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Inside Linux
CPU Requirements
Linux can be installed on any IBM-compatible PC with an Intel 386, 486, or Pentium processor. All
the various processor types, such as the 80386SX, 80486SX, and 80486DX, are fully supported by
Linux. A floating-point math coprocessor is not required because Linux can emulate it via software.
NOTE
The 80486SX series and the 80386 family of processors do not have an integrated math coprocessor. If you want
ultimate performance from Linux, you should use a processor with an integrated coprocessor or ensure that your
machine has a math coprocessor installed.
Linux supports other processors, such as the Sun SPARC, Digital Alpha, MIPS, ARM, 680x0, and PPC
processors. This book does not address any machine equipped with a processor other than an Intel PC
processor. Two chip manufacturers, Advanced Micro Devices and Cyrix, make processors that mimic
Intel's 80386, 80486, and Pentium processors. These processors are fully supported by Linux.
If you are doing development work, an Intel 80486DX (or comparable clone) is the minimum
requirement. Compilers and linkers tend to soak up a lot of processor time. If you plan to run a local
SQL database, Java, a CORBA ORB, or Smalltalk, you should not consider anything less than an Intel
Pentium (or comparable) processor.
One final consideration is multiuser support. For a non-GUI machine that will support up to two
users, an Intel 80486DX should be sufficient. Beyond two users, including XFree86 support, an Intel
Pentium should be the only consideration.
Minimum (character-based Linux installation):
• IBM-compatible PC with an Intel 80386 or comparable processor from AMD or Cyrix.
Floating-point math coprocessor is recommended.
Recommended (Xfree86 GUI Linux installation):
• IBM-compatible PC with an Intel Pentium or comparable processor from AMD or Cyrix.
Memory Requirements
In this day and age of bloated operating systems, it is refreshing to discover that 2MB of Random
Access Memory (RAM) is the minimum requirement to run a true multitasking, multiuser operating
system. Of course, if you run Linux with 2MB of RAM, you will have to dedicate some hard disk space
for a swap partition. Although Linux can run on 2MB of RAM, it is recommended that you have at
least 4MB of RAM - the performance gain will be significant. The more RAM your machine has, the
better Linux performs. One catch that I have yet to mention: With fewer than 16MB of RAM, Linux
will run only in text mode. Even if you do get XFree86 to run with 8MB of RAM, your Linux system
will run painfully slow.
XFree86 is to Linux what X Windows is to UNIX. XFree86 is a clone of X Windows, providing a
windowing environment to the system. If you plan to run XFree86, be sure you have at least 16MB of
virtual memory. Notice that I say virtual memory. The total amount of virtual memory is the sum of
physical memory plus the size of the swap partition. Suppose, for example, that your machine has
12MB of RAM and you have devoted 4MB of disk space for the swap partition. This gives your Linux
system 16MB of virtual memory.
NOTE
Although it is stated that 16MB of virtual memory is sufficient to run Linux and XFree86, the proper ratio of
physical RAM to swap partition size must be considered. Linux will run sluggishly with 4MB of RAM and a 12MB
swap partition. The general rule is that physical RAM should constitute 50% of total virtual memory. Ideally
though, the swap partition size should be twice the amount of physical RAM, if you have the resources available.