Creating the Commodore 64: The Engineers’ Story

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In January 1981, a handful of semiconductor engineers at MOS Know-how in West Chester, Pa., a subsidiary of Commodore Worldwide Ltd., started designing a graphics chip and a sound chip to promote to whoever needed to make “the world’s finest online game.” In January 1982, a house laptop incorporating these chips was launched on the Winter Client Electronics Present in Las Vegas, Nev. Through the use of in-house integrated-circuit-fabrication services for prototyping, the engineers had reduce the design time for every chip to lower than 9 months, and so they had designed and constructed 5 prototype computer systems for the present in lower than 5 weeks. What shocked the remainder of the home-computer business most, nonetheless, was the introductory value of the Commodore 64: $595 for a unit incorporating a keyboard, a central processor, the graphics and sound chips, and 64 kilobytes of reminiscence as a substitute of the 16 or 32 that had been then thought-about the norm.

When the chip-development undertaking began, the Commodore 64 was in no way what the designers had in thoughts. MOS Know-how was a service provider semiconductor home. Its LSI Group, headed at the moment by Albert Charpentier, had been answerable for among the chips that went into Commodore’s VIC-20 dwelling laptop, however that undertaking was already effectively into manufacturing. “We had been recent out of concepts for no matter chips the remainder of the world would possibly need us to do,” stated Charpentier, “So we determined to provide state-of-the-art video and sound chips for the world’s subsequent nice online game.”

This text was first printed as “Design case historical past: the Commodore 64.” It appeared within the March 1985 concern of IEEE Spectrum. A PDF model is out there on IEEE Xplore. The diagrams and pictures of chips, circuit boards, and screens appeared within the unique print model.

Charles Winterble, then director of worldwide engineering for Commodore, gave the go-ahead for the chip effort, and Charpentier’s group labored pretty independently till each chips had been completed in mid-November 1981.

At a gathering with Charpentier and Winterble late that month, Jack Tramiel, then president of Commodore, determined to not proceed with the online game. As an alternative, he determined, the chips would go right into a 64-kilobyte dwelling laptop to be launched on the Client Electronics Present in Las Vegas the second week of January 1982. The pc had but to be designed, however that was simply remedied.

In two days, the engineers laid out on paper the machine’s primary structure. Simply earlier than the brand new yr, they accomplished 5 working prototypes. Within the meantime, sufficient operating-system software program was copied and rewritten from the VIC-20 to provide satisfactory demonstrations of what the brand new machine may do. Following its enthusiastic reception on the Client Electronics Present, the Commodore 64 was rushed into manufacturing; quantity shipments started in August 1982 and have continued unabated.

Regardless of complaints about high quality management and the business’s slowest disk drive, the Commodore 64 has been an unparalleled success, pushing quite a lot of its rivals out of the market. A part of the explanation for its success is the worth, which retains falling—from $595 at its introduction to $149 at the moment, for which the buyer will get graphics and sound equal to or higher than that offered by machines that price 5 occasions as a lot.

Designing the subsequent nice chips

Within the late Seventies, MOS Know-how was a profitable semiconductor firm; its engineers had designed the favored 6502 microprocessor, and it manufactured a number of different solidly promoting merchandise. Commodore, a West Coast firm on the time, took over MOS in 1976—inflicting lots of the MOS engineers to stop when their inventory was purchased at 10 cents on the greenback—however MOS was allowed to function pretty autonomously.

In 1979 and 1980, recollects Charpentier, MOS Know-how developed the 6510 microprocessor—a minor revision of the 6502 with an extra input-output port, the 6526 peripheral controller, a variety of read-only reminiscence (ROM) chips, and a 4-kilobit random-access reminiscence (RAM) chip. At the moment, MOS was supplying tools to Atari Inc., Common Electrical Co., Hewlett-Packard Co., and quite a lot of different shoppers, in addition to to Commodore.

When the choice was made to design the newest in superior graphics and sound chips, step one was apparent: to seek out what the present high-quality chips may do. In assembling his design workforce, Charpentier recruited Robert Yannes, a younger engineer who had joined MOS in 1979 and had designed the VIC-20 at dwelling, from a spare prototype board. The workforce spent about two weeks researching comparable chips industrywide.

“We seemed closely into the Mattel Intellivision,” recollects Winterble. “We additionally examined the Texas Devices 99/4A and the Atari 800. We tried to get a really feel for what these corporations may do sooner or later by extrapolating from their present know-how. That made it clear what the graphics capabilities of our machine needed to be.”

The MOS designers freely borrowed concepts that they favored—sprites from the TI machine, collision-detection methods and character-mapped graphics from the Intellivision, and a bit map from their very own VIC-20. They then packed as lots of these concepts as they may right into a predefined space of silicon.

