Mass Storage Devices And Controllers; Power Supplies; Fans - Digital Equipment MicroVAX 3600 Operation

1.3.1.4 Mass Storage Devices and Controllers
Mass storage devices record data on magnetic media. The data recorded is
not lost when you turn off the system, but can be altered or erased if you
record over the data. Use mass storage devices to store data and software
permanently. When the data or software is needed, the CPU copies it from
the mass storage device into main memory. The two primary types of mass
storage devices are fixed disks and devices with removable media, such as
tape cartridges.
Fixed- Disk Drives
Fixed-disk drives are permanently installed in your system. They provide
large-capacity storage for software and data files, as well as rapid access to
the data by the CPU. Your system may have multiple fixed-disk drives.
Devices with Removable Media
Devices with removable media, such as disk packs, tape cartridges, and tapes,
are used as both input and output devices. You use them as input devices
when you install software or copy data to your system. Tape cartridges are
the primary load media for software. You use these devices as output devices
when you copy software or data from your system. You can copy individual
files or programs, or you can copy (back up) the contents of an entire fixed
disk. Tapes and disk packs are commonly used to archive data from systems.
Mass Storage Controllers
All mass storage devices require a controller, a separate module that controls
activity between the CPU and the mass storage devices. The controller for
the fixed-disk drives (the KDA50) and the controller for the TK70 tape drive
(the TQK70) are installed to the left of other modules in the card cage.
1.3.1.5 Power Supplies
The system has two power supplies. The primary power supply provides
power to modules installed in slots 1-6, one or two mass storage devices (the
TK70 tape drive and fixed disk 1, if present), and the two fans. The second
power supply provides power for modules in slots 7-12 and fixed disk 0, if
present.
1.3.1.6 Fans
Two fans located near the bottom of the system draw in air from the top of
the system and pull it down through the modules and out the bottom. The
speed of the fans varies, depending on the surrounding room temperature.
To reduce the load on the fans, keep the system away from heat sources.
System Overview 1-25