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prot4.lst
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1991-03-20
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482 lines
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-1
1 PAGE ,132
2 TITLE Method 1
3 .286P ; Tell MASM 2.0 about 286 instructions
4 ;--------------------------------------------------------------:
5 ; Sample Program 1 :
6 ; :
7 ; This program switches into Protected Virtual Mode, changes :
8 ; the display attribute to reverse video, and returns to Real :
9 ; Mode to exit to DOS :
10 ; :
11 ; Once entered into a file, do the following: :
12 ; MASM SAMPLE1; :
13 ; LINK SAMPLE1; :
14 ; EXE2BIN SAMPLE1 SAMPLE1.COM :
15 ; DEL SAMPLE1.EXE :
16 ; :
17 ; WARNING: This program will "kill" a PC. I should only :
18 ; be run on an AT. :
19 ;--------------------------------------------------------------:
20
21 0000 bios_data_seg SEGMENT at 0040h
22 0067 ORG 0067h
23 0067 0000 io_rom_init dw ? ; dword variable in BIOS data segment
24 0069 0000 io_rom_seg dw ? ; used to store a dword address
25 006B bios_data_seg ENDS
26
27 descriptor STRUC
28 0000 0000 seg_limit dw 0 ; segment limit (1-65536 bytes)
29 0002 0000 base_lo_word dw 0 ; 24 bit physical address
30 0004 00 base_hi_byte db 0 ; (0 - (16M-1))
31 0005 00 access_rights db 0 ; access rights byte
32 0006 0000 dw 0 ; reserved_386
33 0008 descriptor ENDS
34
35 = 0070 cmos_port equ 070h
36 = 009B code_seg_access equ 10011011b ;access rights byte for code seg
37 = 0093 data_seg_access equ 10010011b ;access rights byte for data seg
38 = 00DD disable_bit20 equ 11011101b ;8042 function code to de-gate A20
39 = 00DF enable_bit20 equ 11011111b ;8042 function code to gate A20
40 = 0021 inta01 equ 021h ;8259 Int Controller #1
41 = 00A1 intb01 equ 0A1h ;8259 Int Controller #2
42 = 0060 port_a equ 060h ;8042 port A
43 = 00FE shut_cmd equ 0FEh ;cmd to 8042: shut down AT
44 = 000F shut_down equ 00Fh ;CMOS shut down byte index
45 = 0064 status_port equ 064h ;8042 status port
46 = 0001 virtual_enable equ 0001h ;LSB=1: Protected Virtual Mode
47
48
49 ;; This is a "hard coded" far jump
50 jumpfar MACRO jumpfar1,jumpfar2
51 db 0EAh
52 dw (offset jumpfar1)
53 dw jumpfar2
54 ENDM
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-2
55
56
57 SUBTTL Program entry point and data area
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-3
Program entry point and data area
58 PAGE
59 0000 cseg SEGMENT para public 'code'
60 ASSUME cs:cseg
61
62 0100 ORG 100h
63 0100 EB 32 start: jmp short main
64
65 EVEN
66 0102 gdt LABEL DWORD
67
68 = 0000 gdt_desc EQU (($-gdt)/8)*8 + 0000000000000000b
69 0102 3000 gdt1 descriptor <gdt_leng,,,data_seg_access,>
70 0104 0000
71 0106 00
72 0107 93
73 0108 0000
74
75 = 0008 cs_code EQU (($-gdt)/8)*8 + 0000000000000000b
76 010A 0261 R gdt2 descriptor <cseg_leng,,,code_seg_access,>
77 010C 0000
78 010E 00
79 010F 9B
80 0110 0000
81
82 = 0010 cs_data EQU (($-gdt)/8)*8 + 0000000000000000b
83 0112 0261 R gdt3 descriptor <cseg_leng,,,data_seg_access,>
84 0114 0000
85 0116 00
86 0117 93
87 0118 0000
88
89 = 0018 ss_desc EQU (($-gdt)/8)*8 + 0000000000000000b
90 011A FFFF gdt4 descriptor <0FFFFh,,,data_seg_access,>
91 011C 0000
92 011E 00