“Al [Charpentier] was given the liberty, inside a sure die measurement, to place in every part he may, working backward throughout the measurement we deliberate. When he ran out of registers he stopped,” stated Winterble. “We outlined prematurely the silicon measurement that will give a yield we had been keen to reside with; at the moment, a die measurement that was affordable in 5-micrometer know-how was lower than 200 mils. Then we prioritized the want record from what have to be in there to what ought to be in there to what we’d like to have, so the selections that had been wanted at varied factors turned pretty automated.”

9 months to first-pass silicon 

For 9 months, Charpentier labored with two draftsmen and one computer-aided-design operator on the graphics chip whereas Yannes labored with two different draftsmen and one CAD operator on the sound chip. They lacked fully the delicate design instruments of right now’s engineering workstations, however that they had one available design instrument discovered nearly nowhere else within the home-computer business: a chip-fabrication line on the premises. With this, Winterble defined, a circuit buried deep contained in the chips could possibly be lifted out and run as a check chip, permitting thorough debugging with out concern for different components of the circuitry. David A. Ziembicki, then a manufacturing engineer at Commodore, recollects that typical fabrication occasions had been a couple of weeks and that in an emergency the captive fabrication facility may flip designs round in as little as 4 days.

The price of creating the Commodore 64: Nobody is aware of.

The price of creating the Commodore 64: Nobody is aware of. “I had no formal finances accountability,” stated Winterble, “aside from Jack [Tramiel] watching me. Jack stated that budgets had been a license to steal.” As a result of MOS Know-how’s fabrication facility was not working at full capability, the tools used for C-64 check chips and a number of passes of silicon would in any other case have been idle. “We had been utilizing individuals who had been there anyway,” stated Ziembicki. “You waste a little bit little bit of silicon, however silicon’s fairly low-cost. It’s solely sand.”

Though customized chips are normally thought-about costly, the C-64 chips weren’t. Not solely had been growth prices absorbed in firm overhead, however there was no markup to pay, as there would have been inf the chips had been constructed by one other firm. And yields had been excessive as a result of the chips had been designed for a mature semiconductor-manufacturing course of.

The sound chip was designed with 7-micrometer know-how, cutting down to six in locations. (Against this, the customized chip for Atari’s Video Laptop System, fabricated 4 years earlier, was constructed with 6-micrometer know-how.) Commodore’s video chip was designed with 5-micrometer options.

As a result of design time reasonably than silicon was at a premium, the chips had been laid out merely reasonably than compactly. “We did it in a really modular style,” stated Yannes. For instance, he famous, “the usual means of constructing oscillators is to construct one after which multiplex it till you will have as many as you want. We simply constructed an oscillator module and repeated it, as a result of that was a lot sooner than understanding all of the timing for the multiplexer.”

“What was outstanding,” Winterble added, “was that 9 months later, once we got here out with the primary cross, it functioned aside from one dangerous sprite.”

In November 1981, the chips had been full. The unique intent had been a sport machine, however at this level the personal-computer market was starting to look promising. At a gathering of Charpentier, Winterble, and Tramiel, the choice was made to go for a private laptop. The subsequent option to be made, in keeping with Charpentier, was between a 16-kilobyte and a 64-kilobyte machine, because the customized chips had been designed to deal with both possibility.

“Jack [Tramiel] made the guess that by the point we had been prepared to provide a product, 64K Rams could be low-cost sufficient for us to make use of,” Charpentier stated.

When the design of the Commodore 64 started, the overriding objectives had been simplicity and low price. The preliminary manufacturing price of the Commodore 64 was focused at $130; it turned out to be $135. The pc would use the identical case because the VIC-20 and the same-sized circuit board, to hurry growth. “That wasn’t even a choice,” stated Charpentier. “It was simply frequent sense. If you happen to’ve bought a product that’s a winner, why change it?” To modify from the VIC-20 to the Commodore 64, the manufacturing group had solely to make the cartridge slot smaller, change the colour of the case, and design a brand new label.

Moreover, as a substitute of designing for efficiency first and value second, as many engineers are inclined to do, the small design workforce at Commodore had price in thoughts from the start. Yannes, for instance, had made financial system his credo when he was an impecunious high-school scholar on the lookout for components to construct a sound synthesizer. “Anytime I design one thing, I wish to use the minimal variety of elements potential. It’s a private problem. If there’s a spare [logic] gate in a gate package deal, I’ll work to do away with the complete package deal, as a result of in working with a sure variety of chips, I ought to have the ability to expend every part that’s in them. The Commodore 64 was my try to construct absolutely the minimal system that could possibly be constructed out of the video and sound chips put collectively.”

Completely satisfied New 12 months 1982!

Within the consumer-electronics business, new merchandise are historically launched to distributors, sellers, the press, and the competitors twice a yr—in the course of the first weekend in January and the primary weekend in June, on the Winter and Summer season Client Electronics Exhibits (CESs).

