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IBM introduced the PC, its first personal computer in August 1981.
As I heard on the radio over the weekend, a fully configured system
(including 64 KB RAM, two floppies, monitor, and printer) cost about
$4,500. Just imagine what you could buy for that amount today!
Standards
For better or worse, our biggest debt to the IBM PC was creating a
set of standards that would shape the personal computing industry, a
field which had already been around for five years.
Prior to the PC, personal computers might be based on the 6502,
6809, Z80, or 8080, 8-bit processors capable of supporting 64 KB of
memory. The new processors just coming into their own were the Motorola
68000, which IBM considered using, and the Intel 8086/8088, which IBM
adopted. Today about 95% of all personal computers sold use processors
descended from the Intel 8086.
Prior to the IBM PC, some computers used 8" floppies, and most
personal machines used 5.25" floppies - each computer with its own disk
format. One of the leading utilities for CP/M machines allowed them to
read disks formatted for other CP/M computers. There was no
compatibility between the Apple II, Atari, Commodore, TRS-80, and other
non-CP/M brands. With the IBM PC, we had a standard 5.25" format, an
ancestor of the format used on 3.5" floppy drives on today's PCs.
Prior to the PC, some computers had 24 lines of text, others 25.
Some had 40 characters per line, others 64, and still others 80. Some
even supported 132 characters - or as few as 22. With the IBM PC, the
standard text format became 25 lines of 80 characters - or 40
characters on color displays.
The original IBM PC supported dual monitor work. You could have a
monochrome text display and a color screen by using a monochrome
display adapter and a color graphics adapter. The text display didn't
support graphics, and the color display provided very low resolution
text and graphics - 320 x 200 pixels.
Prior to the PC, there were a few competing standards for serial and
parallel ports. Except for Apple, almost everyone has followed IBM's
lead in that regard.
Prior to the PC, personal computers either ran a proprietary
operating system or CP/M. Within a few years of the PC's introduction,
the vast majority of computers ran MS-DOS, the ancestor of Microsoft
Windows.
Microsoft has ported Windows NT to non-Intel hardware, specifically
the Alpha and PowerPC processors, but it never made a dent outside of
the Wintel market.
Competing Standards
Some companies tried to one-up IBM by offering higher density
floppies, higher resolution graphics, better keyboard layouts, support
for more than 640 KB of memory, industry standard busses, the 16-bit
8086 CPU, and some even had a second processor such as a Z80, 8080, or
8085 that could run CP/M.
The
Zenith Z-100 and Texas Instruments Professional Computer are
distant memories. They tried to offer a better solution, but being
different doomed them. The same thing happened to NEC's Advanced Personal
Computer, which was one of the few DOS machines to use 8" floppies.
Doomed.
Clones succeeded initially based on how compatible they were with
the standard IBM created. It didn't take long for the IBM PC, its
descendants, and other DOS boxes to dominate the personal computing
industry, shoving Atari, Commodore, and so many other brands to the
sides and eventually out of the picture.
DOS and Windows
The IBM PC didn't ship with an operating system: The buyer could
choose PC-DOS, CP/M-86, or the UCSD p-system. PC-DOS (IBM's name for
MS-DOS) was cheaper; it won.
The next OS battle was between OS/2, a joint development of
Microsoft and IBM, and Windows. Windows won and is the dominant
operating system on the market today.
The second most popular OS on PC hardware is Linux, an operating
system derived from Unix. It's very stable, very powerful, and has
maybe 5% of the desktop computer market. On the other hand, Linux has
become a leading server platform, where it apparently runs 20-30% of
all servers on the Internet.
The other significant minority OS is the Mac OS, which is now split
into "classic" and OS X. The classic Mac OS only runs on Macintosh
computers and a handful of licensed
clones. Although some have ported Darwin (part of OS X) to the
PC architecture, Apple only sells OS X for G3- and G4-based
Macs.
Between them, all of the minority platforms control about 10% of the
personal computer market vs. about 90% for Windows.
Graphics Standards
The original monochrome display adapter supported a very high
resolution screen, but it didn't do graphics. Hercules invented the
Hercules
Graphics Adapter, which allowed high resolution (720 x 350)
graphics on IBM's monochrome display. HGA became a popular business
standard.
The color graphics adapter supported 320 x 200 pixels with up to 4
colors. CGA eventually gave way to EGA, with 640 x 350 resolution,
which later gave way to VGA (640 x 480). Today's PC monitors are
descended from the VGA standard, and for the past several years Apple
has adopted the same video port and standards to make it easier for Mac
owners to buy monitors. (Let's not get started on Apple's digital video
port....)
Expansion
The original IBM PC didn't even have a hard drive option. It had two
bays for full-height (about 3" high!) 5.25" floppy drives, five
expansion slots, and enough sockets on the motherboard to support 256
KB of memory. The 8-bit expansion slots ran at the same 4.77 MHz as the
CPU, which has a 16-bit processor designed to run on an 8-bit bus.
(Sound familiar? Several Road
Apples did the same kind of thing, running a 32-bit CPU on a 16-bit
bus.)
IBM expanded that to a 16-bit bus with the IBM AT (for Advanced
Technology) in 1984, a machine that also supported a high capacity 1.2
MB floppy disk. The 16-bit AT slots ran at the same 6 MHz speed as
the CPU. As clones began to push the envelope, the question of bus
speed vs. CPU speed became important, because a card that ran fine at 6
or 8 MHz might not work reliably at 10 or 12 MHz. Eventually the
industry adopted 8 MHz as an ad hoc standard.
IBM tried to differentiate itself with Micro Channel
Architecture (MCA), a new bus that never caught on with the PC
industry. The rest of the industry created the
EISA standard (Extended Industry Standard Architecture), which was
later replaced by PCI (Peripheral
Component Interconnect). That's the standard both Macs and PCs support
today.
The first hard drives needed controller cards, but over the years
manufacturers started building some of those electronics into the drive
itself, eventually the IDE standard. IDE
gave way to EIDE and ATA, followed by the Ultra/ATA standards used on
PCs and Macs today.
In the end, we ended up with Macs and PCs using mostly the same
parts, not counting the main processor, as Apple adopted standard parts
to keep costs down.
The IBM PC Legacy
More than anything else, IBM legitimized personal computers as
business machines. The standard architecture IBM pioneered using
off-the-shelf components allowed Microsoft to become the behemoth it is
today. And the sheer size of the Wintel industry has made standard
components readily affordable, allowing anyone to build their own clone
and Apple to reduce the cost of building Macs by using many of those
same components.
The great irony is that Apple, then a dominant player in the
personal computing industry, welcomed IBM in 1981. The IBM PC lead to
the marginalization of Apple, and Microsoft managed to turn IBM into a
bit player in the PC industry. Today IBM and Apple are partners in
certain areas, particularly the PowerPC processor.
Personal computers have gone from an expensive hobby to something
most households seem to have and businesses can't imagine being
without. That's the biggest part of the IBM PC legacy.
Dan Knight has been using Macs since 1986,
sold Macs for several years, supported them for many more years, and
has been publishing Low End Mac since April 1997. If you find Dan's articles helpful, please consider making a donation to his tip jar.
Links for the Day
Mac of the Day: DayStar Genesis, introduced 1995.10.30. The first 'Mac' with multiple processors, technology Daystar licensed to Apple.