93 011F 93
94 0120 0000
95
96 = 0020 ds_desc equ (($-gdt)/8)*8 + 0000000000000000b
97 0122 FFFF gdt5 descriptor <0FFFFh,,,data_seg_access,>
98 0124 0000
99 0126 00
100 0127 93
101 0128 0000
102
103 = 0028 es_desc equ (($-gdt)/8)*8 + 0000000000000000b
104 012A FFFF gdt6 descriptor <0FFFFh,,,data_seg_access,>
105 012C 0000
106 012E 00
107 012F 93
108 0130 0000
109
110 = 0030 gdt_leng EQU $-gdt
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-4
Program entry point and data area
111 PAGE
112 ;--------------------------------------------------------------:
113 ; Format of the Segment Selector Component: :
114 ; :
115 ; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ :
116 ; | INDEX +TI+ RPL + :
117 ; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ :
118 ; :
119 ; TI = Table Indicator (0=GDT, 1=LDT) :
120 ; RPL = Requested Privelege Level (00 = highest; 11 = Lowest) :
121 ;--------------------------------------------------------------:
122 ; Format of the Global Descriptor Table :
123 ; .-----------+ +---> TI :
124 ; V | |++-> RPL :
125 ; GDT ==> +---------------+ | ||| :
126 ; | GDT_DESC | --+ 0000000000000000b :
127 ; +---------------+ :
128 ; | CS_CODE | 0000000000001000b :
129 ; +---------------+ :
130 ; | CS_DATA | 0000000000010000b :
131 ; +---------------+ :
132 ; | SS_DESC | 0000000000011000b :
133 ; +---------------+ :
134 ; | DS_DESC | 0000000000100000b :
135 ; +---------------+ :
136 ; | ES_DESC | 0000000000101000b :
137 ; +---------------+ :
138 ;--------------------------------------------------------------:
139
140 0132 00 i8259_1 db ? ; store for status of 8259 #1
141 0133 00 i8259_2 db ? ; store for status of 8259 #2
142
143 SUBTTL Program Main
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-5
Program Main
144 PAGE
145 ;--------------------------------------------------------------:
146 ; MAIN :
147 ;--------------------------------------------------------------:
148 ASSUME ds:cseg
149 0134 main PROC ;ES=DS=CS
150 0134 FC cld ;forward
151
152 0135 8C CA mov dx,cs ;form 24bit address out of
153 0137 B9 0102 R mov cx,offset gdt ; CS:GDT
154 013A E8 0237 R call form_24bit_address
155 013D 89 16 0104 R mov gdt1.base_lo_word,dx ;DESC now points to gdt
156 0141 88 0E 0106 R mov gdt1.base_hi_byte,cl
157
158 0145 8C CA mov dx,cs ;form 24bit address out of
159 0147 33 C9 xor cx,cx ; CS:0000
160 0149 E8 0237 R call form_24bit_address
161 014C 89 16 010C R mov gdt2.base_lo_word,dx ;CS_CODE now points to
162 0150 88 0E 010E R mov gdt2.base_hi_byte,cl ; CSEG as a code segment
163 0154 89 16 0114 R mov gdt3.base_lo_word,dx ;CS_DATA now points to
164 0158 88 0E 0116 R mov gdt3.base_hi_byte,cl ; CSEG as a data segment
165
166 015C 8C D2 mov dx,ss ;form 24bit address out of
167 015E 33 C9 xor cx,cx ; SS:0000
168 0160 E8 0237 R call form_24bit_address
169 0163 89 16 011C R mov gdt4.base_lo_word,dx ;SS_DESC now points to
170 0167 88 0E 011E R mov gdt4.base_hi_byte,cl ; stack segment
171
172 016B 2E: 0F 01 16 0102 R lgdt DWORD PTR Cs:gdt ;Load the GDTR
prot4.ASM(142): warning A4057: Illegal size for operand
173
174 0171 B4 DF mov ah,enable_bit20 ;gate address bit 20 on
175 0173 E8 0215 R call gate_a20
176 0176 0A C0 or al,al ; was the command accepted?
