IBM 770 System Board, Diskette Drive Type Byte Hex 010 This byte indicates the type, Bits, Hard

Diskette Drive Type Byte (Hex 010): This byte indicates the type

of the	installed	diskette	drive.
Bit	Drive	Type
7–4	Diskette drive		type
3–0	Reserved

Figure 2-21. Diskette Drive Type Byte (Hex 010)

Bits 7–4These bits indicate the diskette drive type.

Bits

7–4

Description

0

1

1

0

Diskette

drive

(2.88MB)

0

1

0 0

Diskette

drive

(1.44MB)

Note: Combinations not shown are reserved.

Figure

2-22. Diskette

Drive

Type

Bits

7–4

Bits

3–0

These

bits

are

reserved.

Hard

Disk

Drive

Type

Byte (Hex 011): This byte defines the type

of

hard

disk

drive

installed. Hex

00

indicates

that no hard disk drive

is

installed.

Bit

Drive

Type

7–4

Hard disk drive type 2

3–0

Hard disk drive type 3

Figure

2-23. Hard

Disk

Type

Byte

(Hex

011)

Bit

7–4

Description

0

0 0

0

No

drive

installed

for hard

disk

drive

2

1

1

1

1

Use CMOS 1BH for hard disk drive 2

Figure

2-24. Hard

Disk

Drive

Type

2

(Bits 7–4)

Bit

3–0

Description

0

0 0

0

No

drive

installed

for hard

disk

drive

3

1

1

1

1

Use

CMOS

1CH

for

hard

disk

drive

3

Figure 2-25. Hard Disk Drive Type 3 (Bits 3–0)

2-26 System Board