“Whenever you labored for Commodore,” stated Yannes, “you all the time needed to have one thing for the Winter CES.” The C-64 didn’t have a lot competitors on the winter present in 1982. Atari was nonetheless sowing its 400/800 laptop. Mattel launched the Aquarius laptop, and Spectravideo launched its laptop/sport machine, each with restricted reminiscence and capabilities.

Ziembicki recalled, “All we noticed at our sales space had been Atari individuals with their mouths dropping open, saying, ‘How will you do this for $595?’”

“We had been successful,” Winterble added.

After the present, Commodore, which had a fame for generally displaying merchandise that by no means reappeared, needed to get the 64 into manufacturing shortly. Only some design modifications had been made to prepared the machine for manufacturing. “What’s within the 64 functionally is what I needed,’ Yannes stated. “What’s within the sound chip is what I needed, and what’s within the video chip is what Al [Charpentier] needed.”

The truth is, stated Ziembicki, “after it lastly bought into manufacturing, we seemed again and requested, why did we hassle altering it after January? It wouldn’t have offered one unit much less, and we might have saved some huge cash on growth prices.”

Among the modifications had been pretty important, however they could have created as many issues as they solved. The most important enchancment was to treatment “a hiccup” within the video chip, stated Winterble.

When Charpentier first designed the video chip, he defined, his objective was optimum efficiency in each black-and-white and shade. Earlier video chips, reminiscent of these used within the Atari and the Apple, had a black-and-white frequency of seven.16 MHz—twice the tv color-clock frequency of three.58 MHz—however this might not squeeze sufficient characters on a line, and it additionally induced cross discuss between the 2 alerts, inflicting an object to shift barely to the left or proper on the display screen relying on its shade. After the January 1982 CES, when he noticed that 40 characters wouldn’t fairly match onto a TV display screen, Charpentier sped up the black-and-white clock fee and made the 2 clocks fully asynchronous. However because the shade and black-and-white units of data had been continually altering section relative to one another, “the colour transitions had been unbelievable, however there was an total swimming impact,” he recalled. The answer was to place a phase-locked loop into the system so the colour and the black-and-white data would have a relentless relationship. This, Charpentier acknowledged, was “a Band-Assist resolution.”

And that’s what it seems like, in keeping with Craig Nelson, director of product growth for Epyx Laptop Software program of Sunnyvale, Calif. “It’s a very elegant circuit,” he stated, “aside from the phase-locked loop, which is simply caught in the midst of it.” (Commodore now says it has redesigned the chip to get rid of the issue.)

On account of the “Band-Assist,” the colour data and the black-and-white data shift section by 180 levels in relation to one another on successive video fields reasonably than altering section unpredictably. This conforms extra carefully to the Nationwide Tv Techniques Committee (NTSC) normal, which requires black-and-white data to have a clock fee that’s an odd harmonic of the color-clock fee, in order that the 2 routinely reverse their relationship each different discipline—one discipline in section, the subsequent discipline out of section. (Within the NTSC normal, colours are decided by the section distinction between the colour sign and a shade reference sign transmitted firstly of every line.)

On the time the usual was developed, generally out there circuitry couldn’t fully separate the black-and-white data from the colour: modifications in shade would result in modifications in brightness and vice versa. It was to common these modifications out over time that the NTSC specified that the relative section reversal of the 2 alerts may happen on successive fields. The result’s extra pleasing shade transitions, however the section shift makes stationary figures seem to jitter. The jitter is especially apparent on skinny vertical strains, like these in alphanumeric characters. However when the Commodore 64 was conceived, it was to be primarily a sport machine, not a pc.

Operating a 5-micrometer-technology chip at an 8-MHz clock fee brought about it to dissipate an excessive amount of energy—almost 1.5 watts. Not solely did the chip run quick, however to forestall the colours from washing out, as that they had within the VIC-20, “we went to 12 volt to drive the heck out of the colour alerts,” recalled Winterble. “We knew we’d have a warmth drawback.”

At this level Winterble made one other design repair—welding a small metallic tab onto the within of the lid of the shielding enclosure across the video chip. When the pc was assembled, the tab pressed towards the highest of the chip package deal, forming a heat-conducting path and turning the shielding right into a warmth sink.

Some modifications which may have improved the machine didn’t get made within the rush to manufacturing. For instance, Yannes stated, the wires for the sound output on the printed-circuit board run alongside the wires for the video sign. Consequently, the sound output picks up an annoying 15,750 -Hz whine. Rerouting the circuit would have taken time, “and we had a board that labored,” he defined. “At that time, if you happen to had one thing that labored, you didn’t change it.” A circuit-board revision since then has rerouted these strains, Commodore stated.

However the designers did actually change some issues that labored—together with one revision that degraded the machine’s efficiency.

However the designers did actually change some issues that labored—together with one revision that degraded the machine’s efficiency. The unique design specified a high-quality radio-frequency modulator to transmit the sign to a tv set, however a less expensive modulator was substituted. “It was $6.25 to $6.50 for a very good one, and we ended up spending about $3,” Charpentier stated.

