Format of Extended BIOS Data Area (PhoenixBIOS 4.0) (Cont.)
MEM 0040h:0089h U - VIDEO (MCGA/VGA) - MODE-SET OPTION CONTROL
Size: BYTE
See Also: MEM 0040h:0087h,MEM 0040h:0088h
Bitfields for Video mode-set option control:
Bit(s) Description (Table M027)
7,4 requested scan lines
0 0 350-line mode requested
0 1 400-line mode at next mode set
1 0 200-line mode requested
1 1 reserved
Note: Apparently VGA BIOS mode set disregards bit 7 and uses
byte 40h:88h to determine 200/350 selection when bit 4
is zero. Presumably bit 7 is a convenience for other
purposes. Bit 7 is reset to zero after the mode set.
6 display switching enabled
5 reserved
4 if set: use 400-line mode at next mode set
if clear: [VGA] emulate EGA at next mode set
[MCGA] emulate CGA, digital monitor, 200 lines, 8x8 text
Note: this bit is set by the video mode set on VGA, unchanged on MCGA
3 default palette loading DISabled at mode set
2 mono display
1 gray scale summing enabled
0 [VGA] =1 if VGA active, =0 if not
[MCGA] reserved, zero
Note: the Tseng ET4000 BIOS v3.00 uses bits 6-4 of 88h and bits 6-5 of 89h
to specify graphics-mode refresh rates as follows
88h/6 640x480: 1 for 72Hz,0 for 60Hz
88h/5+89h/6 800x600: 00 60Hz
01 56Hz
11 72Hz
88h/4+89h/5 1024x768: 00 interlaced
01 60Hz
10 72Hz???
11 70Hz
--------V-M0040008A--------------------------
MEM 0040h:008Ah U - VIDEO (MCGA/VGA) - INDEX INTO DISPLAY COMBINATION CODE TBL
Size: BYTE
See Also: INT 10/AX=1A00h,#M039
--------*-M0040008B--------------------------
MEM 0040h:008Bh - PC, PCjr, PC/XT 11/8/82, Convertible - RESERVED
Size: 11 BYTEs
--------B-M0040008B--------------------------
MEM 0040h:008Bh - DISKETTE MEDIA CONTROL
Size: BYTE
Bitfields for diskette media control:
Bit(s) Description (Table M028)
7-6 last data rate set by controller
00=500kbps, 01=300kbps, 10=250kbps, 11=1Mbps
5-4 last diskette drive step rate selected
00=0Ch, 01=0Dh, 10=0Eh, 11=0Ah
3-2 {data rate at start of operation}
1-0 reserved
Note: EHD BIOS sets this byte to 01h and never reads it back
--------B-M0040008C--------------------------
MEM 0040h:008Ch - FIXED DISK - CONTROLLER STATUS [not XT]
Size: BYTE
See Also: MEM 0040h:008Dh,MEM 0040h:008Eh
--------B-M0040008D--------------------------
MEM 0040h:008Dh - FIXED DISK - CONTROLLER ERROR STATUS [not XT]
Size: BYTE
See Also: MEM 0040h:008Ch,MEM 0040h:008Eh
--------B-M0040008E--------------------------
MEM 0040h:008Eh - FIXED DISK - INTERRUPT CONTROL [not XT]
Size: BYTE
Note: cleared to 00h at start of disk operation, set to FFh by IRQ14
handler when hard disk controller completes command
See Also: MEM 0040h:008Ch,MEM 0040h:008Dh,MEM 0040h:008Fh
--------B-M0040008F--------------------------
MEM 0040h:008Fh U - DISKETTE CONTROLLER INFORMATION [not XT]
Size: BYTE
See Also: MEM 0040h:008Ch,MEM 0040h:008Dh,MEM 0040h:008Eh
Bitfields for diskette controller information:
Bit(s) Description (Table M029)
7 reserved
6 =1 drive 1 determined
5 =1 drive 1 is multi-rate, valid if drive determined
4 =1 drive 1 supports 80 tracks, always valid
3 reserved
2 =1 drive 0 determined
1 =1 drive 0 is multi-rate, valid if drive determined
0 =1 drive 0 supports 80 tracks, always valid
Note: EHD BIOS sets this byte to 01h and never alters it again
--------B-M00400090--------------------------
MEM 0040h:0090h - DISKETTE DRIVE 0 MEDIA STATE
Size: BYTE
See Also: MEM 0040h:0091h
Bitfields for diskette drive media state:
Bit(s) Description (Table M030)
7-6 data rate
00=500kbps, 01=300kbps, 10=250kbps, 11=1Mbps
