You Can't Appreciate the Pi without Retro Computers

(1974)

This is the machine that is widely credited with launching the PC revolution. It's notable for launching Microsoft. Looking at it, having grown up in a world where personal computers were around before I was born, it doesn't look like much. The Altair 8800 system consists of a metal case, a power supply, a front panel with switches, and a passive motherboard with expansion slots. 

There's no display screen or keyboard.  Those would have cost too much back in 1974. What it did was launch the concept of the personal computer; the first microprocessors created by Intel, and inspired Bill Gates to drop out of college and start Microsoft.

While an argument can be made that the PC was inevitable, it was just a matter of who would win the gold rush, a January 1975 article in Popular Mechanics, really got the ball rolling with the cover, “Project Breakthrough! World’s First Minicomputer Kit to Rival Commercial Models… ‘ALTAIR 8800’” The headline inside read: “Exclusive! ALTAIR 8800. The most powerful minicomputer project ever presented – can be built for under $400.”

Paul Allen would said the issue “stopped me in my tracks” and brought a copy to his friend Bill Gates and the two of them decided to write a version of BASIC for the machine.  ALTAIR BASIC would be the first product they sold when they started their company Micro-soft.

Although games were not among the list of 23 potential applications the machine could be used for, games were amongst the first use for most buyers.   In the image on the right you can see an example of one such game.   Since there are no keyboards or monitors with the machines you would

At a time where Heath Kit Projects were common, this was by most accounts typically harder to put together than your standard kit. You were given just 256 bytes of memory and no peripherals. The most you could hope for is to get the lights to blink in certain patterns.

Bill Gates and Paul Allen had the vision for creating a “true” programming language by writing an interpreter for Machine Language. The stories for Microsoft and Intel are forever intertwined with the history of the ALTAIR 8800.

All of the circuitry - the CPU and memory, are on cards which plug into the expansion slots which was called Altair Bus and later renamed S-100 Bus as it became the industry standard.

CPU: Intel 8080

 

Introductory Kit Price: $439 (roughly around $1,953.92 adjusted for inflation)

 

Introductory Assembled Price: $621 (roughly around $2763.93 adjusted for inflation)

(1976)

While the Raspberry Pi is truly revolutionary, it’s hardly the first single-board computer, which have been around since near the dawn of the computer revolution. Credit for the first true single board computer goes to the “dyna-micro” which was based on the Intel C808A, and also used Intel’s first EPROM, the C1702A. Rebranded as “MM-1” (Mini-Micro Designer 1) by E&L Instruments in 1976, and made popular in the 8080 “BugBook” series of the time. Single-board computers, in fact, figured heavily in the early history of home computers, with Acorn Electron and the BBC Micro being the most prominent example.

While I was unable to see examples of these early single board computers, I was able to get an up close demonstration of another early single board computer, the KIM-1, which like the Raspberry Pi, often shipped without an enclosure. That I was in San Mateo representing the element14 community and here to answer as many question as possible about the Raspberry Pi was probably not lost on my guide.

To be honest, the full significance of what he was showing me was lost on me at the time.   It was only after going through the images I shot and researching what I was shown that I was able to fully appreciate what he was showing me.

The KIM-1, short for Keyboard Input Monitor, was a small 6502 based single-board computer developed and produced by MOS Technology, Inc. It originally used Mos Technology’s first processor, the 6501, but that had to be replaced with a 6502 when Motorola immediately sued them.  That’s because the 6501 processor allowed the boards to plug into existing boards that used the Motorola 6800, allowing engineers and hobbyists to get a development system running with existing hardware.

At the same time the 6502 was being released, MOS’s entire calculator IC market collapsed, leaving Commodore Business Machines (CBM), a company that had invested heavily in the calculator market to bail them out. With their purchase of MOS Technologies, Commodore developed their first computers. MOS was an IC producing factory and Commodore took it over to ensure a constant supply of IC.

Once the new processor was used you could no longer use the boards to get a system up and running immediately. That’s because it no longer allowed users to use an existing machine to allow users to quickly start playing with the CPU.  Under Commodore, the board became noteworthy for its low price and easy-access expandability.

You could set up a complete system that would run you $245 via a kit. You would need to add your own power supply, a used terminal and a storage medium (in this case a cassette tape drive). Books with small assembly language programs were written and once the units became popular, an easy memory expansion allowed you run a Tiny BASIC programming language. That was if you were able to survive the 15-minute, error prone ordeal of loading BASIC from cassette tape.

While originally intended for engineers, the KIM-1 found a large audience with hobbyists.