Winterble has a distinct view of the $3 modulator: “The 50-cent modulator we had been utilizing on the VIC-20 wasn’t ok,” he stated, “so we went to a costlier one.”

Digital design wasn’t the one troublesome space because the Commodore 64 went from prototype growth into manufacturing—the logistics posed a posh drawback. The C-64 was designed in Norristown, Pa., at MOS. The VIC-20 meeting line, which was to start making C-64s, was in Santa Clara, Calif. Because the C-64 went into manufacturing, Commodore was additionally opening a brand new meeting line in West Chester, Pa. There have been extra VIC-20 meeting services in Japan, the place the disk drive for the C-64 was to be manufactured. And the C-64 circuit boards had been being made in Hong Kong.

“It was a variety of enjoyable,” stated Ziembicki. “The design individuals would choose an English screw. The manufacturing finish would choose metric. However they went with what that they had. Commodore manufacturing was excellent at making issues match whether or not they had been supposed to or not. Their constitution was ‘Ship ‘em’”

“It takes a really powerful individual,” defined Charpentier, “to say ‘I’m not delivery these as a result of they’re not so good as they could possibly be’—particularly when persons are clamoring to purchase them.”

​Adjustments proceed throughout manufacturing

The beginning of manufacturing of the Commodore 64 within the spring of 1982 didn’t sign an finish to the controversy. “The hot button is to have the ability to remedy your issues when you are working,” stated Ziembicki.

One of many first battles, recalled Charpentier, was over the structure of the printed-circuit board. Commodore’s meeting plant in the USA used automated component-insertion tools, however its Japanese facility didn’t, and the 2 meeting methods required totally different element spacing. In the long run, the board for the C-64 was laid out for automated insertion, and manufacturing was moved to a brand new plant in Hong Kong that had the automated instruments.

Issues additionally plagued quite a lot of the elements—switches, for instance. “You choose a change that’s listed as a shopper change,” stated Ziembicki. “You design it in. You name the producer and get an estimate that sounds affordable. Then California [the production division] needs 50,000 every week, however the producer says, ‘We are able to’t make that. It’s a shopper change, however we’re not geared for shopper portions.’ At that time, you’re hung up.”

Since Commodore had simply moved its engineering employees from California to Pennsylvania, communication between the design engineers and the manufacturing services was not excellent, Ziembicki defined. “It bought to the purpose the place you couldn’t cease working even if you happen to didn’t get an answer—you’d simply proceed with the elements that you simply thought the manufacturing finish may get.”

And outdoors suppliers weren’t all the time dependable. “One offered an influence provide for engineering approval,” Ziembicki recalled. “It bought accepted, after which the provider modified the design and didn’t inform anyone.”

Charpentier stated that his relations with the manufacturing group had been pretty agreeable. Winterble’s dealings with them weren’t almost as cordial, however he discovered this acceptable. “I personally needed to play the heavy on a variety of stuff,” he stated. “Then Al would go in and do some good. That approach eased a variety of pressure—it was a option to get issues performed.”

Probably the most infamous drawback was “sparkle,” a defect that brought about small spots of sunshine to look on the show display screen. The issue was solved earlier than Charpentier left the corporate in September 1982, however studies of the defect continued effectively into the Christmas season, with press studies citing it for example of Commodore’s poor high quality management. Canny shoppers used it as an excuse to return completely good Commodore 64s whereas they had been beneath 90-day guarantee. Because the value of the machine had dropped $200 within the two months following its introduction, this ruse enabled house owners to acquire a refund of the acquisition value and purchase one other C-64 on the decrease determine.

Sparkle was broadly attributed to bugs within the video chip that was the guts of the system, however actually it was brought on by a ROM chip of which 3 million had been in service with no issues in different methods, together with the hit arcade online game Asteroids. Commodore engineers themselves first seemed for the issue within the video chip. It took them three weeks to identify the ROM chip because the supply of the defect, Charpentier stated. “The issue was a random occasion—it didn’t occur on a regular basis. We thought the video chip was for some cause seeing the flawed information. We didn’t even suspect it could possibly be the ROM. Lastly we put the logic analyzer on it and tracked it down.” The ROM, which Charpentier and his group had designed years earlier, had a particular pre-charging circuit to make it run sooner, however the circuit made it delicate to spurious alerts. The video circuitry and the 6510 microprocessor alternated in controlling the system bus, and when management handed type one to the opposite, voltage spikes had been generally generated.

“It simply occurred that we hit the precise timing,” Charpentier stated. “If the spike had been a couple of nanoseconds shorter or longer, it wouldn’t have been an issue. The spike was simply large sufficient that the ROM noticed it as a sound handle. It might ignore the subsequent handle request and provides the video chip flawed information.” Because the ROM contained the C-64 character set, the display screen show could be plagued by random slices of characters.

