The PC Reverse Cambrian Explosion

The Cambrian Explosion is a term from archaeology. It describes a massive increase in the diversity of life that occurred half a billion of years ago. Life on earth went from a measly few thousands of species to hundreds of millions of species in the blink of a geologic eye.

Personal Computers have what I call a "PC Reverse Cambrian Explosion" or PC-RCE. It occurred in the mid-1980s, which some might consider to be half a billion year ago. In the PC-RCE, computers went from hundreds of different designs to one: the IBM PC compatible.

In the late 1970s and very early 1980s, there were lots of designs for small computers. These included the Apple II, the Radio Shack TRS-80, the Commodore PET and CBM machines, and others. There was a great diversity of hardware and software, including processors and operating systems. Some computers had floppy disks, although most did not. Many computers used cassette tape for storage, and some had neither cassette nor floppy disk. Some computers had built-in displays, and others required that you get your own terminal.

By the mid 1980s, that diversity was gone. The IBM PC was the winning design, and the market wanted that design and only that design. (Except for a few stubborn holdouts.)

One might think that the IBM PC caused the PC-RCE, but I think it was something else.

While the IBM PC was popular, other manufacturers could not simply start making compatible machines (or "clones" as they were later called). The hardware for the IBM PC was "open" in that the connectors and buss specification were documented, and this allowed manufacturers to make accessories for IBM PCs. But the software (the operating system and importantly the ROM BIOS) was not open. While both had documentation for the interfaces, they could not be copied without running afoul of copyright law.

Other computer manufacturers could not make IBM PC clones. Their choices were limited to 1) sell non-compatible PCs in a market and did not want them, or 2) go into another business.

Yet we now have many vendors of PCs. What happened?

The first part of the PC-RCE was the weakening of the non-IBM manufacturers. Most went out of business. (Apple survived, by offering compelling alternate designs and focussing on the education market.)

The second part was Microsoft's ability to sell MS-DOS to other manufacturers. It made custom versions for non-compatible hardware by Tandy, Victor, Zenith, and others. While "compatible with MS-DOS" wasn't the same as "compatible with the IBM PC", it allowed other manufacturers to use MS-DOS.

A near-empty market allowed upstart Compaq to introduce its Compaq portable, which was the first system not made by IBM and yet compatible with the IBM PC. It showed that there was a way to build IBM PC "compatibles" legally and profitably. Compaq was successful because it offered a product not available from IBM (a portable computer) that was also compatible (it ran popular software) and used premium components and designs to justify a hefty price tag. (Several thousand dollars at the time.)

The final piece was the Phoenix BIOS. This was the technology that allowed other manufacturers to build compatible PCs at low prices. Compaq had built their own BIOS, making it compatible with the API specified in IBM's documents, but it was an expensive investment. The Phoenix BIOS was available to all manufacturers, which let Phoenix amortize the cost over a larger number of PCs, for a lower per-unit cost.

The market maintained demand for the IBM PC design, but it wasn't fussy about the manufacturer. Customers bought "IBM compatible PCs" with delight. (Especially if the price was lower than IBM's.)

Those events (weakened suppliers, an operating system, a legal path forward, and the technology to execute it) made the PC the one and only design, and killed off the remaining designs. (Again, except for Apple. And Apple came close to extinction on several occasions.)

Now, this is all nice history, but what does it have to do with us folks living today?

The PC-RCE gave us a single design for PCs. That design has evolved over the decades, and just about every piece of the original IBM PC has mutated into something else, but the marketed PCs have remained uniform. At first, IBM specified the design, with the IBM PC, the IBM PC XT, and the IBM PC AT. Later, Microsoft specified the design with its "platform specification" for Windows. Microsoft could do this, due to its dominance of the market for operating systems and office software.

Today, the PC design is governed by various committees and standards organizations. They specify the design for things like the BIOS (or its replacement the UEFI), the power supply, and connectors for accessories. Individual companies have sway; Intel designs processors and support circuitry used in all PCs. Together, these organizations provide a single design which allows for modest variation among manufacturers.

That uniformity is starting to fracture.

Apple's computers joined the PC design in the mid-2000s. The "white MacBook" with an Intel processor was a PC design -- so much so that Windows and Linux can run on it. Yet today, Apple is moving their Macs and MacBooks in a direction different from the mainstream market. Apple-designed chips control certain parts of their computers, and these chips are not provided to other manufacturers. (Apple's iPhones and iPads are unique designs, with no connection to the PC design.)