CPU: MOS 6502, 1MHz

 

Memory: 1024 bytes RAM, 2048 bytes ROM

 

Introductory Price: $245 (roughly around $1,077.49 adjusted for inflation)

(1976-1977)

About 22 miles from where we were standing the Apple 1 was conceived, in the bedroom and not the garage of Steve Wozniak’s home on 11161 Crist Drive in Los Altos. In the booth next to me, it’s probably no accident that Ben Heck brought his legendary Apple 1 replica to display. It was Ben who first called my attention to the computer booth where I eagerly took time in my morning to take in as much as I could. While the build that Ben brought had a built in LCD, and clampdown design, in his signature style, the one I looked at was about as authentic to an Apple 1 reproduction as I would ever see. There are after all only 66 known to be in existence, with a working unit sold for a cool $905,000 in 2014.

While the movie Pirates of Silicon Valley would have us believe that Woz listlessly sat down and made a halfhearted plea with an HP suit who let him get out of the clause in his contract which gave them control of anything he made, after which he celebrated his rejection with Steve Jobs, the truth is less Hollywood. Woz in fact offered the Apple -1 design to his current employer Hewlett Packard a total of five times, getting turned down each time. It’s a well known fact, that he didn’t make the Apple-1 to “make a lot of money” and that he “gave away (his) designs for free.”  It took someone with the power of persuasion of a Steve Jobs to convince him to try and sell the computer.

It was on March 5, 1975, at the first Homebrew Computer Club in Gordon French’s garage, that Steve Wozniak became inspired to begin work on what would become the Apple-1. The first prototype for the very first Apple-1 computer prototype was based on the $175 Motorola 6800 CPU. When Motorola engineers released a $25 MOS 6502 CPU, he adapted the system around the chip to make the Apple-1 more affordable.

The Apple-1 used a cassette tape interface and ran at just 1.023 MKz with 4KB or RAM that was expandable to 8KB or 48KB. The first game released for Apple-1 was a Star Trek game that sold on cassette for $5. 

The Apple-1 consisted of a single motherboard, with about 60 chips fully assembled. This was not the norm at the time as kits for building your own computer consisted of multiple circuit boards. The motherboard was the only thing that came preassembled, it was up to the owner to come up with their own custom enclosure. Another ingenious idea that Woz came up with was to come up with motherboard support for CRT TV compatibility – a novel approach for the time. Woz built 200 units of the Apple-1 by hand, all of which but 25 sold during its short time on the market. As Wozniack was the only one who could provide support for the units, when the Apple II was released in 1977, owners were encouraged to trade up their units and many Apple 1 units were destroyed.

CPU: MOS 6502, 1.0 MHz

 

Memory: 4K, 65K max RAM, 256 bytes ROM

 

Introductory Price: $666.66 (roughly around $2806 adjusted for inflation)

(1977-1993)

As with many people my age, the Oregon Trail Generation, the Apple II holds a special place in my heart.  It was the first computer I ever used and the first system I used to play video games (actually the Apple IIe).

It recalls perforated banners with crude graphics that we thought were amazing; games like Karateka and Ms. Pacman using an Apple joystick and educational games like Oregon Trail and Where in the World is Carmen Sandiego at school; floppy disks; and word processing programs to teach us to type without looking at the keyboard. It was my introduction to the world of computing and it reminds me of a simpler time without email, the Internet, social media, cassette decks, VHS, and when MTV actually played music videos

It’s the 8 bit game system my brother owned before I got my first 8 bit system, the Nintendo Entertainment System.

The Apple II, I was now looking at now was an early version of a series of computers that would continue to run for 23 years until it was finally discontinued in 1993. The Apple II was introduced by Steve Jobs and Steve Wozniack at the West Coast Computer Faire and the first consumer product ever sold by Apple Computer. It was promoted as an extraordinary computer for ordinary people with Woz once again primarily responsible for the design and Jobs overseeing development of Apple II’s foam-molded plastic case. Rod Holt developed the switch power supply.

Steve Jobs convinced Jerry Manock, formerly a designer for calculators with HP, to create the shell for the Apple II. It was inspired by kitchen appliances and used to conceal the internal mechanics. Unlike the Apple I, it had a user-friendly design and was sold as a self-contained unit.

It utilized a MOS Technology 6502 microprocessor running at 1.023 MHz and the Integer BASIC programming language was built into the ROM. While it initially shipped with cassette storage, the company introduced a floppy disk drive, the Disk II, la year later. The Disk II interface is an engineering masterpiece for its economy of electronic components. With a few small-scale logic chips and a cheap PROM (programmable read-only memory), he created a functional floppy-disk interface at a fraction of the cost of standard circuit configurations. 

The Apple II is notable for it s use of a multiplicity of idiosyncratic shortcuts to save hardware and reduce cost.

