p>\n

shl\u00a0\u00a0eax,4<\/p>\n

add\u00a0\u00a0[gdtr+2],eax<\/p>\n

lgdt\u00a0[gdtr]\u00a0;\u00a0\u52a0\u8f7dGDT<\/span><\/p>\n

mov\u00a0eax,cr0\u00a0;\u8fdb\u5165\u4fdd\u62a4\u6a21\u5f0f<\/span><\/p>\n

or\u00a0\u00a0al,0x01\u00a0;\u00a0\u8bbe\u7f6e\u4fdd\u62a4\u6a21\u5f0f\u4f4d<\/span><\/p>\n

mov\u00a0cr0,eax\u00a0;\u00a0\u5c06\u66f4\u6539\u540e\u7684\u5b57\u9001\u81f3\u63a7\u5236\u5bc4\u5b58\u5668\u4e2d<\/span><\/p>\n

jmp\u00a0codesel:go_pm\u00a0\u00a0;\u8df3\u81f332\u4f4d\u4ee3\u7801<\/span><\/p>\n

bits\u00a032\u00a0\u00a0;\u4ee532\u4f4d\u65b9\u5f0f\u7f16\u8bd1<\/span><\/p>\n

go_pm:<\/p>\n

mov\u00a0ax,datasel\u00a0\u00a0;\u8bbe\u7f6e\u6bb5\u5bc4\u5b58\u5668<\/span><\/p>\n

mov\u00a0ds,ax\u00a0;\u00a0\u521d\u59cb\u5316ds\u548ces\uff0c\u4f7f\u5176\u6307\u5411\u6570\u636e\u6bb5<\/span><\/p>\n

mov\u00a0es,ax<\/p>\n

mov\u00a0ax,videosel\u00a0\u00a0;\u4f7fgs\u6307\u5411\u663e\u5b58<\/span><\/p>\n

mov\u00a0gs,ax<\/p>\n

mov\u00a0word\u00a0[gs:0],0x0400+'B'\u00a0;\u00a0\u5728\u4fdd\u62a4\u6a21\u5f0f\u4e0b\u663e\u793a\u4e00\u4e2a\u7ea2\u8272\u7684\u5b57\u7b26B<\/span><\/p>\n

jmp\u00a0$\u00a0;\u00a0\u65e0\u9650\u5faa\u73af<\/span><\/p>\n

bits\u00a016<\/p>\n

gdtr:<\/p>\n

dw\u00a0gdt_end-gdt-1\u00a0;\u00a0gdt\u7684\u957f\u5ea6<\/span><\/p>\n

dd\u00a0gdt\u00a0;\u00a0gdt\u7684\u7269\u7406\u5730\u5740<\/span><\/p>\n

gdt:\u00a0\u00a0\u00a0;\u5177\u4f53GDT\u4fe1\u606f\u8bf7\u53c2\u8003GDT\u683c\u5f0f<\/span><\/p>\n

nullsel\u00a0equ\u00a0$-gdt\u00a0;\u00a0$\u6307\u5411\u5f53\u524d\u4f4d\u7f6e\uff0c\u6240\u4ee5nullsel\u00a0=\u00a00h<\/span><\/p>\n

dd\u00a00<\/p>\n

dd\u00a00\u00a0;\u00a0\u6240\u6709\u7684\u6bb5\u63cf\u8ff0\u7b26\u90fd\u662f64\u4f4d\u7684<\/span><\/p>\n

codesel\u00a0equ\u00a0$-gdt\u00a0;\u00a0\u8fd9\u662f8h\u4e5f\u5c31\u662fgdt\u7684\u7b2c\u4e8c\u4e2a\u63cf\u8ff0\u7b26<\/span><\/p>\n

code_gdt:<\/p>\n

dw\u00a00x0ffff\u00a0;\u00a0\u6bb5\u63cf\u8ff0\u7b26\u7684\u754c\u9650\u662f4Gb<\/span><\/p>\n

dw\u00a00x0000<\/p>\n

db\u00a00x00<\/p>\n

db\u00a00x09a<\/p>\n

db\u00a00x0cf<\/p>\n

db\u00a00x00<\/p>\n

datasel\u00a0equ\u00a0$-gdt<\/p>\n

data_gdt:<\/p>\n

dw\u00a00x0ffff<\/p>\n

dw\u00a00x0000<\/p>\n

db\u00a00x00<\/p>\n

db\u00a00x092<\/p>\n

db\u00a00x0cf<\/p>\n

db\u00a00x00<\/p>\n

videosel\u00a0equ\u00a0$-gdt<\/p>\n

dw\u00a03999<\/p>\n

dw\u00a00x8000\u00a0;\u00a0\u57fa\u5740\u662f0xb8000<\/span><\/p>\n

db\u00a00x0b<\/p>\n

db\u00a00x92<\/p>\n

db\u00a00xcf<\/p>\n

db\u00a00x00<\/p>\n

gdt_end:<\/p>\n

bootmesg\u00a0db\u00a0\"Our\u00a0OS\u00a0boot\u00a0sector\u00a0loading...\u00a0\u00a0\u00a0\"\u00a0\u00a0\u00a0;\u4fe1\u606f\u6570\u636e<\/span><\/p>\n

pm_mesg\u00a0\u00a0db\u00a0\"Switching\u00a0to\u00a0protected\u00a0mode...\u00a0\u00a0\"<\/p>\n

times\u00a0510-($-$$)\u00a0db\u00a00\u00a0\u00a0;\u586b\u6ee1512\u4e2a\u5b57\u8282<\/span><\/p>\n

dw\u00a00x0AA55\u00a0\u00a0;\u5f15\u5bfc\u6247\u533a\u6807\u5fd7
\n<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

\u8fd9\u662f\u8f6c\u8f7d\u7684,\u539f\u6587\u53ef\u4ee5\u5728http:\/\/www.xemean.net\u7684\u6587\u6863\u4e2d\u5fc3\u91cc\u627e\u5230 …<\/p>\n

\u7ee7\u7eed\u9605\u8bfb »<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[5],"tags":[80,120,121],"_links":{"self":[{"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/posts\/221"}],"collection":[{"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/comments?post=221"}],"version-history":[{"count":0,"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/posts\/221\/revisions"}],"wp:attachment":[{"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/media?parent=221"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/categories?post=221"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xujiwei.com\/blog\/wp-json\/wp\/v2\/tags?post=221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}