IBM PC History Quick Overview


My IBM PC 5150 is a “late model” from 1984, which includes CGA, 256KB RAM onboard, newer 1982 BIOS, and dual 360KB double density 5.25″ disk drives. But the 4.77 MHz 8088 processor, 5-slot ISA bus expansion, 63W power supply remains identical to the original IBM PC equipment released in 1981. The entire 5150 (along with 5160 and 5170) models continued until April 1987.

After the IBM PC launch in August 12th, 1981, then 1988 was the next “pivotal year” as IBM literally pivoted from the IBM PC over to the IBM PS/2 model (IBM was also investing in OS/2, which was actually a fine operating system, but was effectively outmaneuvered by Microsoft). This also was about the time of Adlib and Super VGA becoming more commonly available. The irony here is that multi-voice audio and “near” 1024×1024 video quality was something the PDP-1 was able to do around 1962 (see a demonstration). Although to be fair, the PDP-1 could not do both of these capabilities at the same time. Still, it took nearly 30 years for the capability to become affordable to average household users.

My IBM PC 5150 (described here) represents mainstream hardware available since 1981. These had now-long-obsolete types of connectors (serial, 8-bit ISA, Molex connectors, ribbon cables), non-standard mouse connectors, no advanced audio, and overall were painfully slow and limited. But before going more into this, I’d like to describe the more modern systems (to help orient on what these 1980 systems are NOT).

Systems after 1991 will tend to be more capable 386/486/Pentium machines (such as having CD-ROM support, use newer expansion bus standards, have standard VGA, and a more sophisticated BIOS that meant no more dip switches). These systems will probably be running Windows and could multi-task. Between 1991 and 2001 was a bit of an awkward DOS/Windows transition set of years, up until Windows XP. Note that these systems started to require heatsinks and additional cooling fans, as the processors used more power and ran hotter than the prior generation of 8-bit systems.

Essentially, this was like adding a radiator to the automobile engine, to allow the performance of the machine to operate in standard environments (and not just the ice caps). The concept of a “personal computer” had been well established (the “0 to 1” innovation), now it was a matter of making them faster and more capable.

After 2001, advanced video cards and multi-core processors started becoming more mainstream. PC users could run multiple programs as the available operating systems matured. This is ironic since even systems of the 1960s supported remote time sharing access. But to keep cost low throughout the 1980s, the IBM PC had to build up to supporting this type of capability (of multiple concurrent programs running at the same time). Again, to be fair, “time sharing” is not necessarily as glorious as multi-core parallel processing.

By the mid 2000’s, 64-bit processing was becoming standard (32-bit systems were limited to 4GB of RAM, which seemed “massive” in the late 1980s, but fairly quickly boxed in how much they could expand by the late 1990s). Another significant event was in 2005, when Apple transitioned to the “x86” Intel architecture (due to high cost of licensing PowerPC). This single step helped greatly unify the industry, as data and code could be more easily shared by having the same architecture and “endianness.”

There was a significant financial crash that began in 2008 (which was then mostly recovered by 2011). This crash was more related to real-estate and excessive loans, not related to the PC industry itself. But this crash did take focus away from certain technical development, and also motivated the introduction of Bitcoin in 2009 (which then subsequently motivated major development in GPUs, which were also in demand for use in real-time visual processing such as in self-driving cars).

The iPAD was introduced in 2012, being essentially a larger version of the 2007 iPhone. While not directly IBM PC related, these tablet devices demonstrated the benefits of “low power” and “instant on” devices. The overall market for desktop PCs had begun a decline, as the appeal to portable tablet type devices increased (thin, long battery life — in the order of 10 hours instead of 2-4 for a typical laptop computer). In fact, IBM had already sold it’s PC division in 2005 (which became Lenova).

The next real “change” wasn’t until 2015: solid state drives had become far more reliable, along with much faster system bus (PCIe 4.0) and RAM speeds (DDR4), larger onboard caches, more CPU cores, and the introduction of Windows 10. Advanced video cards became more affordable and “virtualization” was much more widely used, in addition very expensive “accelerator” cards also became available to help vastly parallelize certain types of processing. Home PCs were still popular, but also starting to return to being more like “dumb terminals” compared to the massive data centers being built.

BIOS: Basic Input/Output System was concept since the origin of the personal computer starting with the Commodore PET in 1977. A ROM would contain various “system calls” to provide various utilities to end-user applications (such as clearing the screen or placing a character on the screen). The BIOS would also coordinated the overall startup of the system. But in 2007, initiatives were underway to replace the BIOS with a new standard called UEFI. This was not an overnight transition, but ended up being a very gradual change, becoming more official in by 2020 (at least per Intel). Essentially this meant the idea of having floppy disks, installing MS-DOS, and running Doom (or any “legacy software” or pre-64bit) was becoming a thing of the past. This helped facilitate virtualization, which more smoothly allowed things like installing an operating system across a network, or installing multiple operating system (as UEFI made it easier to have provisions for loading device drivers, more easily than traditional BIOS, as well as facilitated faster boot up times by not including BIOS ROM code that performed various long-obsolete boot up checks).

Two major events after 2017: AMD introduction of the “Threadripper” and (in 2020) Apple announcing a departure from using Intel processors and manufacturing their own. Tentatively, this means for the first time since IBM/Intel introduced the IBM PC back on 1981, the prestige of Intel was beginning to crack and decline. There is growing competition in nanometer transistors, which facilitate affordable 64 or even 128 core general processors. At the same time, GPUs and accelerators are becoming more utilized in data analytics, AI, image processing, simulation, and other such advanced applications. However, the COVID epidemic of 2020 has slowed down production, impacting the overall availability of microprocessors (combined also with more processing being directed towards cryptocurrency mining).

The IBM PC has “reinvented itself” several times since its introduction in 1981, through bus interface changes, memory module evolutions, and continuously expanding processing capabilities. But the PC has maintained its overall partnership with Intel and Microsoft. There are alternatives: AMD does continue to make “x86” (or “x64”) compatible processors (as well as outstanding GPUs), and IBM purchased Red Hat Linux in 2018 (where Linux has been a viable alternative operating system for the IBM PC since the early 1990s). Aside from the idea of socketed CPU and expansion cards, modern PCs do have one essential common trait with the IBM PC 5150 ancestor: the use of CTRL-ALT-DELETE (the famous “three-finger-salute” to reset the system).

There are still many useful x86 and x64 software applications being developed and maintained (PixInsight is one of my main image processing tools for astrophotography). But there is also a whole online/cloud ecosystem of services, where this cloud itself is becoming a kind of operating system that hosts “online applications.” Google Earth and Tinkercad are two prime examples of these online applications, that provide an extensive user interface and utility, yet run exclusively within a web browser.

There is still no clear indication of the “end of the PC” era. Systems still consists of processors, RAM, and a bus to support external peripherals. Software techniques are finally catching up to take advantage of multi-core processing, leading to incredible new capabilities like blockchain, high resolution video streaming, VR, AR, AI. The Information Age will continue to bring forth amazing insights and capabilities, all spawned from the humble beginnings of 4-bit, 8-bit, 16-bit processors in the hands of very clever innovators.

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