In a May 1977 issue of Byte, Steve Wozniak published details on the design in an article using the following examples:

• Taking advantage of the way that 6502 processor only accesses memory on alternate phases of the clock cycle, the video generation circuitry’s memory access on the otherwise unused phase avoids memory contention issues and interruptions of the video stream.
• This arrangement simultaneously eliminated the need for a separate refresh circuit for the DRAM chips, as the video transfer accessed each row of the dynamic memory within the timeout period.
• Rather than use a complex analog-to-digital circuit to read the ouputs of the came controller, Woz used a simple circuit whose period is proportional to the resistance of the game controller, and used a software loop to measure the timer.

  A single 7 MHz master oscillator was divided by various ratios to produce all other required frequencies, including microprocessor clock signals, the video transfer counters, and the color burst samples.

CPU: MOS 6502, 1.0 MHz

 

Memory: 4K min, 48K max RAM, 12 K RAM

 

Introductory Price: $1,298 (roughly around $5,130 adjusted for inflation)

(1977-1981)

Here’s another example to prove how influential the Altair 8800 was in shaping the computer industry. Back in 1975, Don French was a buyer for Radio Shack (the American electronics chain owned by Tandy Corporation) and purchased his Altair 8800 to use for inventory control.

He used the Altair to work on his own microcomputer kit and lobbied the Vice President of Marketing, John Roach, to try and sell it.  While the design itself did not interest Roach, the idea of selling a microcomputer did.

In mid-1976, Roach and French visited National Semiconductor, headquartered in Santa Clara, about 24 miles from San Mateo where the Maker Fair was located. National Semiconductor now operates as the “Silicon Valley” division of Texas Instruments as of September 23, 2011.

It was at National Semiconductor that the two men came across Steve Leininger, whose expertise on the SC/MP microprocessor impressed them.  Steve Leininger was a member of the Homebrew Computer Club, the same Homebrew Computer Club that inspired Steve Wozniak to build the Apple-1.

National Semiconductor was unwilling to provide Leininger’s contact info, but the two men were able to find him working part time at the Byte Shop. The Byte Shop, helped popularize computing to hobbyists, and was in fact the first retailer to sell the Apple 1 that fellow Homebrew Computer Club member Wozniack made.

Leininger and French began working together in June 1976. Here’s where things get interesting. The company had envisioned using Leininger to help them make a kit but Leininger had the foresight to know that “too many people couldn’t solder” and they should make a preassembled computer instead.

The Model I that I looked at combined the mainboard and keyboard in one unit, although it had a separate power supply unit. It used a Zilog Z80 processor clocked at 1.77 MHz. The basic model originally shipped with 4K of RAM, consisting of eight 2104 chips (4kx1) and eventually 16k of RAM consisting of eight 4116 chips (16kx1).

The OS ROMs I/O area video memory and OS work space occupy the first 16k of memory space on the Model 1 the remainder is free RAM that can be used by programs Although the Z80 CPU can use port-based I/O the Model I’s I/O is memory mapped aside from the cassette and  RS-232RS-232 ports

The memory layout rendered it incompatible with CP/M (Control Program/Monitor), although CP/M was offered it defeated the purpose of the OS which was portability.  Like the Apple II, the original model could not display lower case letters.

CPU: Zilog Z80 @ 1.774 MHz

 

Memory: 4 KB, 48 KB max

 

Introductory Price: $600 (roughly around $2400 adjusted for inflation)

(1977-1983)

The 1978 release of Space Invaders, followed by the first use of vector technology for games like Asteroid a year later, ushered in the golden age of arcade games.  It was during the late 70s running up until the mid 80s that arcade games experienced their greatest popularity and technological innovation. Prior to this time, pinball machines were more popular than video games.

Capitalizing on the popularity of coin-operated video arcades, manufacturers like Atari brought the arcade experience home with affordable consoles that plugged directly into the TV. Originally dubbed the Atari VCS, the Atari 2600, would dominate the console industry of its time.

Atari wasn't the only game around at the time. By 1979, the Atari 2600 faced increasing competition from rivals Mattel Intellivision and the Magnavox Odyssey2. By 1980, Atari was looking for a mega-hit to set it apart and remain dominant. They found one with the home release of a game from Japan called Space Invaders. This became the first videogame killer-app and led many people to purchase the Atari 2600 just to play it.

The Atari 2600 is often called the godfather of modern videogame systems and is credited with helping spawn a multi-billion dollar industry.  It would become the best-selling American made console by selling 30 million units. A record that would not be displaced until the Xbox 360 sold 84 million units.

