IBM PC 100, Technical Manual

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Chapter 2. Connectors and Jumpers
Hard Disk Drive Connectors (Primary/Secondary)
PC 100 and PC 300 computers have two EIDE connectors for attaching IDE devices (such as hard disk
drives and CD-ROM drives). The signals that are provided by these connectors include the 16-bit data
bus, address lines
A0
to
A2
,
IRQ
, and
-IO CS16
. These signals operate in the same way as the normal
I/O-channel signals. The interface to the hard disk drive complies with
ANSI ATA-2 (AT Attachment).
The address decode logic for the hard disk drive is on the system board. On a valid decode of
A0
through
A15
equal to 01F0h through 01F7h,
-HFCS0
(0170h through 0177h,
-HFCS2
for a secondary hard disk
drive) goes active. On a valid decode of
A0
through
A15
equal to 03F6h through 03F7h,
-HFCS1
(0376h
through 0377h,
-HFCS3
for a secondary hard disk drive) goes active.
The following figure shows the signal and pin assignments for the EIDE connectors.
Figure 14. EIDE Connector Signal and Pin Assignments
Pin Signal Pin Signal
1 -RESET 2 Ground
3 Data bus bit 7 4 Data bus bit 8
5 Data bus bit 6 6 Data bus bit 9
7 Data bus bit 5 8 Data bus bit 10
9 Data bus bit 4 10 Data bus bit 11
11 Data bus bit 3 12 Data bus bit 12
13 Data bus bit 2 14 Data bus bit 13
15 Data bus bit 1 16 Data bus bit 14
17 Data bus bit 0 18 Data bus bit 15
19 Ground 20 Key (Reserved)
21 DRQ0/DRQ1 22 Ground
23 -IO Write 24 Ground
25 -IO Read 26 Ground
27 IO Channel Ready 28 VCC pullup
29 DACK0/DACK1 30 Ground
31 IRQ14/IRQ15 32 VCC pullup
33 Device address A1 34 Ground
35 Device address A0 36 Device address A2
37 -HFCS0 38 -HFCS1
39 Activity # 40 Ground
Chapter 2. Connectors and Jumpers
17