BIOS Data Area(Detailed)

7/25/2019 BIOS Data Area(Detailed)

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When power is applied to the computer, the BIOS Data Area is created at memory location 0040:0000hwith a typical size of !! "ytes#

O$set%e&

O$setDec

BIOSSer'ice

(ield Size (unction

00h 0 Int )4h "ytesBase I*O address for serial port ) +communications port) -O. )/

0h Int )4h "ytesBase I*O address for serial port +communications port -O. /

04h 4 Int )4h "ytesBase I*O address for serial port +communications port -O. /

01h 1 Int )4h "ytesBase I*O address for serial port 4 +communications port4 -O. 4/

02h 2 Int )3h "ytesBase I*O address for parallel port ) +printer port ) 56)/

0Ah )0 Int )3h "ytesBase I*O address for parallel port +printer port 56/

0-h ) Int )3h "ytesBase I*O address for parallel port +printer port 56/

07h )4 5OS6 "ytesBase I*O address for parallel port 4 +printer port 4 56

4/ +Only found in 5-*86 systems/)0h )1 Int ))h "ytes 79uipment Word

Bits )!)4 indicate the num"er of parallel portsinstalled

00" ) parallel port

0)" parallel ports

0" parallel ports

Bits )) are reser'ed

Bits )); indicate the num"er of serial ports installed

000" none

00)" ) serial port

00" serial ports

00" serial ports

004" 4 serial ports

Bit 2 is reser'ed

Bit 31 indicate the num"er of <oppy dri'es installed

0" ) <oppy dri'e

)" <oppy dri'es

Bits !4 indicate the 'ideo mode

00" 7=A or later

0)" color 40&!

)0" color 20&!

))" monochrome 20&!

Bit is reser'ed

Bit indicates if a 5S* mouse is installed

0" not installed

)" installed

Bit ) indicated if a math coprocessor is installed

0" not installed

)" installed

Bit 0 indicated if a "oot <oppy is installed

0" not installed

)" installed

)h )2 5OS6 ) "yte Interrupt <a> .anufacturin> test

)h ); Int )h "ytes .emory size in ?"

)!h )

"ytes 7rror codes for A6@ Adapter memory size for 5- and 86



)3h Int )1h ) "yte ?ey"oard shift <a>s )

Bit 3 indicates if Insert is on or o$

0" Insert o$

)" Insert on

Bit 1 indicates if -apsoc is on or o$

0" -apsoc o$

)" -apsoc on

Bit ! indicates if Cumoc is on or o$

0" Cumoc o$

)" Cumoc on

Bit 4 indicates if Scrolloc is on or o$

0" Scrolloc o$

)" Scrolloc on

Bit indicates if the Alt ey is up or down

0" Alt ey is up

)" Alt ey is down

Bit indicates if the -ontrol ey is up or down

0" -ontrol ey is up

)" -ontrol ey is down

Bit ) indicates if the eft Shift ey is up or down

0" eft Shift ey is up

)" eft Shift ey is down

Bit 0 indicates if the i>ht Shift ey is up or down

0" i>ht Shift ey is up

)" i>ht Shift ey is down

)2h Int )1h ) "yte ?ey"oard shift <a>s

Bit 3 indicates if the Insert ey is up or down

0" Insert ey is up

)" Insert ey is down

Bit 1 indicates if the -apsoc ey is up or down

0" -apsoc is ey is up

)" -apsoc ey is down

Bit ! indicates if the Cumoc ey is up or down

0" Cumoc ey is up

)" Cumloc ey is down

Bit 4 indicates if the Scrolloc ey is up or down

0" Scrolloc ey is up

)" Scrolloc ey is down

Bit indicates if the 5ause ey is acti'e or inacti'e

0" pause ey is inacti'e

)" 5ause ey is acti'e

Bit indicates if the Syse> ey is up or down

0" Syse> ey is up

)" Syse> ey is down

Bit ) indicates if the eft Alt ey is up or down

0" eft Alt ey is up

)" eft Alt ey is down

Bit 0 indicates if the i>ht Alt ey is up or down

0" i>ht Alt ey is up

)" i>ht Alt ey is down

);h 4 Int 0;h ) "yte Alt Cumpad wor area



)Ah 1 Int )1h "ytes5ointer to the address of the ne&t character in theey"oard "u$er

