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Chapter 3 Hardware
38 Reference Manual LittleBoard 550
Pin # Signal Description
33 SDA1 Secondary Disk Address 1 – One of three signals (0 – 2) used to indicate which
byte in the ATA command block or control block is being accessed.
34 SD33_66 UDMA 33/66 Sense – Used to detect the presence of an 80 conductor IDE cable
on the secondary IDE channel. Enables BIOS to sense which DMA mode to
use for IDE devices.
35 SDA0 Secondary Disk Address 0 – Refer to SDA1 on pin-33 for more information.
36 SDA2 Secondary Disk Address 2 – Refer to SDA1 on pin-33 for more information.
37 SDCS1#
Secondary Slave/Master Chip Select 1 – Used to select the host-accessible
Command Block Register.
38 SDCS3#
Secondary Slave/Master Chip Select 3 – Used to select the host-accessible
Command Block Register.
39 Reserved Reserved
40 GND Ground
Notes: The shaded area denotes power or ground. The signals marked with * = Negative true logic.