Computer History 101: The Development Of The PC

Birth Of The Personal Computer

The fourth generation of the modern computer includes those that incorporate microprocessors in their designs.Of course, part of this fourth generation of computers is the personal computer, which itself was made possible by the advent of low-cost microprocessors and memory.

Birth of the Personal Computer

In 1973, some of the first microcomputer kits based on the 8008 chip were developed. These kits were little more than demonstration tools and didn’t do much except blink lights. In April 1974, Intel introduced the 8080 microprocessor, which was 10 times faster than the earlier 8008 chip and addressed 64 KB of memory. This was the breakthrough that the personal computer industry had been waiting for.

A company called MITS introduced the Altair 8800 kit in a cover story in the January 1975 issue of Popular Electronics. The Altair kit, considered by many to be the first personal computer, included an 8080 processor, a power supply, a front panel with a large number of lights, and 256 bytes (not kilobytes) of memory. The kit sold for $395 and had to be assembled. Assembly back then meant you got out your soldering iron to actually finish the circuit boards—not like today, where you can assemble a system of premade components with nothing more than a screwdriver.

Ed Roberts, The "Father Of The Personal Computer"

Micro Instrumentation and Telemetry Systems was the original name of the company founded in 1969 by Ed Roberts and several associates to manufacture and sell instruments and transmitters for model rockets. Ed Roberts became the sole owner in the early 1970s, after which he designed the Altair. By January 1975, when the Altair was introduced, the company was called MITS, Inc., which then stood for nothing more than the name of the company. In 1977, Roberts sold MITS to Pertec, moved to Georgia, went to medical school, and became a practicing physician. Considered by many to be the “father of the personal computer,” Roberts passed away in 2010 after a long bout with pneumonia.

The Altair included an open architecture system bus later called the S-100 bus, so named because it became an industry standard and had 100 pins per slot. The S-100 bus was widely adopted by other computers that were similar to the Altair, such as the IMSAI 8080, which was featured in the movie WarGames. The S-100 bus open architecture meant that anybody could develop boards to fit in these slots and interface to the system, and it ensured a high level of cross-compatibility between different boards and systems.The popularity of 8080 processor–based systems inspired software companies to write programs, including the CP/M (control program for microprocessors) OS and the first version of the Microsoft BASIC (Beginners All-purpose Symbolic Instruction Code) programming language.

IBM's First Personal Computer (But Not PC Compatible)

IBM introduced what can be called its first personal computer in 1975.The Model 5100 had 16 KB of memory, a built-in 16-line-by-64-character display, a built-in BASIC language interpreter, and a built-in DC-300 cartridge tape drive for storage. The system’s $8975 price placed it out of the mainstream personal computer marketplace, which was dominated by experimenters (affectionately referred to as hackers) who built low-cost kits ($500 or so) as a hobby. Obviously, the IBM system was not in competition for this low-cost market and did not sell as well by comparison.

The Model 5100 was succeeded by the 5110 and 5120 before IBM introduced what we know as the IBM Personal Computer (Model 5150). Although the 5100 series preceded the IBM PC, the older systems and the 5150 IBM PC had nothing in common. The PC that IBM turned out was more closely related to the IBM System/23 DataMaster, an office computer system introduced in 1980.In fact, many of the engineers who developed the IBM PC had originally worked on the DataMaster.

Apple's First Personal Computer (But Not Macintosh Compatible)

In 1976, a new company called Apple Computer introduced the Apple I, which originally sold for $666.66. The selling price was an arbitrary number selected by one of Apple’s cofounders, Steve Jobs. This system consisted of a main circuit board screwed to a piece of plywood; a case and power supply were not included. Only a few of these computers were made, and they reportedly have sold to collectors for more than $20 000. The Apple II, introduced in 1977, helped set the standard for nearly all the important microcomputers to follow, including the IBM PC.

The microcomputer world was dominated in 1980 by two types of computer systems. One type, the Apple II, claimed a large following of loyal users and a gigantic software base that was growing at a fantastic rate. The other type, CP/M systems, consisted not of a single system but of all the many systems that evolved from the original MITS Altair. These systems were compatible with one another and were distinguished by their use of the CP/M OS and expansion slots, which followed the S-100 standard. All these systems were built by a variety of companies and sold under various names. For the most part, however, these systems used the same software and plug-in hardware.It is interesting to note that none of these systems was PC compatible or Macintosh compatible, the two primary standards in place today.

A new competitor looming on the horizon was able to see that to be successful, a personal computer needed to have an open architecture, slots for expansion, a modular design, and healthy support from both hardware and software companies other than the original manufacturer of the system. This competitor turned out to be IBM, which was quite surprising at the time because IBM was not known for systems with these open-architecture attributes. IBM, in essence, became more like the early Apple, whereas Apple became like everybody expected IBM to be. The open architecture of the forthcoming IBM PC and the closed architecture of the forthcoming Macintosh caused a complete turnaround in the industry.

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  • raclimja

    i still have my pentium 2 gathering dust on my closet

    improvements in technology is AMAZING
  • grooveboss
    ^ dweeb alert
  • Pyree
    The article contains no post-PC era nonsense! Just the way it should be.
  • dogman_1234
    I liked it. Love history; and the history of computerized technology. Can't wait to see the next 50 years.
  • mayankleoboy1
    just one question:

    why this article? in the whole wide range of PC, why this?
    you could have done the second part to the Antiliasing article.
  • cangelini
    mayankleoboy1just one question: why this article? in the whole wide range of PC, why this?you could have done the second part to the Antiliasing article.