In keeping with Nelson of Epyx, “This confetti interference-looking stuff on the display screen, glowingly known as sparkle, has an especially un-nice property: it causes {hardware} collisions—the sprites imagine it actually exists.” Because the sparkle was brought on by inappropriate information fed to the video chip, it triggered the circuitry answerable for checking whether or not the movable show objects—sprites—had been overlaying background objects on the display screen. So software program that trusted collision sensing to regulate the motion of objects on the display screen would go berserk when confronted by sparkle.

The bug within the ROM was corrected, though Commodore needed to depend on exterior suppliers for some time because it ramped up its new manufacturing line. Solely the primary few hundred thousand items shipped had the defect. However, Nelson noticed, “it doesn’t matter to programmers that it was fastened. Our software program has to work in each machine on the market.” The perfect resolution for programmers, he defined, is to repeat the contents of the ROM into RAM, which is dependable. However this wastes 2 kilobytes of RAM.

​“A screw-up in my timing”

Along with the problem with the ROM, “I made a logic error,” Charpentier recalled. The error, which was corrected generally after Charpentier left Commodore, brought about the early C-64s to generate the flawed variety of clock cycles on every horizontal video line. “It was off by one,” he stated. “As an alternative of 65 clock cycles per line, I had 64.”

Consequently, the 180-degree section shift between the black-and-white and shade data, which might have eradicated color-transition issues, didn’t happen. Relying on their shade and the colour of the background, the sides of some objects on the display screen would seem barely out of line. This was corrected roughly 5 months into manufacturing.

However main edges are nonetheless an issue with the C-64. The circuitry that shows both sprite data or background data at any level on the display screen is typically gradual to reply and overlays the sprite on the background data solely after it has missed a couple of pixels.

The C-64 designers weren’t the one ones revising their machine; even some assembly-line employees bought into the act.

The C-64 designers weren’t the one ones revising their machine; even some assembly-line employees bought into the act. Since testing shade high quality routinely is just about not possible, assembly-line employees had been instructed to show a potentiometer that controls the colour and black-and-white alerts till they noticed shade. As Charpentier recalled, the employees quickly found that in the event that they turned the potentiometer so far as potential, it resulted in saturated shade—but it surely additionally worn out the black-and-white sign. A number of thousand computer systems had been shipped earlier than the assembly-line employees’ “revision” was observed; by then, some reviewers had been lambasting the C-64 for its “garish” colours.

​High quality nonetheless missing

Although these modifications have been made within the C-64 since its introductions, designers who write business software program for the machine want to see a couple of extra. One such change could be sufficient high quality management. “They don’t check,” stated Nelson of Epyx. “I’ve opened up brand-new Commodores and located traces reduce. They clearly use an influence screwdriver to assemble the C-64, generally miss the screw, and chop the traces. How, would possibly you surprise, may which have handed remaining inspection? Effectively, these traces are hooked as much as the disk-drive connectors, which they clearly don’t check.”

In hindsight, Charpentier referred to as one among Commodore’s errors “not coming a little bit nearer to high quality.”

One criticism voiced by designers of add-on {hardware} for the C-64 is that its minimalist design ends in undesirable interactions between components of the {hardware} and software program. For instance, the circuitry used to regulate the joystick and the game-paddle port is borrowed as soon as each 1/60 second to scan the keyboard for keys which have been pressed. If the joystick switches are closed, the keyboard-scanning software program will report {that a} key has been pressed. Units that connect to the joystick ports may cause unpredictable responses—an issue that will not happen if separate {hardware} had been used for the 2 capabilities.

One other flaw is the pc’s crude inside software program. The system comes up in Fundamental when it’s turned on. This can be a leftover from the times of the primary Pet laptop produced by Commodore, which had no disk-operating system, since there have been no disk drives available then. “A good disk-operating system wasn’t developed till Pet Fundamental 4.0,” Charpentier stated. The C-64 doesn’t use this superior model of Fundamental as a result of “it will have required extra ROM than we may put in.” As an alternative, the machine makes use of a much more primitive model of Fundamental, borrowed from the VIC-20.

“Software program wasn’t tangible—you couldn’t maintain it, really feel it, or contact it—so it wasn’t value spending cash for.”

Probably the most obvious omissions from the Commodore 64’s Fundamental are instructions to regulate the sound and graphics chips. “There was by no means any intention that the system would have built-in software program to regulate the graphics or the sound,” stated Yannes. “That was an apparent a part of the Commodore philosophy; you don’t waste cash on issues that make the product costlier and that almost all of patrons aren’t going to make use of.”

“Commodore has all the time paid lip service to software program,” Charpentier stated. “They do sufficient to get by after which depend on exterior sources to fill the hole. Commodore was an extension of Jack Tramiel, and to him software program wasn’t tangible—you couldn’t maintain it, really feel it, or contact it—so it wasn’t value spending cash for.”