)-h 2 Int )1h "ytes5ointer to the address of the last character in heey"oard "u$er

)7h 10 Int )1h "ytes ?ey"oard "u$er

7h 1) Int )h ) "yte (loppy dis dri'e cali"ration status

Bits 34 are reser'ed

Bit <oppy dri'e +5-, 86/

Bit <oppy dri'e +5-, 86/

Bit ) <oppy dri'e )

Bit 0 <oppy dri'e 0

0" indicates not cali"rated

)" indicates cali"rated

(h 1 Int )h ) "yte (loppy dis dri'e motor status

Bit 3 indicates current operation

0" read or 'erify operation

)" write or format operation

Bit 1 is not used

Bit !4 indicates dri'e select

00" Dri'e 0

0)" Dri'e )

)0" Dri'e +5-, 86/

))" Dri'e 4 +5-, 86/

Bit indicates dri'e motor

0" motor o$

)" motor on

Bit indicates dri'e motor

0" motor o$

)" motor on

Bit ) indicates dri'e 0 motor

0" motor o$

)" motor on

0" motor o$

)" motor on

40h 1 Int )h ) "yte (loppy dis dri'e motor timeout

4)h 14 Int )h ) "yte (loppy dis dri'e statusBit 3 indicates dri'e ready status

0" dri'e ready

)" dri'e not ready +time out/

Bit 1 indicates see status

0" no see error detected

)" indicates a see error was detected

Bit ! indicates <oppy dis controller test

0" <oppy dis controller passed

)" <oppy dis controller failed

Bit 40 error codes

00000" no errors

0000)" ille>al function re9uested

000)0" address mar not found

000))" write protect error

00)00" sector not found

00))0" disette chan>e line acti'e



0)000" D.A o'errun

0)00)" D.A "oundary error

0))00" unnown media type

)0000" -- error durin> read

4h 1! Int )h ) "yte %ard dis and <oppy controller status re>ister 0

Bit 31 indicate the interrupt code

00" command completed normally

0)" command terminated a"normally

)0" a"normal termination, ready line on, or disettechan>ed

))" see command not completed

Bit ! indicated see command

0" see command not completed

)" see command completed

Bit 4 indicated dri'e fault

0" no dri'e fault

)" dri'e fault

Bit indicates dri'e ready

0" dri'e ready

)" dri'e not ready

Bit indicates head state when interrupt occurred

00" dri'e 0

0)" dri'e )

)0" dri'e +5-, 86/

))" dri'e +5-, 86/

Bit )0 indicates dri'e select

00" dri'e 0

0)" dri'e )

)0" dri'e +5-, 86/

))" dri'e +5-, 86/

4h 11 Int )h ) "yte (loppy dri'e controller status re>ister )

Bit 30 indicates no error

Bit 3, )" indicates attempted access "eyond lastcylinder

Bit 1, 0" not used

Bit !, )" -- error durin> read

Bit 4, )" D.A o'errun

Bit , 0" not used

Bit , )" Sector not found or readin> disette ID failed

Bit ), )" medium write protected

Bit 0, )" missin> address mar

44h 13 Int )h ) "yte (loppy dri'e controller status re>ister

Bit 3, 0" not used

Bit 1, )" deleted data address mar

Bit !, )" -- error detected

Bit 4, )" wron> cylinder

Bit , )" condition of e9ual durin> 'erify

Bit , )" sector not found durin> 'erify

Bit ), )" "ad cylinder

Bit 0, )" address mar not found durin> read

4!h 12 Int )h ) "yte (loppy dis controller: cylinder num"er

41h 1; Int )h ) "yte (loppy dis controller: head num"er



43h 30 Int )h ) "yte (loppy dis controller: sector num"er

42h 3)