177 0178 74 2E jz m_10 ; go if yes
178 017A BA 0183 R mov dx,offset gate_failure ;print error msg
179 017D B4 09 mov ah,9 ; and terminate
180 017F CD 21 int 21h
181 0181 CD 20 int 20h
182
183 0183 41 64 64 72 65 73 gate_failure db "Address line A20 failed to Gate open$"
184 73 20 6C 69 6E 65
185 20 41 32 30 20 66
186 61 69 6C 65 64 20
187 74 6F 20 47 61 74
188 65 20 6F 70 65 6E
189 24
190
191 01A8 FA m_10: cli ;No interrupts
192
193 01A9 E4 21 in al,inta01 ;get status of Int Controller #1
194 01AB A2 0132 R mov i8259_1,al
195 01AE E4 A1 in al,intb01 ;get status of Int Controller #2
196 01B0 A2 0133 R mov i8259_2,al
197
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-6
Program Main
198 ASSUME ds:bios_data_seg
199 01B3 BA ---- R mov dx,bios_data_seg ;Real Mode Return address
200 01B6 8E DA mov ds,dx
201 01B8 8C 0E 0069 R mov io_rom_seg,cs
202 01BC C7 06 0067 R 024B R mov io_rom_init,offset real
203
204 01C2 B0 0F mov al,shut_down ;Set shutdown byte
205 01C4 E6 70 out cmos_port,al ; to shut down x05.
206 01C6 EB 00 jmp short $+2 ;I/O delay
207 01C8 B0 05 mov al,5
208 01CA E6 71 out cmos_port+1,al
209
210 01CC B8 0001 mov ax,virtual_enable ;machine status word needed to
211 01CF 0F 01 F0 lmsw ax ;switch to virtual mode
212 jumpfar m_20,cs_code ;Must purge prefetch queue
213 01D2 EA 1 db 0EAh
214 01D3 01D7 R 1 dw (offset m_20)
215 01D5 0008 1 dw cs_code
216
217 01D7 m_20: ASSUME ds:cseg ;IN VIRTUAL MODE ...
218 01D7 B8 0018 mov ax,ss_desc ;stack segment selector
219 01DA 8E D0 mov ss,ax ;user's ss+sp is not a descriptor
220
221 01DC B8 0010 mov ax,cs_data
222 01DF 8E D8 mov ds,ax ;DS = CSEG as data
223
224 01E1 C7 06 0124 R 8000 mov gdt5.base_lo_word,8000h ;use 8000 for COLOR
225 01E7 C6 06 0126 R 0B mov gdt5.base_hi_byte,0Bh
226 01EC C7 06 012C R 8000 mov gdt6.base_lo_word,8000h
227 01F2 C6 06 012E R 0B mov gdt6.base_hi_byte,0Bh
228
229 01F7 B8 0020 mov ax,ds_desc
230 01FA 8E D8 mov ds,ax
231 01FC B8 0028 mov ax,es_desc
232 01FF 8E C0 mov es,ax
233 0201 B9 07D0 mov cx,80*25
234 0204 33 F6 xor si,si
235 0206 33 FF xor di,di
236 0208 AD m_30: lodsw
237 0209 B4 65 mov ah,65h ;attribute reverse video
238 020B AB stosw
239 020C E2 FA loop m_30
240
241 020E B0 FE mov al,shut_cmd ;shutdown cmd
242 0210 E6 64 out status_port,al ;get back into REAL mode
243 0212 F4 m_40: hlt
244 0213 EB FD jmp short m_40
245
246 SUBTTL Gate A20
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-7
Gate A20
247 PAGE
248 ;--------------------------------------------------------------:
249 ; GATE_A20 :
250 ; This routine controls a signal which gates address bit 20. :
251 ; The gate A20 signal is an output of the 8042 slave processor.:
252 ; Address bit 20 should be gated on before entering protected :
253 ; mode. It should be gated off after entering real mode from :
254 ; protected mode. :
255 ; Input: (AH)=0DDh addr bit 20 gated off (A20 always 0) :