The C-64 designers had plans of their very own for modifications which haven’t but been applied. They used the VIC-20 case to shortcut growth, however they did have a brand new case designed that they supposed to substitute in eight to 10 months. “It was thinner in entrance and had extra of a wedge form to it,” stated Charpentier. “I all the time thought the VIC-20 case seemed clunky.” A couple of new options had been additionally to be added to the machine.

The truth that these modifications haven’t been made has probably not affected the success of the C-64, asserted Brian Dougherty, president of the Berkeley Softworks of Berkeley, Calif. “This machine has the perfect graphics-display functionality of something that has but been performed for a TV display screen,” he stated. “It got here sloe to being an superior system.”

​The albatross of the C-64: its disk drive

The one main flaw of the C-64 isn’t the machine itself, however in its disk drive. With a fairly quick disk drive and an sufficient disk-operating system (DOS), the C-64 may compete within the enterprise market with the Apple and maybe with different enterprise computer systems. With the current disk drive, although, it’s hard-pressed to lose its picture as a toy.

“Enterprise-oriented software program doesn’t look pretty much as good because it ought to on the C-64,” stated Dougherty, “not as a result of the bottom system isn’t ok however as a result of the disk-drive entry is just too gradual; any enterprise software requires a variety of disk entry.” And because the DOS is so weak and lacks options reminiscent of the automated creating and sustaining of directories and retaining monitor of recordsdata, “it’s much more troublesome to develop enterprise software program” for the C-64, he added. “Someone like Lotus [Development Corp., manufacturer of a popular integrated business-software package] is dealing with much more problem than they did creating software program for the IBM PC, as a result of the PC has an operating-system construction that simply doesn’t exist for this product.

“The essential input-output system in ROM is finished pretty cleanly, in keeping with operating-system ideas. All of the routines that should be there are there, however there must also be a facility for routinely studying the primary monitor of the disk and booting a extra refined working system into reminiscence.”

The disk drive does actually have a facility for routinely studying the primary monitor of a disk, in keeping with Nelson of Epyx, however as a result of it’s not documented, it’s not broadly used.

How did the Commodore engineers botch up the disk drive?

“The disk drive? What a gory story!”

“The disk drive? What a gory story!” Charpentier stated. “That needed to do with the one advertising enter we did settle for. Advertising and marketing stated the C-64 needed to be suitable with the VIC-20.”

The disk drive on the VIC-20, Charpentier defined, was a direct descendant of the drive on the Commodore Pet laptop. “We had a parallel IEEE-488 bus for the Pet disk drive; and we used a wierd format within the early days with a view to pack information: on the outer tracks, the disk strikes sooner than on the inside tracks, so the info fee modifications with a view to pack extra information on the market. It was a pleasant thought, but it surely was clumsy, in that you simply’re incompatible with everybody else. That’s the nut this all began with.”

The VIC-20 disk drive was designed in Japan, and the bus was modified from parallel to serial to economize. The drive could be very gradual as a result of the serial-interface portion of the interface controller (the 6522) used on the VIC-20 doesn’t work. Consequently, the 6502 processor sends out one bit at a time beneath direct software program management, reasonably than sending a byte to the peripheral controller and letting it deal with clocks, information, and hand shaking.

“We fastened the serial-shift register for the 6526 [the interface controller used on the C-64 to replace the 6522] however we couldn’t use it, as a result of the disk drive needed to be suitable,” Charpentier continued. “And, as a result of the processor within the C-64is turned off for 40 microseconds each 512 microseconds, it stored lacking the interrupt alerts that management the disk interface. The answer: gradual the drive down even additional.”

Velocity was the one issue that might have been modified with out incurring the price of radical modifications within the disk drive; if the C-64 designers had been capable of forgo VIC-20 compatibility, they may have performed significantly better. And ultimately, after all, the C-64 was not suitable with the disk drive of the IC-20 anyway.

“All of it stemmed from the 6522 serial interface not working,” Charpentier concluded.

Different producers try to unravel the disk-drive drawback of the C-64. Some are promoting their very own disk drives to be used with the C-64, however they’ve discovered it troublesome to interrupt right into a market that Commodore controls. Others are promoting packages that may be loaded into RAM to hurry up disk-transfer charges, however this feature applies solely to make use of of the C-64 for programming in Fundamental; prepackaged software program loaded into the system knocks the packages out of RAM. Epyx has launched a ROM-based program to hurry disk switch fivefold. In keeping with Nelson, this system will work with any disk-based software program. “That’s potential,” stated Charpentier. “The C-64 disk drive has its personal microprocessor and reminiscence, and you may ship data to it to alter the working system and to hurry up the serial-bus protocol.”

The usual software program for the C-64 disk drive can learn a 256-byte sector each 2.5 revolutions of the disk, or 512 byes per second. Programming methods utilized by Epyx have yielded switch charges of as much as 2.5 kilobytes per second. (Amongst different gradual disk drives, Atari’s 810 transfers 1000 bytes per second, and the Apple II disk drive runs at a most of 15,000 bytes per second.)