) "yte (loppy dis controller: num"er of "yte written

4;h 3 Int )0h ) "yte Acti'e 'ideo mode settin>

4Ah 34 Int )0h "ytesCum"er of te&tcolumns per row for the acti'e 'ideomode

4-h 31 Int )0h "ytes Size of acti'e 'ideo in pa>e "ytes

47h 32 Int )0h "ytesO$set address of the acti'e 'ideo pa>e relati'e to thestart of 'ideo A.

!0h 20 Int )0h "ytes -ursor position for 'ideo pa>e 0

!h 2 Int )0h "ytes -ursor position for 'ideo pa>e )

!4h 24 Int )0h "ytes -ursor position for 'ideo pa>e

!1h 21 Int )0h "ytes -ursor position for 'ideo pa>e

!2h 22 Int )0h "ytes -ursor position for 'ideo pa>e 4

!Ah ;0 Int )0h "ytes -ursor position for 'ideo pa>e !

!-h ; Int )0h "ytes -ursor position for 'ideo pa>e 1

!7h ;4 Int )0h "ytes -ursor position for 'ideo pa>e 3

10h ;1 Int )0h "ytes -ursor shape

1h ;3 Int )0h ) "yte Acti'e 'ideo pa>e

1h ;; Int )0h "ytes I*O port address for the 'ideo display adapter1!h )00 Int )0h ) "yte Eideo display adapter internal mode re>ister

Bit 3, 0" not used

Bit 1, 0" not used

Bit !