CPU: 8-bit MOS 6507@ 1.19 MHz

 

Memory: 128 bytes RAM, 4 kB ROM

 

 

Introductory Price: $199 (roughly around $786.49 adjusted for inflation)

(1977-1982)

The first desktop computer by Commodore was the Commodore PET. PET is short for Personal Electronic Transactor. Most likely this was something that they just made up as it’s likely that word PET was used as a way to capitalize on the pet rock fad that was going on at the time.  Reminds me of how Apple came up with the name for LISA when Jobs initially insisted it wasn’t named for his daughter (or maybe that’s something I just saw in a movie that may not necessarily be true). An argument can be made that the KIM-1 was the first computer by Commodore, but others would argue that the title for first computer by Commodore goes to the PET because they inherited the KIM-1 when they acquired MOS technologies.

When Chuck Peddle, the engineer who worked on the 6502 CPU and the KIM-1 for MOS Technologies, became a full-time employee of Commodore, his first order of business was to convince his new employer that calculators were “out” and computers were “in”. Having successfully lobbied his cause he went on to design the PET as one of the first user-friendly computers.

The Commodore PET was built around the MOS Technologies 6502 CPU, as was the Apple II and other popular computers of the day. A nice touch with the PET that was both user-friendly and stylish was its distinctive built-in display.   Some PETs had a black screen-trim while others were blue.

Everything was built-in to the unit including the keyboard and cassette.  While the built-in cassette drive clearly worked with the design, the keyboard did not come off so well.  The keys were too small making it difficult to type on, and making touch-typing impossible.

The all-in-one design of the Commodore PET made it popular with schools.  The 2001 model that was on display at the Faire is the only one that had the problem with the tiny keyboard.   

CPU: MOS Technology 6502 @ 1 MHz

 

Memory: 4 K or 8 K RAM, 14 K ROM

 

Introductory Price: $795 (roughly around $3,176 adjusted for inflation)

(1977-1982)

A TI-99/4A that I remember seeing growing up was the next computer that I got a chance to see. This was an enhanced version of the TI-99 released in 1979, and the more successful of the two models.

While Texas Instruments is based in Dallas, their role in helping shape what would become Silicon Valley is indisputable.

After the first workable silicon transistor was created at Bell Labs early on January 26, 1954; Gordon Teal of TI created the first commercial silicon transistor and tested it on April 14, 1954.

In 1958, Texas Instruments, along with Industrial Development Engineering Associates (I.D.E.A.), produced the first commercially available transistor radio, Regency TR-1.  It used germanium transistors as silicon transistors were too expensive at the time. That same year, Jack Kilby, an employee at TI’s Central Research Labs, invented the integrated circuit.

  Texas Instruments also invented the handheld calculator, a prototype called “Cal Tech” in 1967 and Texas Instruments received the first patent on a single-chip microprocessor in 1973.  It’s against this backdrop of innovation that TI took its first stab at the home computer market in 1979.

It was the TI-99/4A home computer, an enhanced version of the TI-99/4 model, that proved to be the more moderately and viable which provided a lower priced and more alternative to the more expensive Apple II and TS 80.

Both TI-99 and TI-994A computers used a 16-bit processor making them the first 16-bit home computers. The CPU, motherboard, and ROM cartridge slot are built into the keyboard. A power regulator board is housed below the cartridge slot and the external power supply is a step-down transformer.

The TI-99/4A used a 16-bit TMS9900 CPU running a 3.0 MHz. The TMS9900 was based on TI’s range of TI-990 mini computers. Although the CPU is a full 16-bit processor, only the system ROMs and 256 bytes of scratchpad RAM are available on the 16-bit bus. All other memory and peripherals are connected to the CPU through a 16-8-bit multiplexer.  

CPU: TI TMS9900 @ 3 MHz

 

Memory: 256 bytes "scratchpad" RAM + 16 KB VDP (graphics RAM)

 

Introductory Price: $525 (roughly around $1,383 adjusted for inflation)

(1986-1991)

The final computer I looked at was the Tandy CoCo3. This was the last in a line of The Radio Shack TRS-80 Computers, affectionately referred to as CoCo. The CoCo3 came with 128K RAM that was upgradeable to 512K.

The Motorola 6899E microprocessor ran at 0.895 MHz in the CoCo 1 and 2, in the CoCo 3 it ran at that frequency by default but was software controllable to run at twice that rate.

As its microprocessor was still 8 bit it couldn’t access the 128K (or 512K) of RAM simultaneously and used several RAM banks which could be switched.

CPU: Motorola 6809E @ .895 MHz

 

Memory: 128 kB of RAM, upgradable to 512 kB

 

Introductory Price: $399 (roughly around $1,160 adjusted for inflation)