Google is designing its Chromebooks and slowing moving them away from the "standard" PC design.

Microsoft is building Surface tablets and laptops with its proprietary designs, close to PCs yet not quite identical.

We are approaching a time when we won't think of PCs as completely interchangeable. Instead, we will think of them in terms of manufacturers: Apple PCs, Microsoft PCs, Google PCs, etc. There will still be a mainstream design; Dell and Lenovo and HP want to sell PCs.

The "design your own PC" game is for serious players. It requires a significant investment not only in hardware design but also in software. Apple has been playing that game all along. Microsoft and Google are big enough that they can join. Other companies may get involved, using Linux (or NetBSD as Apple did) as a base for their operating systems.

The market for PCs is fragmenting. In the future, I see a modest number of designs, not the thousands that we had in 1980. The designs will be similar but not identical, and more importantly, not compatible - at least for hardware.

A future with multiple hardware platforms will be a very different place. We have enjoyed a single (evolving) platform for the past four decades. A world with multiple, incompatible platforms will be a new experience for many. It will affect not only hardware designers, but everyone involved with PCs, from programmers to network administrators to purchasing agents. Software may follow the fragmentation, and we could see applications that run on one platform and not others.

A fragmented market will hold challenges. Once committed to one platform, it is hard to move to a different platform. (Just as it is difficult today to move from one operating system to another.) Instead of just the operating system, one will have to change the hardware, operating system, and possibly applications.

It may also be a challenge for Linux and open source software. They have used the common platform as a means of expansion. Will we see specific versions of Linux for specific platforms? Will Linux avoid some platforms as "too difficult" to implement? (The Apple MacBooks, with their extra chips for security, may be a challenge for Linux.)

The fragmentation I describe is a possible future -- its not here today. I wouldn't panic, but I wouldn't ignore it, either. Keep buying PCs, but keep your eyes on them.

For compatibility, look across and not down

The PC industry has always had an obsession with compatibility. Indeed, the first question many people asked about computers was "Is it PC compatible?". A fair question at the time, as most software was written for the IBM PC and would not run on other systems.

Over time, our notion of "PC compatible" has changed. Most people today think of a Windows PC as "an IBM PC compatible PC" when in fact the hardware has changed so much that any current PC is not "PC compatible". (You cannot attach any device from an original IBM PC, including the keyboard, display, or adapter card.)

Compatibility is important -- not for everything but for the right things.

The original IBM PCs were, of course, all "PC compatible" (by definition) and the popular software packages (Lotus 1-2-3, Wordstar, WordPerfect, dBase III) were all "PC compatible" too. Yet one could not move data from one program to another. Text in Wordstar was in Wordstar format, numbers and formulas in Lotus 1-2-3 was in Lotus format, and data in dBase was in dBase format.

Application programs were compatible "downwards" but not across". That is, they were compatible with the underlying layers (DOS, BIOS, and the PC hardware) but not with each other. To move data from one program to another it was necessary to "print" to a file and read the file into the destination program. (This assumes that both programs had the ability to export and import text data.)

Windows addressed that problem, with its notion of the clipboard and the ability to copy and paste text. The clipboard was not a complete solution, and Microsoft worked on other technologies to make programs more compatible (DDE, COM, DCOM, and OLE). This was the beginning of compatibility between programs.

The networked applications and the web gave us more insight to compatibility. The first networked applications for PCs were the client/server applications such as Powerbuilder. One PC hosted the database and other PCs sent requests to store, retreive, and update data. At the time, all of the PCs were running Windows.

The web allowed for variation between client and server. With web servers and capable network software, it was no longer necessary for all computers to use the same hardware and operating systems. A Windows PC could request a web page from a server running Unix. A Macintosh PC could request a web page from a Linux server.

Web services use the same mechanisms for web pages, and allow for the same variation between client and server.

We no longer need "downwards" compatibility -- but we do need compatibility "across". A server must understand the incoming request. The client must understand the response. In today's world we ensure compatibility through the character set (UNICODE), and the data format (commonly HTML, JSON, or XML).

This means that our computing infrastructure can vary. It's no longer necessary to ensure that all of our computers are "PC compatible". I expect variation in computer hardware, as different architectures are used for different applications. Large-scale databases may use processors and memory designs that can handle the quantities of data. Small processors will be used for "internet of things" appliances. Nothing requires them to all use a single processor design.