Intelligent design shaves pennies

The Commodore workforce had labored laborious to make sure a low preliminary manufacturing price for the C-64. Vertical integration helped maintain components prices down, and Winterble vetoed concepts for added options. The designers themselves believed in counting pennies; Charpentier stated he had discovered lots” from Jack Tramiel, who was “an actual stickler for price. We agonized over each transistor.”

With a manufacturing price of $135 and a retail value of $595 at its introduction, the Commodore 64 would have a retail markup comfortably above the business normal of 1 to 3 (maybe one to 2 when volumes climb). However Commodore has continued to seek out methods to cut back each the retail value, now $149, and the manufacturing price, believed to be between $35 and $50 right now.

Commodore wouldn’t affirm this price determine. Dougherty of the Berkeley Softworks estimated the prices of C-64 components, base don his expertise at Mattel and Imagic.

  • Three ROMS at $1 every.
  • Eight dynamic Rams at $1.85 every.
  • SID (sound) chip and VIC (graphics) chip at $4 every.
  • RF modulator package deal, $3
  • 6510 microprocessor, $1 to $2
  • A handful of TTL, buffers, energy regulators, and capacitors for a complete of $5
  • Keyboard, lower than $10
  • PC board, $1 to $2
  • Plastic case, $1 to $2
  • Energy provide and miscellaneous connectors, $5 to $10
  • Packaging and guide, $1 to $2

In additional cost-cutting strikes, Commodore has changed the TTL with inexpensive customized chips and has discovered methods to extend yields on the sound and graphics chips.

Not all cost-cutting steps had been with out detrimental impact on the system. The 6567 video chip was initially packaged in ceramic, although plastic is less expensive. “We tried every kind of issues,“ Charpentier stated, “copper-lead frames, metallic inserts within the package deal, and an ungodly variety of different issues to get a plastic package deal, as a result of a ceramic package deal could be very costly. However we couldn’t discover a package deal that ran cool sufficient. Earlier than I left Commodore, I listed some concepts to cut back the ability, however half of the chip was nonetheless working at an 8-MHzclip. With no main redesign, you can not get the ability out.”

The design workforce was autonomous—they did their very own market analysis, developed their very own specs, and took their child proper up by means of manufacturing.

The chip is now encased in plastic. Commodore engineers stated that along with redesigning the chip, they’ve developed a plastic package deal that may dissipate warmth in addition to ceramic.

Because the change to plastic packaging, quite a lot of new issues with the C-64 have been reported—issues which can be machine-specific or temperature-dependent. One failing that’s broadly identified all through the software program business is an inclination for the chip to lock up when a program switches graphics modes—from displaying a bit map to displaying characters [see sidebar, “A Rich Collection of Graphics Modes”]. “A sport we had been producing began to fail on the manufacturing line,” stated Nelson of Epyx. “Then we’d check [defective disks] once more and so they’d work. It trusted which machine we put them on and what the temperature was.” Charpentier speculated that some circuit strains had been left floating within the unique design; poor processing and excessive working temperatures would stress chips to the failure level.

One other drawback that has begun to emerge in some C-64s is defective horizontal scrolling of bit-mapped screens. In a latest assessment of the Summer season Video games, an Epyx sports activities sport for the C-64, the San Jose, Calif., Mercury Information criticized the “flashbulb impact” noticeable in the course of the swimming occasion. That, in keeping with Nelson, isn’t an “impact”—the C-64 utilized by the Mercury Information reviewer merely doesn’t do horizontal scrolling correctly.

The liberty ended

Though the machine has its flaws, the designers of the Commodore 64 imagine they got here up with many important advances due to the liberty they loved in the course of the early levels of the undertaking. The design workforce was autonomous—they did their very own market analysis, developed their very own specs, and took their child proper up by means of manufacturing. However as quickly because the manufacturing bugs had been labored out and Commodore knew it had a winner, the company paperwork, which till then had been on the West Coast coping with the VIC-20 and the Pet laptop, moved in.

“At that time, many advertising teams had been coming in to ‘assist’ us,” Winterble recalled. “The subsequent product definition was going to be thought up by one group, and one other group was to be answerable for getting issues into manufacturing, and Al’s group would do R&D on chips solely.”

“If you happen to let advertising get entangled with product definition, you’ll by no means get it performed shortly,” Yannes stated. “And also you squander the flexibility to make one thing distinctive, as a result of advertising all the time needs a product suitable with one thing else.”

Charpentier summed up their frustration: “Whenever you get many individuals concerned in a undertaking, all you find yourself doing is justifying your self. I knew the Commodore 64 was technically pretty much as good and as low-cost as any product that could possibly be made on the time, however now I needed to hearken to advertising individuals saying, ‘It gained’t promote as a result of it doesn’t have this, it may’t do this.’

