Retro Computing Archives

Expanded vs Extended memory, or EMS vs XMS

Dave Farquhar Retro Computing August 11, 2017October 5, 2019Bill Gates, intel, memory slots, XT

DOS veterans may remember messing with expanded and extended memory to get memory above 640K. Here’s what you need to know about expanded vs extended memory, or EMS vs XMS. They are two different approaches to solving the same problem.

Dave Farquhar

David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.

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Commodore 64 Z80 cartridge

Dave Farquhar Retro Computing August 9, 2017April 3, 20231541, 1980s, 6502, apple, apple ii, commodore, commodore 64, intel, MOS, spartan

One of the most popular add-ons for an Apple II added CP/M compatibility. So I guess it should be no surprise that Commodore tried the same thing. But the Commodore 64 CP/M operating system and the associate Commodore 64 Z80 cartridge was a flop. Why?

Dave Farquhar

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Why did old PCs have a turbo button?

Dave Farquhar Retro Computing August 1, 2017March 25, 20241980s, 1990s, benchmark, compaq, IBM, XT

Old PCs, especially PCs from the 1980s to the mid 1990s, have a button with the curious label “Turbo.” On some PCs, a number on the front changes when you push it, or an LED toggles on or off. Why did old PCs have a turbo button?

Turbo buttons are a quirk of old PCs, kind of like their beige color that tends to turn yellow, but it served a functional purpose.

Dave Farquhar

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90s computer brands

Dave Farquhar Retro Computing July 27, 2017July 11, 2025

Some 90s computer brands are the same as today, but a lot more companies played in the field than now. Profit margins were higher then, so industry consolidation wasn’t the matter of survival that it is now. The most popular computer brands of today were among the most popular brands in the 90s, but some popular 1990s computers no longer exist in any form.

Here’s a look back at some of the brands of old, including some famous PC brands, some not-so-famous, and some notorious. The 1990s were certainly a make or break time for many of them, arguably just as volatile as the merciless 1980s had been.

Dave Farquhar

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Commodore 256: The 8-bit that never was

Dave Farquhar Retro Computing July 21, 2017November 15, 20241980s, amiga, CBM, commodore, commodore 64, DEC, IBM, IRA

In 1985, Commodore followed up on its best selling Commodore 64 with a model with twice as much memory. The design of the 128 offered the possibility of following up with a Commodore 256. It never happened. Instead, Commodore moved on from 8-bit machines after the 128. Here’s why.

Dave Farquhar

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Disadvantages of the 8086 microprocessor

Dave Farquhar Hardware, Retro Computing July 11, 2017August 11, 20176502, amd, apple, Apple Lisa, DEC, IBM, intel, MOS, motorola, x86

An 8086-series microprocessor, the 8088, powered the original IBM PC. Its direct descendants power PCs to this day. Not only that, they power modern Macs too. This was always controversial, especially running Mac OS on Intel chips. Why? What are the disadvantages of the 8086 microprocessor?

Dave Farquhar

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What happened to Compuserve?

Dave Farquhar Retro Computing July 6, 2017February 14, 2026

Compuserve was an online service for dialup modems from the 1970s to the 1990s. It was a way of getting online and communicating with others before the Internet was generally available to individuals. Later, it became a primary way for individuals to connect to the Internet, turning itself into an Internet Service Provider. But over time, it faded away into history. Here’s what happened to Compuserve.

Dave Farquhar

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Using compact flash as a hard drive

Dave Farquhar Retro Computing July 5, 2017August 1, 20171990s, pentium ii

Old IDE hard drives are slow and unreliable, due to their age. What if I could tell you there’s a cheap, readily available substitute that’s both solid state and faster? There is. Let’s talk about using compact flash as a hard drive.

Dave Farquhar

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Why did IBM fail at PCs?

Dave Farquhar Retro Computing July 3, 2017October 4, 20211980s, 1990s, acer, AIX, apple, compaq, datacenter, dell, hp, IBM, intel, lenovo, mainframe, Packard Bell, Personal Computer, proprietary unix, thinkpad, unix, VHS, XT

If you ask why did IBM fail, I assume you mean why did IBM ultimately fail in the personal computer market. IBM is still in business, after all. But its exit from the PC market after 24 years, including a period of dominance in the 1980s, does seem curious. And it raises another question: What does IBM do now?

I experienced IBM’s fall in this market firsthand. I sold computers at retail in 1994 and 1995. IBM’s computers at that time were no worse than anyone else’s, but I had an extremely difficult time selling them. Many consumers didn’t trust IBM and didn’t want to get somehow locked in. There was nothing wrong with those machines, but it sure was a lot easier to just sell them a Compaq.

Dave Farquhar

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What is retro gaming?

Dave Farquhar Retro Computing June 30, 2017March 26, 2024

What is retro gaming? What are retro games? The specifics depend on your age, but it generally means playing older video or computer games today, whether that means playing the games on older hardware or recent hardware. The part people argue about is what’s old enough to constitute retro.

There isn’t a lot of agreement or consensus about that, and I have some ideas why.

Dave Farquhar

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