    That's still on its way. It's very data-intensive and Don has been plugging away at it.
  • Chewie
    No mention of the Commodore in any of its forms? :(
  • SteelCity1981
    2006: Microsoft releases the long-awaited Windows Vista to business users. The PC OEM and consumer market releases would follow in early 2007:

    It should really read.

    2006: Microsoft releases the long-awaited Windows Vista to business users. The PC OEM and consumer market releases would follow in early 2007 and the vast majority of people quickly downgraded back to Windows XP:

  • madsbs
    Pics or it didn't happen!

    Where are the illustrations for this rather interesting piece?
  • jj463rd
    One thing that I disliked about the Timeline of Computer Advancements was leaving out Douglas Englebart and the Mother of All Demos in 1968(if you don't know about him you know very little about computer history )and giving accolades instead to Xerox.
  • Firehead2k
    I also missed the Commodore line of pcs
  • Mark Heath
    Nice read, reminded me to read up a bit more history on Apple, I knew jobs left for a while, but only found out today that he's apparently taken LSD and went Hindu after a trip to India. Yes, *apparently*, go look it up :)
  • molo9000
    he system’s $8975 price placed it out of the mainstream personal computer marketplace

    That's a mild understatement. In 1975 you could buy a brand new V8 powered Ford Mustang for $4000.

    The move to a PC-based architecture is without a doubt the smartest move Apple has made in years—besides reducing Apple’s component costs, it allows Macs to finally perform on par with PCs.

    Eh? Apple had to move to Intel because PowerPC was going downhill in 2006, but a there was a time when PowerPC chips were faster than Intel chips.

    I would say it is a safe bet that PC-compatible systems will continue to dominate the personal computer marketplace for the foreseeable future.

    That's a bold statement considering that the next version of Windows is going to be ARM compatible.
    The personal computer isn't going anywhere, but we might see the end of x86 dominance soon.
  • Krnt
    No Fusion and no ARM? WTF?!
  • nforce4max
    Where is Xerox and their contributions? They made the GUI and the mouse as well ethernet networking so it isn't like they were vaporware.
  • leandrodafontoura
    This article is misleading a little bit. Apple computers, before the change to Intel processors, used IBM processors, wich were significantly superior to Intel best solution
  • kilo_17
    So does this mean without IBM, the PC would be way different than what it is today?
  • ta152h
    Quite a few mistakes, but the most glaring is the overstatement with regards to the Apple II. What standard did it set? Expansion slots were on other machines, although IBM certainly saw this on the Apple. Of course, you didn't have the problems where certain card wouldn't work in certain slots (except in VERY rare cases), whereas Apple was much more rigid. The weird video where you couldn't put certain colors next to other colors were certainly never copied. The 6502 was a dead end, and Apple's next computer went to the 68K. The design where the keyboard was part of the computer was not copied by IBM,and in any case had been predated.

    Also, it was NOT a huge standard. The TRS-80 was at least as important in 1977 and the next few years, and was the best selling computer before the IBM PC came out. Also, don't forget Atari, which was also out there with the Atari 400 and Atari 800, and had very powerful video acceleration technology.

    It's not the Apple II wasn't selling, but it wasn't a predominate standard as stated, and had very strong competition. It was basically overpriced junk, with a slow, very annoying processor (which is the basis for ARM's instruction set), annoying video modes, weird floppy disk technology, and a price excessive for what the machine was.

    Also, the Pentium II was not basically a Pentium Pro with MMX. It had much more important changes (in retrospect, since MMX didn't matter much). For one, the Pentium Pro ran 16-bit code very poorly, and it was obscenely expensive because of the L2 cache on the processor package. They slowed down the L2 cache with external chips (for the Klamath, Deschutes, and Katmai), but doubled the L1 cache. This cut costs dramatically. Also, the Pentium II was able to run 16-bit code better than the Pentium for the first time.
  • jc5427
    No mention of Unix/Linux?
  • jcknouse
    They still make that book?

    I think I have the 2nd Ed of that book at home, with ISA ports listed in it.

    A free copy would mean I have one that's up-to-date. lolz
  • TeraMedia
    My father still has a working MITS altair. The disk drives are a bit flakey, and I don't think the punch tape drive has been used since the 70s, but it packs a full 64KB sRAM, and has switches on the front by which you can actually toggle in the machine code if you want. Working in 64 KB of program and data space is challenging to say the least. It runs a variant of BASIC written by William Gates, whoever that is.
  • cangelini
    madsbsPics or it didn't happen!Where are the illustrations for this rather interesting piece?

    Alas, we weren't able to add artwork to the story as it appears in the book; believe me, I wanted to as well :)
  • JohnA
    TA152HQuite a few mistakes....

    Yeah, I was going to add similar. One thing they also forgot was LIM, Lotus/Intel/Microsoft. Before MS put out the Office suit, and IBM headed down it's lonesome OS/2 trail (wow, not even a mention of OS/2 ???), Lotus played a role in the early evolution.

    What made the PC standard was open hardware, AND software the masses could use.
  • HistoryBuff44
    Im curious, why no mention of Konrad Zuse's Z1 machine he built in the late 30's and early 40's?