PC System Design Guide

The PC System Design Guide is a series of hardware design requirements and recommendations for IBM PC compatible personal computers, compiled by Microsoft and Intel Corporation during 1997–2001. They were aimed at helping manufacturers provide hardware that made the best use of the capabilities of the Microsoft Windows operating system, and to simplify setup and use of such computers.
Every part of a standard computer and the most common kinds of peripheral devices are defined with specific requirements. Systems and devices that meet the specification should be automatically recognized and configured by the operating system.

Versions

Four versions of the PC System Design Guide were released. In PC-97, a distinction was made between the requirements of a Basic PC, a Workstation PC and an Entertainment PC. In PC-98, the Mobile PC was added as a category. In PC 2001, the Entertainment PC was dropped.

Version	Date
PC-97	February 9, 1998
PC-98	December 31, 1998
PC-99	July 14, 1999
PC 2001	November 2, 2000

PC-97

Required:

120 MHz Pentium, MIPS R4x00, Digital Alpha 21064 or IBM PowerPC architecture
16 MB RAM

Initial version.

Introduced color code for PS/2 keyboard and PS/2 mouse connectors
PC-98

Aimed at systems to be used with Windows 98 or Windows 2000. Required:

200 MHz Pentium processor with MMX technology
256 KB L2 cache
32 MB RAM
ACPI 1.0
Fast BIOS power-up
BIOS Y2K compliance
PXE preboot environment

It was published as.

PC-99

Required:

300 MHz CPU
64 MB RAM
USB
Comprehensive color-coding scheme for ports and connectors

Strongly discouraged:

Non plug-and-play hardware
ISA slots

It was published as.

PC 2001

Required:

667 MHz CPU
64 MB RAM

Final version. First to require IO-APICs to be enabled on all desktop systems. Places a greatly increased emphasis on legacy-reduced and legacy-free systems. Some "legacy" items such as ISA expansion slots and device dependence on MS-DOS are forbidden entirely, while others are merely strongly discouraged.
PC 2001 removes compatibility for the A20 line: "If A20M# generation logic is still present in the system, this logic must be
terminated such that software writes to I/O port 92, bit 1, do not result in A20M# being asserted to the processor."

Color-coding scheme for connectors and ports

Perhaps the most end-user visible and lasting impact of PC 99 was that it introduced a color code for the various standard types of plugs and connectors used on PCs. As many of the connectors look very similar, particularly to a novice PC user, this made it far easier for people to connect peripherals to the correct ports on a PC. This color code was gradually adopted by almost all PC and motherboard manufacturers. Some of the color codes have also been widely adopted by peripheral manufacturers.