0" attri"ute "it controls "ac>round intensity

)" attri"ute "it controls "linin>

Bit 4, )" mode 1 >raphics operation

Bit indicates 'ideo si>nal

0" 'ideo si>nal disa"led

)" 'ideo si>nal ena"led

Bit indicates color operation

0" color operation

)" monochrome operation

Bit ), )" mode 4*! >raphics operation

Bit 0, )" mode * test operation

11h )0) Int )0h ) "yte -olor palette

Bit 3, 0" not used

Bit 1, 0" not used

Bit ! indicates mode ! fore>round colors

0" >reen*red*yellow

)" cyan*ma>enta*white

Bit 4 indicates "ac>round color

0" normal "ac>round color

)" intensiFed "ac>round color

Bit indicates intensiFed "order color +mode / and"ac>round color +mode !/

Bit indicates red

Bit ) indicates >reen

Bit 0 indicates "lue

13h )0

"ytes Adapter O. o$set address

1;h )01

"ytes Adapter O. se>ment address

1Bh )03

) "yte ast interrupt +not 5-/

Bit 3 indicates IG 3 hardware interrupt

0" did not occur

0) did occur




0" did not occur

0) did occur

Bit ! indicates IG ! hardware interrupt

0" did not occur

0) did occur


0" did not occur

0) did occur

Bit indicates IG hardware interrupt

0" did not occur

0) did occur

Bit indicates IG hardware interrupt

0" did not occur

0) did occur

Bit ) indicates IG ) hardware interrupt

0" did not occur

0) did occur


0" did not occur

0) did occur

1-h ))) Int )Ah 4 "ytes -ounter for Interrupt )Ah

30c )) Int )Ah ) "yte 6imer 4 hour <a>

3)h )) Int )1h ) "yte ?ey"oard -trlBrea <a>

3h ))! 5OS6 "ytes Soft reset <a>

34h ))1 Int )h ) "yte Status of last hard dis operation

00h no errors

0)h in'alid function re9uested

0h address mar not found

04h sector not found

0!h reset failed

01h remo'a"le media chan>ed

03h dri'e parameter acti'ity failed

02h D.A o'errun

0;h D.A "oundary o'errun

0Ah "ad sector <a> detected

0Bh "ad trac detected

0Dh in'alid num"er of sectors on format

07h control data address mar detected

0(h D.A ar"itration le'el out of ran>e

)0h uncorrecta"le 7-- or -- error

))h 7-- corrected data error

0h >eneral controller failure

40h see operation failed

20h timeout

AAh dri'e not ready

BBh undeFned error occurred

--h write fault on selected dri'e

70h status error or error re>ister is zero

((h sense operation failed

3!h ))3 Int )h ) "yte Cum"er of hard dis dri'es

31h ))2 Int )h ) "yte %ard dis control "yte



Bit 3

0" ena"les retries on dis error

)" disa"les retries on dis error

Bit 1

0" ena"les reties on dis error

)" ena"les reties on dis error

Bit !, 0" not used

Bit 4, 0" not used

Bit

0" dri'e has less than 2 heads

)" dri'e has more than 2 heads

Bit , 0" not used

Bit ), 0" not used

Bit 0, 0" not used

33h )); Int )h ) "yte O$set address of hard dis I*O port +86/

32h )0 Int )3h ) "yte 5arallel port ) timeout

3;h )) Int )3h ) "yte 5arallel port timeout

3Ah ) Int )3h ) "yte 5arallel port timeout

3Bh )

) "yte5arallel port 4 timeout +5-, 86/ support for 'irtual D.Aser'ices +EDS/

Bit 3, 0" not used

Bit 1, 0" not used

Bit ! indicates 'irtual D.A ser'ices

0" not supported

)" supported

Bit 4, 0" not used

Bit indicates chainin> on interrupt 4Bh

0" not re9uired

)" re9uired

Bit , 0" not used

Bit ), 0" not used

Bit 0, 0" not used

3-h )4 Int )4h ) "yte Serial port ) timeout

3Dh )! Int )4h ) "yte Serial port timeout

37h )1 Int )4h ) "yte Serial port timeout

3(h )3 Int )4h ) "yte Serial port 4 timeout20h ); Int )1h "ytes Startin> address of ey"oard "u$er

2h )) Int )1h "ytes 7ndin> address of ey"oard "u$er

24h ) Int )0h ) "yte Cum"er of 'ideo rows +minus )/

2!h )4 Int )0h "ytes Cum"er of scan lines per character

23h )! Int )0h ) "yte Eideo display adapter options

Bit 3 indicates "it 3 of the last 'ideo mode

0" clear display "u$er when settin> mode

)" do not clear the display "u$er

Bit 14 indicates the amount of memory on the 'ideo

display adapter

000" 14?"

00)" )2?"

0)0" );?"

0))" !1?"

)00" !)?"

))0 )04?" or more

Bit indicates 'ideo su"system



0" not acti'e

)" acti'e

Bit is reser'ed

Bit ) indicates monitor type

0" color

)" monochrome

Bit 0 indicates alphanumeric cursor emulation

0" disa"led

)" ena"led

22h )1 Int )0h ) "yte Eideo display adapter switches

Bit 3 indicates state of feature connector line )

Bit 1 indicates state of feature connector line 0

Bit !4 not used

Bit 0 indicate adapter type switch settin>s

0000" .DA*color 40&!

000)" .DA*color 20&!

00)0" .DA*hi>hresolution 20&!

00))" .DA*hi>hresolution enhanced

0)00" -=A 40&!*monochrome

0)0)" -=A 20&!*monochrome

0))0" color 40&!*.DA

0)))" color 20&!*.DA

)000" hi>hresolution 20&!*.DA

)00)" hi>hresolution enhanced*.DA

)0)0" monochrome*-=A 40&!

)0))" monochrome*-=A 20&!