5 double stepping required (e.g. 360kB in 1.2MB)
4 media type established
3 drive capable of supporting 4MB media
2-0 on exit from BIOS, contains
000 trying 360kB in 360kB
001 trying 360kB in 1.2MB
010 trying 1.2MB in 1.2MB
011 360kB in 360kB established
100 360kB in 1.2MB established
101 1.2MB in 1.2MB established
110 reserved
111 all other formats/drives
See Also: #M031,#M032
--------B-M00400091--------------------------
MEM 0040h:0091h - DISKETTE DRIVE 1 MEDIA STATE
Size: BYTE
See Also: MEM 0040h:0090h,#M030
--------B-M00400092--------------------------
MEM 0040h:0092h U - DISKETTE DRIVE 0 MEDIA STATE AT START OF OPERATION
Size: BYTE
Note: officially "Drive 2 media state"
See Also: MEM 0040h:0093h"DRIVE 1"
Bitfields for diskette drive 0 media state at start of operation:
Bit(s) Description (Table M031)
7-3 (see #M030)
2 multiple data rate capability determined
1 multiple data rate capability
0 =1 if drive has 80 tracks, =0 if 40 tracks
See Also: #M030,#M032
--------d-M00400092--------------------------
MEM 0040h:0092h - Olivetti Quaderno - HARD DISK POWERDOWN COUNTDOWN CLOCK TICKS
Size: BYTE
Note: hard disk is turned off when counter reaches zero
--------B-M00400093--------------------------
MEM 0040h:0093h U - DISKETTE DRIVE 1 MEDIA STATE AT START OF OPERATION
Size: BYTE
Note: officially "Drive 3 media state"
See Also: MEM 0040h:0092h"DRIVE 0"
Bitfields for diskette drive 1 media state at start of operation:
Bit(s) Description (Table M032)
7-3 (see #M030)
2 multiple data rate capability determined
1 multiple data rate capability
0 =1 if drive has 80 tracks, =0 if 40 tracks
--HP 100LX/200LX--
display control status
0 =1 if DISPCTL -K
1 =1 if DISPCTL -C
--------B-M00400094--------------------------
MEM 0040h:0094h - DISKETTE DRIVE 0 CURRENT TRACK NUMBER
Size: BYTE
See Also: MEM 0040h:0095h
--------B-M00400095--------------------------
MEM 0040h:0095h - DISKETTE DRIVE 1 CURRENT TRACK NUMBER
Size: BYTE
See Also: MEM 0040h:0094h
--------K-M00400096--------------------------
MEM 0040h:0096h - KEYBOARD STATUS BYTE 1
Size: BYTE
See Also: MEM 0040h:0097h,INT 16/AH=11h
Bitfields for keyboard status byte 1:
Bit(s) Description (Table M033)
7 =1 read-ID in progress
6 =1 last code read was first of two ID codes
5 =1 force Num Lock if read-ID and enhanced keyboard
4 =1 enhanced keyboard installed
3 =1 Right Alt pressed
2 =1 Right Ctrl pressed
1 =1 last code read was E0h
0 =1 last code read was E1h
See Also: #M034,#M010
--------K-M00400097--------------------------
MEM 0040h:0097h - KEYBOARD STATUS BYTE 2
Size: BYTE
See Also: MEM 0040h:0096h,INT 16/AH=11h
Bitfields for keyboard status byte 2:
Bit(s) Description (Table M034)
7 =1 keyboard transmit error flag
6 =1 LED update in progress
5 =1 RESEND received from keyboard
4 =1 ACK received from keyboard
3 reserved, must be zero
2 Caps Lock LED
1 Num Lock LED
0 Scroll Lock LED
See Also: #M033,#M010
--------B-M00400098--------------------------
MEM 0040h:0098h - TIMER2 (AT, PS exc Mod 30) - PTR TO USER WAIT-COMPLETE FLAG
Size: DWORD
Note: (see INT 15/AX=8300h)
See Also: MEM 0040h:009Ch,INT 15/AH=83h,INT 15/AH=86h
--------B-M0040009C--------------------------
MEM 0040h:009Ch - TIMER2 (AT, PS exc Mod 30) - USER WAIT COUNT IN MICROSECONDS
Size: DWORD
See Also: MEM 0040h:0098h,MEM 0040h:00A0h,INT 15/AH=83h,INT 15/AH=86h
--------V-M0040009F--------------------------
MEM 0040h:009Fh - HP 100LX/200LX - VIDEO ZOOM MODE
Size: BYTE
(Table M035)
Values for HP 100LX/200LX video zoom mode: