CHAPTER 3
I/O Features
16 Internal Hard Disk Drive
This chapter describes both the built-in I/O devices and the interfaces for external I/O
devices. Like the earlier chapters, it emphasizes the similarities and differences between
the PowerBook 520 and 540 computers and other PowerBook models.
This chapter describes the following built-in devices and I/O ports:
■ internal hard disk drive
■ internal floppy disk drive
■ built-in trackpad
■ built-in keyboard
■ built-in flat panel display
■ external video port
■ serial port
■ SCSI port
■ Ethernet port
■ Apple Desktop Bus
(ADB) port
■ sound system
Internal Hard Disk Drive 3
The PowerBook 520 and 540 computers have an internal 2.5-inch hard disk drive
connected to an internal SCSI connector. The following information is provided as a
general guideline and is based on the specifications for Apple’s 2.5-inch, 240 MB hard
disk drive.
Hard Disk Power Budget 3
The hard disk drive operates on 5 VDC ± 5 percent. The maximum ripple voltage the
drive must tolerate is 100 mV peak to peak at any frequency from DC to 10 MHz.
Table 3-1 shows the maximum and average current drain and power consumption for
various operating modes of the hard disk drive. These limits include 1 kΩ pull-up
terminator resistors on all signal lines. All mean specifications are RMS (root-mean-
square) values.
IMPORTANT
The hard disk drive must not exceed the maximum
power specifications given in Table 3-1. ▲
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