“The liberty that allowed us to do the C-64 undertaking will most likely by no means exist once more in that surroundings.”

​Postscript (as of March 1985)

Of the unique Commodore 64 design workforce, solely Robert Russell stays at Commodore; he’s at the moment a design supervisor. The remainder of the workforce—Albert Charpentier, Robert Yannes, and Charles Winterble, together with David Ziembicki and Bruce Crocket, who helped debug the undertaking and convey it into manufacturing—left Commodore within the spring of 1983 and shaped the corporate Peripheral Visions. Their plan was to design one other laptop. To acquire working capital, they took on a contract from Atari—to design a keyboard for the Video Laptop System, which was previewed however then, because the videogame market crashed, by no means launched. Peripheral Visions was sued by Commodore, which stated the VCS keyboard was a undertaking that belonged to Commodore. At this writing, the swimsuit had not been resolved.

Peripheral Visions has been renamed Ensoniq and can quickly launch its first product, a music synthesizer. Albert Charpentier is at the moment vp of engineering at Ensoniq, Bob Yannes is senior designer, and David Ziembicki is supervisor of manufacturing management. Charles Winterble left Peripheral Visions and is now group vp of electronics at Coleco Industries Inc. of West Hartford, Conn. And Jack Tramiel is at the moment chief govt officer of Atari Corp., the corporate that was Commodore’s chief competitor within the home-computer market earlier than shedding almost a billion {dollars} in competing towards the C-64.

To probe additional

Laptop bookstores carry a wide array of books on the C-64. Amongst these beneficial are
What’s actually contained in the Commodore 64, by Bilton Bathurst, printed by DataCap of Feneur, Belgium, and The Anatomy of the 1541 disk drive, by Lothar Englisch and Norbert Szczepanowski, printed by Abacus Software program of Grand Rapids, Mich. Laptop magazines reminiscent of Inventive Computing and Compute! assessment software program and publish packages that run on the C-64. The Commodore 64 itself could be discovered at most giant retailers.

How Programmers Exploited the C-64 {Hardware} (Slideshow)

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A Synthesizer on a Chip

“I’d labored with synthesizers, and I needed a chip that was a music synthesizer,” stated Robert Yannes, the sound-chip designer and methods architect for the Commodore 64. He started engaged on the chip within the spring of 1981, assisted by two draftsmen and one CAD operator. “No person else had a good suggestion of what we had been doing,” he stated. “Past primary analysis, which I’d been doing since highschool, the precise design took solely about 4 or 5 months.”

The main variations between his chip and the standard videogame sound chips, Yannes defined, had been its extra exact frequency management and its unbiased envelope for shaping the depth of a sound. “With many of the sound results in video games, there may be both full quantity or no quantity in any respect. That basically makes music not possible. There’s no option to simulate the sound of any instrument even vaguely with that type of envelope, besides perhaps an organ.”

Though it’s theoretically potential to make use of the amount controls on different sound chips to form the envelope of a sound, only a few programmers had ever tackled such a posh process. To make sound shaping simple, Yannes put the envelope controls in {hardware}: one register for every voice to find out how shortly a sound builds up; two to find out the extent at which the notice is sustained and how briskly it reaches that stage; and one to find out how briskly the notice dies away. “It took a very long time for individuals to know this,” he concluded.

Yannes additionally put a lookup desk within the {hardware} to transform information from musical notes to the equal frequencies, however that required extreme silicon. “I took that out,” stated Charles Winterble, who was worldwide-engineering director at Commodore in the course of the C-64 design.

The exact capabilities of the sound chip are usually not clear even right now, largely due to incorrect specs having been written when the chip was first designed. “The spec sheet bought distributed and copied and rewritten by varied individuals till it made virtually no sense anymore,” stated Yannes. An instance of the defective documentation is the declare that the chip can logically AND a number of waveforms. The chip can produce both a triangular wave, a sawtooth, or a sq. wave, relying on which bit is ready in one among its management registers. “There isn’t any interlock to make it possible for if one bit is on, the others are off,” Yannes stated. “That may have taken an excessive amount of silicon.” So if multiple waveform is elected, the interior notes of the output multiplexer are discharged, and what emerges is the minimal of amplitudes.

One other error within the spec sheet considerations the on-chip filters. “The filter was the very last thing that was labored on,” Yannes acknowledged. “I ran out of time. The pc simulation stated, ‘This won’t work very effectively’—and it didn’t.” The filter might have been mediocre, however the equations describing the way it labored had been simply plain flawed, Yannes recollects. “They didn’t cling collectively. Nobody gave me an opportunity to appropriate them.”

Confronted by these incorrect equations, most software program designers use solely the sound chip.

Among the Japanese programmers who wrote early sport software program for the C-64 took a distinct strategy, Yannes famous: “They wrote it in keeping with the spec. It didn’t matter to them whether or not one thing labored or not. Consequently, packages made sound results you couldn’t hear.”

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