256 ; (AH)=0DFh addr bit 20 gated on (286 controls A20) :
257 ; Output: (AL)=0 operation successful. 8042 has accepted cmd :
258 ; (AL)=2 Failure -- 8042 unable to accept command. :
259 ;--------------------------------------------------------------:
260 0215 gate_a20 PROC
261 0215 FA cli ;disable ints while using 8042
262 0216 E8 022C R call empty_8042 ;insure 8042 input buffer empty
263 0219 75 10 jnz gate_a20_01 ;ret if 8042 unable to accept cmd
264 021B B0 D1 mov al,0D1h ;8042 command to write output port
265 021D E6 64 out status_port,al ;output cmd to 8042
266 021F E8 022C R call empty_8042 ;wait for 8042 to accept command
267 0222 75 07 jnz gate_a20_01 ;ret if 8042 unable to accept cmd
268 0224 8A C4 mov al,ah ;8042 port data
269 0226 E6 60 out port_a,al ;output port data to 8042
270 0228 E8 022C R call empty_8042 ;wait for 8042 to port data
271 022B gate_a20_01:
272 022B C3 ret
273 022C gate_a20 ENDP
274 ;--------------------------------------------------------------:
275 ; EMPTY_8042 :
276 ; This routine waits for the 8042 buffer to empty :
277 ; Input: None :
278 ; Output: (AL)=0 8042 input buffer empty (ZF=1) :
279 ; (AL)=2 Time out, 8042 buffer full (ZF=0) :
280 ;--------------------------------------------------------------:
281 022C empty_8042 PROC
282 022C 51 push cx ;save CX
283 022D 2B C9 sub cx,cx ;CX=0 will be the time out value
284 022F empty_8042_01:
285 022F E4 64 in al,status_port ;read 8042 status port
286 0231 24 02 and al,00000010b ;test input buffer full flag (D1)
287 0233 E0 FA loopnz empty_8042_01 ;loop until input buffer empty
288 ; or time out
289 0235 59 pop cx ;restore CX
290 0236 C3 ret
291 0237 empty_8042 ENDP
292
293 SUBTTL form_24bit_address
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-8
form_24bit_address
294 PAGE
295 ;--------------------------------------------------------------:
296 ; FORM_24BIT_ADDRESS :
297 ; Input: DX has some segment :
298 ; CX has some offset :
299 ; Output: DX has base_lo_word :
300 ; CL has base_hi_byte :
301 ;--------------------------------------------------------------:
302 0237 form_24bit_address PROC
303 0237 50 push ax
304 ;DX == s15 s14 s13 s12 s11 ... s04 s03 s02 s01 s00
305 0238 C1 C2 04 rol dx,4
306 ;DX == s11 ... s04 s03 s02 s01 s00 s15 s14 s13 s12
307 023B 8B C2 mov ax,dx
308 ;AX == s11 ... s04 s03 s02 s01 s00 s15 s14 s13 s12
309 023D 80 E2 F0 and dl,0F0h
310 ;DX == s11 ... s04 s03 s02 s01 s00 0 0 0 0
311 0240 25 000F and ax,0Fh
312 ;AX == 0 ... 0 0 0 0 0 s15 s14 s13 s12
313 0243 03 D1 add dx,cx ;form_24bit_address
314 0245 8B C8 mov cx,ax ;get base_hi_byte in CL
315 0247 12 CD adc cl,ch ;carry in (CH=0)
316 0249 58 pop ax
317 024A C3 ret
318 024B form_24bit_address ENDP
319
320 SUBTTL Real Mode re-entry point.
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Page 1-9
Real Mode re-entry point.