2;h )3 Int )0h ) "yte E=A 'ideo <a>s )

Bit 3 and 4 indicate scanline mode

00" !0line mode

0)" 400line mode

)0" 00line mode

Bit 1 indicates display switch

0" disa"led

)" ena"led

Bit ! is reser'ed

Bit indicates default palette loadin>

0" disa"led

)" ena"led

Bit indicates monitor type

0" color

)" monochrome

Bit ) indicates >ray scale summin>

0" disa"led

)" ena"led

Bit 0 indicates E=A acti'e state

0" E=A inacti'e

)" E=A acti'e

2Ah )2 Int )0h ) "yte E=A 'ideo <a>s

2Bh ); Int )h ) "yte (loppy dis conF>uration data

Bit 31 indicate last data sent to the controller

00" !00 ?"it*sec*sec



0)" 00 ?"it*sec

)0" !0 ?"it*sec

))" rate not set or ) ."it*sec

Bit !4 indicate last dri'e steprate sent to the controller

00" 2ms

0)" 3ms

)0" 1ms

))" !ms

Bit indicate data rate, set at start of operation +Bits31/

Bit )0 not used

2-h )40 Int )h ) "yte %ard dis dri'e controller status

Bit 3 indicates controller state

0" controller not "usy

)" controller "usy

Bit 1 indicates dri'e ready state

0" dri'e selected not ready

)" dri'e selected ready

Bit ! indicates write fault

0" write fault did not occur

)" write error occurred

Bit 4 indicates see state

0" dri'e selected seein>

)" dri'e selected see complete

Bit indicates data re9uest

0" data re9uest is inacti'e

)" data re9uest is acti'e

Bit indicates data correction

0" data not corrected

)" data corrected

Bit ) indicates inde& pulse state

0" inde& pulse inacti'e

)" inde& pulse acti'e

Bit 0 indicates error

0" no error

)" error in pre'ious command

2Dh )4) Int )h ) "yte %ard dis dri'e error

Bit 3 indicates "ad sector

0" not used

)" "ad sector detected

Bit 1 indicated 7-- error

0" not used

)" uncorrecta"le 7-- error occurred

Bit ! indicates media state

0" not used

)" media chan>ed

Bit 4 indicates sector state

0" not used

)" ID or tar>et sector not found

Bit indicates media chan>e re9uest state

0" not used



)" media chan>e re9uested

Bit indicates command state

0" not used

)" command a"orted

Bit ) indicates dri'e trac error

0" not used

)" trac 0 not found

Bit 0 indicates address mar

0" not used

)" address mar not found

27h )4 Int )h ) "yte %ard dis dri'e tas complete <a>

2(h )4 Int )h ) "yte (loppy dis dri'e information

Bit 3 not used

Bit 1 indicates dri'e ) type determination

0" not determined

)" determined

Bit ! indicates dri'e ) multirate status

0" no

)" yes

Bit 4 indicates disette ) chan>e line detection

0" no

)" yes

Bit not used

Bit indicates dri'e 0 type determination

0" not determined

)" determined

Bit ) indicates dri'e 0 multirate status

0" no

)" yes

Bit 0 indicates disette 0 chan>e line detection

0" no

)" yes

;0h )44 Int )h ) "yte Disette 0 media state

Bit 31 indicate transfer rate

00" !00 ?"it*sec

0)" 00 ?"it*sec

)0" !0 ?"it*sec

))" ) ."it*sec

Bit ! indicates dou"le steppin>

0" not re9uired

)" re9uired

Bit 4 indicates media in <oppy dri'e

0" unnown media

)" nown media

Bit not used

Bit 0 indicates last access

000" tryin> 10 media in 10? dri'e

00)" tryin> 10? media in )#. dri'e

0)0" tryin> )#. media in )#. dri'e

0))" nown 10? media on 10? dri'e

