Chapter 3
Hardware
CoreModule 740
Reference Manual
25
Note:
The shaded areas denote power or ground. The signals marked with * indicate active low.
56
ALE
Address Latch Enable – This signal is used to latch the LA23 to LA17
signals or decodes of these signals. Addresses are latched on the falling
edge of BALE. It is forced high during DMA cycles. When used with
AENx, it indicates a valid processor or DMA address.
57
GND22
Floppy Ground
58
IDE_PDDACK*
Primary DMA Channel Acknowledge – Used by the host to acknowledge
data has been accepted or data is available. Used in response to PDREQ
asserted.
59
FDD_DATA*
Floppy Read Data – Raw serial bit stream from the drive for read
operations
60
GND4
IDE Ground
61
GND23
Floppy Ground
62
IDE_IRQ14
Primary Interrupt Request 14 – Asserted by drive when it has a pending
interrupt (PIO transfer of data to or from the drive to host.)
63
FDD_HDSEL*
Floppy Head Select – Selects the side for Read/Write operations (0 = side
1, 1 = side 0)
64
IOCS16*
I/O Chip Select 16 – This signal is driven low by an I/O slave device to
indicate it is capable of performing a 16-bit I/O data transfer. This signal
is driven from a decode of the SA15 to SA0 address lines.
65
GND24
Floppy Ground
66
IDE_PDA1
Primary Disk Address 1 – Used to indicate which byte in the ATA
command block or control block is being accessed
67
FDD_DSKCHG* Floppy Disk Change – Senses the drive door is open or the diskette has
been changed since the last drive selection
68
IDE_CABLID
Cable ID – Used for slave and master negotiation and for 40 and 80 pin
IDE cable selection
69
NC
Not Connected
70
IDE_PDA0
Primary Disk Address 1 – Used to indicate which byte in the ATA
command block or control block is being accessed
71
NC
Not Connected
72
IDE_PDA2
Primary Disk Address 1 – Used to indicate which byte in the ATA
command block or control block is being accessed
73
NC
Not Connected
74
IDE_PDCS1*
Primary Chip Select Drive 1 – Used to select the host-accessible
Command Block Register for Drive 1
75
NC
Not Connected
76
IDE_PDCS3*
Primary Chip Select Drive 3 – Used to select the host-accessible
Command Block Register for Drive 3
77
NC
Not Connected
78
HDACT
Primary IDE Drive Activity LED – Used to drive an external IDE activity
LED, indicating drive activity
79
NC
Not Connected
80
GND5
IDE Ground
Table 3-5. Utility 2 Interface Pin Signals (J4) (Continued)
