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Digital-logic ag, Cmos map – Compaq MSB900 User Manual

Page 31

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DIGITAL-LOGIC AG

MSB900/L Detailed Technical Manual V1.0

31

CMOS Map

continued...

Location

Description

0Eh

CMOS Location for Bad CMOS and Checksum Flags
Bit 7

= Flag for CMOS Lost Power

0

=

Power OK

1

=

Lost Power

Bit 6

= Flag for CMOS checksum bad

0

=

Checksum is valid

1

=

Checksum is bad

0Fh

Shutdown Code

10h

Diskette Drives

Bits 7-4 = Diskette Drive A

0000

= Not installed

0001

= Drive A = 360 kB

0010

= Drive A = 1.2MB

0011

= Drive A = 720 kB

0100

= Drive A = 1.44MB

0101

= Drive A = 2.88MB

Bits 3-0 = Diskette Drive B

0000

= Not installed

0001

= Drive B = 360 kB

0010

= Drive B = 1.2MB

0011

= Drive B = 720 kB

0100

= Drive B = 1.44MB

0101

= Drive B = 2.88MB

11h

Reserved

12h

Fixed (Hard) Drives

Bits 7-4 = Hard Drive 0, AT Type

0000

= Not installed

0001-1110 = Types 1-14
1111

= Extended drive types 16-44.

See location 19h.

Bits 3-0 = Hard Drive 1, AT Type

0000

= Not installed

0001-1110 = Types 1-14
1111

= Extended drive types 16-44.

See location 2Ah.

13h

Reserved

14h

Equipment
Bits 7-6 = Number of Diskette Drives

00

=

One diskette drive

01

=

Two diskette drives

10, 11 =

Reserved

Bits 5-4 = Primary Display Type

00

=

Adapter with option ROM

01

=

CGA in 40 column mode

10

=

CGA in 80 column mode

11

=

Monochrome

Bits 3-2 = Reserved
Bit 1

= Math Coprocessor Presence

0

=

Not installed

1

=

Installed

Bit 0

= Bootable Diskette Drive

0

=

Not installed

1

=

Installed

Continued...

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