)00" nown 10? media in )#. dri'e



)0)" nown )#. media in )#. dri'e

))0" not used

)))" 30? media in 30? dri'e or )#44. media in)#44. dri'e

;)h )4! Int )h ) "yte Disette ) media state

Bit 31 indicate transfer rate

00" !00 ?"it*sec

0)" 00 ?"it*sec

)0" !0 ?"it*sec

))" ) ."it*sec

Bit ! indicates dou"le steppin>

0" not re9uired

)" re9uired

Bit 4 indicates media in <oppy dri'e

0" unnown media

)" nown media

Bit not used

Bit 0 indicates last access

000" tryin> 10 media in 10? dri'e

00)" tryin> 10? media in )#. dri'e

0)0" tryin> )#. media in )#. dri'e

0))" nown 10? media on 10? dri'e

)00" nown 10? media in )#. dri'e

)0)" nown )#. media in )#. dri'e

))0" not used

)))" 30? media in 30? dri'e or )#44. media in)#44. dri'e

;h )41 Int )h ) "yte Disette 0 operational startin> state

Bit 3 indicates data transfer rate

00" !00 ?"it*sec

0)" 00 ?"it*sec

)0" !0 ?"it*sec

))" ) ."it*sec

Bits ! not used

Bit indicates dri'e determination

0" dri'e type not determined

)" dri'e type determined

Bit ) indicates dri'e multirate status

0" dri'e is not multirate

)" dri'e is multirate

Bit 0 indicates chan>e line detection

0" no chan>e line detection

)" chan>e line detection

;h )43 Int )h ) "yte Disette ) operational startin> status

Bit 3 indicates data transfer rate

00" !00 ?"it*sec

0)" 00 ?"it*sec

)0" !0 ?"it*sec

))" ) ."it*sec

Bits ! not used

Bit indicates dri'e determination

0" dri'e type not determined



)" dri'e type determined

Bit ) indicates dri'e multirate status

0" dri'e is not multirate

)" dri'e is multirate

Bit 0 indicates chan>e line detection

0" no chan>e line detection

)" chan>e line detection

;4h )42 Int )h ) "yte Disette 0 current cylinder

;!h )4; Int )h ) "yte Disette ) current cylinder

;1h )!0 Int )1h ) "yte ?ey"oard status <a>s

Bit 3, )" readin> two "yte ey"oard ID in pro>ress

Bit 1, )" last code was Frst ID character

Bit !, )" forced Cumloc on

Bit 4 indicates presence of )0)*)0 ey ey"oard

0" present

)" not present

Bit indicates ri>ht alt ey acti'e

0" not acti'e

)" acti'e

Bit indicates ri>ht control ey acti'e

0" not acti'e

)" acti'e

Bit ), )" last scancode was 70h

Bit 0, )" last scancode was 7)h

;3h )!) Int )1h ) "yte ?ey"oard status <a>s 4

Bit 3, )" ey"oard transmit error

Bit 1, )" 7D update in pro>ress

Bit !, )" resend code recei'ed

Bit 4, )" acnowled>e code recei'ed

Bit , )" reser'ed

Bit indicates -apsoc 7D state

0" -apsoc 7D o$

)" -apsoc 7D on

Bit ) indicates Cumoc 7D state

0" Cumoc 7D o$

)" Cumoc 7D on

Bit 0 indicates Scrolloc 7D state

0" Scrolloc 7D o$

)" Scrolloc 7D on

;2h )!!

4 "ytes Se>ment:O$set address of user wait <a> pointer

;-h )!;

4 "ytes Hser wait count

A0h )10

) "yte Hser wait <a>

Bit 3, )" wait time has elapsed

Bit 1) not used

Bit 0 indicates wait pro>ress

0" no wait in pro>ress

)" wait in pro>ress

A)h )13

3 "ytes ocal area networ +AC/ "ytes

A2h )3)

4 "ytesSe>ment:O$set address of 'ideo parameter control"loc

A-h ;

12 "ytes eser'ed

(0h !!

)1 "ytes Intraapplications communications area

BIOS Data Area(Detailed)

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Transcript of BIOS Data Area(Detailed)