321 PAGE
322 ASSUME ds:cseg ;IN REAL MODE ...
323
324 024B 8C CA real: mov dx,cs
325 024D 8E DA mov ds,dx ;DS = CS
326 024F B4 DD mov ah,disable_bit20 ;gate address bit 20 on
327 0251 E8 0215 R call gate_a20
328 0254 A0 0132 R mov al,i8259_1
329 0257 E6 21 out inta01,al ;set status of Int Controller #1
330 0259 A0 0133 R mov al,i8259_2
331 025C E6 A1 out intb01,al ;set status of Int Controller #2
332
333 025E FB sti ;turn the interrupts on
334 025F CD 20 int 20h ;back to DOS
335
336 0261 main ENDP
337 = 0261 cseg_leng EQU $
338 0261 cseg ENDS
339 END start
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Symbols-1
Macros:
N a m e Lines
jumpfar . . . . . . . . . . . . 3
Structures and Records:
N a m e Width # fields
Shift Width Mask Initial
descriptor . . . . . . . . . . . 0008 0005
seg_limit . . . . . . . . . . 0000
base_lo_word . . . . . . . . . 0002
base_hi_byte . . . . . . . . . 0004
access_rights . . . . . . . . 0005
Segments and Groups:
N a m e Length Align Combine Class
bios_data_seg . . . . . . . . . 006B AT 0040
cseg . . . . . . . . . . . . . . 0261 PARA PUBLIC 'code'
Symbols:
N a m e Type Value Attr
cmos_port . . . . . . . . . . . NUMBER 0070
code_seg_access . . . . . . . . NUMBER 009B
cs_code . . . . . . . . . . . . NUMBER 0008
cs_data . . . . . . . . . . . . NUMBER 0010
cseg_leng . . . . . . . . . . . NEAR 0261 cseg
data_seg_access . . . . . . . . NUMBER 0093
disable_bit20 . . . . . . . . . NUMBER 00DD
ds_desc . . . . . . . . . . . . NUMBER 0020
empty_8042 . . . . . . . . . . . N PROC 022C cseg Length = 000B
empty_8042_01 . . . . . . . . . L NEAR 022F cseg
enable_bit20 . . . . . . . . . . NUMBER 00DF
es_desc . . . . . . . . . . . . NUMBER 0028
form_24bit_address . . . . . . . N PROC 0237 cseg Length = 0014
gate_a20 . . . . . . . . . . . . N PROC 0215 cseg Length = 0017
gate_a20_01 . . . . . . . . . . L NEAR 022B cseg
gate_failure . . . . . . . . . . L BYTE 0183 cseg
gdt . . . . . . . . . . . . . . L DWORD 0102 cseg
gdt1 . . . . . . . . . . . . . . L QWORD 0102 cseg
gdt2 . . . . . . . . . . . . . . L QWORD 010A cseg
gdt3 . . . . . . . . . . . . . . L QWORD 0112 cseg
gdt4 . . . . . . . . . . . . . . L QWORD 011A cseg
gdt5 . . . . . . . . . . . . . . L QWORD 0122 cseg
Microsoft (R) Macro Assembler Version 5.10 3/20/91 22:38:53
Method 1 Symbols-2
gdt6 . . . . . . . . . . . . . . L QWORD 012A cseg
gdt_desc . . . . . . . . . . . . NUMBER 0000
gdt_leng . . . . . . . . . . . . NUMBER 0030
i8259_1 . . . . . . . . . . . . L BYTE 0132 cseg
i8259_2 . . . . . . . . . . . . L BYTE 0133 cseg
inta01 . . . . . . . . . . . . . NUMBER 0021
intb01 . . . . . . . . . . . . . NUMBER 00A1
io_rom_init . . . . . . . . . . L WORD 0067 bios_data_seg
io_rom_seg . . . . . . . . . . . L WORD 0069 bios_data_seg
m_10 . . . . . . . . . . . . . . L NEAR 01A8 cseg
m_20 . . . . . . . . . . . . . . L NEAR 01D7 cseg
m_30 . . . . . . . . . . . . . . L NEAR 0208 cseg
m_40 . . . . . . . . . . . . . . L NEAR 0212 cseg
main . . . . . . . . . . . . . . N PROC 0134 cseg Length = 012D
port_a . . . . . . . . . . . . . NUMBER 0060
real . . . . . . . . . . . . . . L NEAR 024B cseg
shut_cmd . . . . . . . . . . . . NUMBER 00FE
shut_down . . . . . . . . . . . NUMBER 000F
ss_desc . . . . . . . . . . . . NUMBER 0018
start . . . . . . . . . . . . . L NEAR 0100 cseg
status_port . . . . . . . . . . NUMBER 0064
virtual_enable . . . . . . . . . NUMBER 0001
@Cpu . . . . . . . . . . . . . . TEXT 1415
@FileName . . . . . . . . . . . TEXT prot4
@Version . . . . . . . . . . . . TEXT 510
300 Source Lines
303 Total Lines
62 Symbols
46452 Bytes symbol space free
1 Warning Errors
0 Severe Errors
