Specifications

Chapter 3 Hardware
LittleBoard 800 Reference Manual 35
Pin # Signal Description
23 PDIOW* Primary I/O Read/Write Strobe – Strobe signal for write functions. Negative
edge enables data from a register or data port of the drive onto the host data bus.
Positive edge latches data at the host.
24 GND Ground
25 PDIOR*
Primary I/O Read/Write Strobe – Strobe signal for read functions. Negative
edge enables data from a register or data port of the drive onto the host data bus.
Positive edge latches data at the host.
26 GND Ground
27 PDIORDY Primary I/O Channel Ready – When negated extends the host transfer cycle of
any host register access when the drive is not ready to respond to a data transfer
request. High impedance if asserted.
28 NC Not connected
29 PDACK*
Primary Cable Select – Used to configure IDE drives as device 0 or device 1
using a special cable
30 GND Ground
31 IRQ14
Interrupt Request 14 – Asserted by drive when it has pending interrupt (PIO
transfer of data to or from the drive to the host).
32 NC Not connected
33 PDA1
Primary ATA Disk Address – Used (0 to 2) to indicate which byte in the ATA
command block or control block is being accessed
34 PDIAG UDMA 33/66 Sense – Senses which DMA mode to use for IDE devices.
35 PDA0
Primary ATA Disk Address – Used (0 to 2) to indicate which byte in the ATA
command block or control block is being accessed
36 PDA2 Primary ATA Disk Address – Used (0 to 2) to indicate which byte in the ATA
command block or control block is being accessed
37 PDCS1 Primary Slave/Master Chip Select 1 – Used to select the host-accessible
Command Block Register.
38 PDCS3
Primary Slave/Master Chip Select 3 – Used to select the host-accessible
Command Block Register.
39 NC Not connected
40 GND Ground
Notes: The shaded area denotes power or ground. The signals marked with * = Negative true logic.
Table 3-10. Secondary IDE Interface Pin/Signal Descriptions (J7)
Pin # Signal Description
1 RESET* Low active hardware reset (RSTDRV inverted)
2 GND Ground
3 SDD7 Secondary Disk Data 7 – These signals (0 to 15) provide the disk data signals.
4 SDD8 Secondary Disk Data 8 – These signals (0 to 15) provide the disk data signals.
5 SDD6 Secondary Disk Data 6 – These signals (0 to 15) provide the disk data signals.
6 SDD9 Secondary Disk Data 9 – These signals (0 to 15) provide the disk data signals.
7 SDD5 Secondary Disk Data 5 – These signals (0 to 15) provide the disk data signals.
8 SDD10 Secondary Disk Data 10 – These signals (0 to 15) provide the disk data signals.
9 SDD4 Secondary Disk Data 4 – These signals (0 to 15) provide the disk data signals.