6502 Archives

Home » 6502

Commodore RAM expansion units

Dave Farquhar Retro Computing August 25, 2017August 24, 20241541, 1980s, 1990s, 6502, commodore, IBM, quantumlink, ram disk

The 6502-family CPUs in Commodore 8-bit computers famously used 64K of RAM at a time. But in 1985, Commodore introduced a cartridge that added up to 512K of RAM to the 128. Commodore followed up soon after with a 256K cartridge for the 64. How did Commodore RAM expansion units work?

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.

dfarq.homeip.net

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

dfarq.homeip.net

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

dfarq.homeip.net

The Atari 2600 CPU: The MOS 6507

Dave Farquhar Retro Gaming May 29, 2017January 19, 20251980s, 6502, amiga, apple, apple ii, atari, atari 2600, Chuck Peddle, commodore, commodore 64, intel, jack tramiel, macintosh, MOS, motorola, NES, nintendo, nintendo nes, radio shack

The Atari 2600 CPU was a nondescript MOS 6507 chip. Neither Intel nor Motorola had a CPU chip in the early 1970s that could meet Atari’s price point. MOS Technology didn’t have one either, but they asked Atari what they could afford. Then they made one.

The 6507 is so nondescript, some of them don’t even have the number “6507” anywhere on them.

Dave Farquhar

dfarq.homeip.net

Radio Shack computers

Dave Farquhar Retail, Retro Computing May 25, 2017February 5, 20251980s, 1990s, 6502, apple, apple ii, atari, Bill Gates, commodore, commodore 64, compaq, IBM, ibm pcjr, intel, Japan, Missouri, motorola, radio shack, Tandy, tandy 1000

Radio Shack released one of the first home computers, the TRS-80 Model I, in 1977. Between 1977 and 1979, it sold 100,000 units. Radio Shack sold them just as quickly as Tandy could make them. You can count Radio Shack and its parent company Tandy among computer companies that failed, but they enjoyed a good run. For a time, Radio Shack computers, later marketed as Tandy computers, were very popular.

Radio Shack and Tandy computers included the TRS-80 Model I from the inaugural class of 1977, the pioneering Model 100 portable, and the Tandy 1000 series, which helped bring PC clones into homes.

There were several reasons why Radio Shack computers were hard to compete with in the late 1970s and throughout the 1980s.

Dave Farquhar

dfarq.homeip.net

Commodore 64 vs Amiga

Dave Farquhar Retro Computing March 3, 2017September 6, 20181980s, 1990s, 6502, amiga, amiga os, atari, atari st, commodore, commodore 64, compaq, hp, intel, kmart, motorola, Packard Bell, Personal Computer, unix, XT

Looking at the Commodore 64 vs Amiga seems a little odd, at least to me. After all, the machines were never intended to be rivals. The Amiga was supposed to succeed the 64. Commodore bought Amiga because they couldn’t make a 64 successor on their own, so they intended for the Amiga to replace it. It didn’t fully succeed, and maybe that’s why the comparison is still interesting.

Looking back, the machines may seem similar today. But in 1985 they sure didn’t.

Dave Farquhar

dfarq.homeip.net

History of overclocking

Dave Farquhar Retro Computing January 11, 2017April 15, 20261980s, 1990s, 6502, amd, amiga, asus, Chuck Peddle, DIY, IBM, intel, motorola, overclocking, pentium ii

Overclocking didn’t start in the 90s, and it wasn’t limited to PCs either. Here’s a history of overclocking from a guy who did it some, and talked to guys who did it a lot in the 80s.

I don’t recommend overclocking, and today Microsoft can prove it’s a bad idea. But overclocking has a long and colorful history. It’s less common than it used to be, perhaps. But it’s not completely extinct.

Dave Farquhar

dfarq.homeip.net

Commodore 64 vs 128

Dave Farquhar Retro Computing May 19, 2016October 26, 20221541, 1571, 1980s, 6502, amiga, apple, apple ii, c64, commodore, commodore 128, commodore 64, tape drive

Commodore introduced the Commodore 128 in 1985 as an upgrade path from the Commodore 64, the most popular model of computer of all time. The 128 addressed the 64’s biggest shortcomings while remaining mostly compatible with its hardware and software. That makes the Commodore 64 vs 128 a natural comparison, even more natural than comparing the 64 with the VIC-20.

The Commodore 128 was an extension of the Commodore 64, with more memory, a faster disk drive, a faster CPU, and 80-column video. It also featured a very high degree of compatibility, which helped both machines sell better.

Dave Farquhar

dfarq.homeip.net

C64 vs Apple II

Dave Farquhar Retro Computing May 5, 2016September 15, 20251980s, 1990s, 6502, apple ii, commodore 64

The C64 vs Apple II was perhaps the most epic battle of the 8-bit era. Both companies sold millions of machines, yet both nearly went out of business in the process.

Comparing the two machines with the largest software libraries of the 8-bit era is a bit difficult, but that’s what makes it fun. The two machines are similar enough that some people ask if the Commodore 64 was an Apple product. The answer is no.

As a weird aside, it was possible, with a Mimic Systems Spartan, to turn a C-64 into an Apple II. Not many did, but the reason why is another story.

Dave Farquhar

dfarq.homeip.net

Commodore 64 vs VIC-20

Dave Farquhar Retro Computing December 7, 2015October 26, 20221541, 1980s, 6502, amiga, atari, atari st, commodore, commodore 64, jack tramiel, Microsoft Basic, MOS, power brick, public domain

How do you compare the Commodore 64 vs VIC-20?

The Commodore 64 and its predecessor, the VIC-20, look a lot alike, and the VIC-20’s design certainly influenced the 64. The 64 is the best selling computer model of all time, and I argue the VIC-20 was the first really successful home computer. The success of the two machines allowed Commodore to surpass Radio Shack as the sales leader in the computer industry. Yes, both Commodore and Radio Shack outsold Apple.

But even though the two machines are closely related, there are significant differences between them. It’s important to remember that in the 1980s, two years was a comparatively long time because the market was moving so fast. Plus, the VIC-20 was always supposed to be an entry-level machine. In 1982, the 64 was supposed to be fairly high-end. Let’s compare and contrast the two venerable machines.

Dave Farquhar

dfarq.homeip.net

← Previous