Use a New IEEE Normal to Design a Safer Digital World For Children

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This text was first printed as “Design case historical past: the Commodore 64.” It appeared within the March 1985 challenge 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 have 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 a substitute, he determined, the chips would go right into a 64-kilobyte residence laptop to be launched on the Shopper 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 12 months, they accomplished 5 working prototypes. Within the meantime, sufficient operating-system software program was copied and rewritten from the VIC-20 to offer satisfactory demonstrations of what the brand new machine might do. Following its enthusiastic reception on the Shopper 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 trade’s slowest disk drive, the Commodore 64 has been an unparalleled success, pushing plenty of its opponents out of the market. A part of the explanation for its success is the value, which retains falling—from $595 at its introduction to $149 at present, for which the patron will get graphics and sound equal to or higher than that supplied by machines that value 5 instances 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 most 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, remembers Charpentier, MOS Know-how developed the 6510 microprocessor—a minor revision of the 6502 with an extra input-output port, the 6526 peripheral controller, numerous read-only reminiscence (ROM) chips, and a 4-kilobit random-access reminiscence (RAM) chip. At the moment, MOS was supplying gear to Atari Inc., Normal Electrical Co., Hewlett-Packard Co., and plenty of different purchasers, in addition to to Commodore.

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

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

The MOS designers freely borrowed concepts that they preferred—sprites from the TI machine, collision-detection strategies 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 might right into a predefined space of silicon.

“Al [Charpentier] was given the liberty, inside a sure die dimension, to place in every thing he might, working backward throughout the dimension we deliberate. When he ran out of registers he stopped,” stated Winterble. “We outlined prematurely the silicon dimension that may give a yield we have been keen to reside with; at the moment, a die dimension that was affordable in 5-micrometer expertise was lower than 200 mils. Then we prioritized the want record from what should be in there to what ought to be in there to what we’d like to have, so the selections that have been wanted at numerous factors grew to become 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 subtle design instruments of immediately’s engineering workstations, however they’d one available design device discovered nearly nowhere else within the home-computer trade: a chip-fabrication line on the premises. With this, Winterble defined, a circuit buried deep contained in the chips may very well be lifted out and run as a check chip, permitting thorough debugging with out concern for different elements of the circuitry. David A. Ziembicki, then a manufacturing engineer at Commodore, remembers that typical fabrication instances have been just a few weeks and that in an emergency the captive fabrication facility might flip designs round in as little as 4 days.

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

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

Though customized chips are normally thought of costly, the C-64 chips weren’t. Not solely have been improvement 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 have been excessive as a result of the chips have been designed for a mature semiconductor-manufacturing course of.

The sound chip was designed with 7-micrometer expertise, 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 expertise.) Commodore’s video chip was designed with 5-micrometer options.

As a result of design time moderately than silicon was at a premium, the chips have been laid out merely moderately than compactly. “We did it in a really modular vogue,” stated Yannes. For instance, he famous, “the usual manner of constructing oscillators is to construct one after which multiplex it till you could 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 exceptional,” Winterble added, “was that 9 months later, once we got here out with the primary cross, it functioned apart from one unhealthy sprite.”

In November 1981, the chips have 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 have been designed to deal with both possibility.

“Jack [Tramiel] made the guess that by the point we have 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 have been simplicity and low value. The preliminary manufacturing value 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 improvement. “That wasn’t even a call,” stated Charpentier. “It was simply widespread sense. Should you’ve acquired 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 worth second, as many engineers are inclined to do, the small design crew at Commodore had value in thoughts from the start. Yannes, for instance, had made financial system his credo when he was an impecunious high-school scholar in search of elements to construct a sound synthesizer. “Anytime I design one thing, I need to use the minimal variety of elements potential. It’s a private problem. If there’s a spare [logic] gate in a gate bundle, I’ll work to eliminate all the bundle, as a result of in working with a sure variety of chips, I ought to have the ability to expend every thing that’s in them. The Commodore 64 was my try and construct absolutely the minimal system that may very well be constructed out of the video and sound chips put collectively.”

Comfortable New Yr 1982!

Within the consumer-electronics trade, new merchandise are historically launched to distributors, sellers, the press, and the competitors twice a 12 months—through the first weekend in January and the primary weekend in June, on the Winter and Summer season Shopper Electronics Exhibits (CESs).

“If you labored for Commodore,” stated Yannes, “you at all times 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 have been Atari individuals with their mouths dropping open, saying, ‘How will you do this for $595?’”

“We have 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 have 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 acquired into manufacturing, we regarded again and requested, why did we hassle altering it after January? It wouldn’t have offered one unit much less, and we’d have saved some huge cash on improvement prices.”

A number of the modifications have been pretty vital, however they could have created as many issues as they solved. The largest enchancment was to treatment “a hiccup” within the video chip, stated Winterble.

When Charpentier first designed the video chip, he defined, his purpose was optimum efficiency in each black-and-white and colour. Earlier video chips, equivalent to 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 indicators, inflicting an object to shift barely to the left or proper on the display screen relying on its colour. 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 price and made the 2 clocks fully asynchronous. However because the colour and black-and-white units of data have been consistently altering part relative to one another, “the colour transitions have been incredible, however there was an general swimming impact,” he recalled. The answer was to place a phase-locked loop into the system so the colour and the black-and-white info would have a relentless relationship. This, Charpentier acknowledged, was “a Band-Assist answer.”

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

Because of the “Band-Assist,” the colour info and the black-and-white info shift part by 180 levels in relation to one another on successive video fields moderately than altering part unpredictably. This conforms extra intently to the Nationwide Tv Programs Committee (NTSC) commonplace, which requires black-and-white info to have a clock price that’s an odd harmonic of the color-clock price, in order that the 2 mechanically reverse their relationship each different discipline—one discipline in part, the subsequent discipline out of part. (Within the NTSC commonplace, colours are decided by the part distinction between the colour sign and a colour reference sign transmitted at the start of every line.)

On the time the usual was developed, generally obtainable circuitry couldn’t fully separate the black-and-white info from the colour: modifications in colour 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 part reversal of the 2 indicators might happen on successive fields. The result’s extra pleasing colour transitions, however the part 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 price induced 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 they’d within the VIC-20, “we went to 12 volt to drive the heck out of the colour indicators,” recalled Winterble. “We knew we might have a warmth downside.”

At this level Winterble made one other design repair—welding a small steel tab onto the within of the lid of the shielding enclosure across the video chip. When the pc was assembled, the tab pressed in opposition to the highest of the chip bundle, 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, when you 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 in reality change some issues that labored—together with one revision that degraded the machine’s efficiency.

However the designers did in reality 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 great one, and we ended up spending about $3,” Charpentier stated.

Winterble has a special view of the $3 modulator: “The 50-cent modulator we have 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 improvement into manufacturing—the logistics posed a fancy downside. 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 further VIC-20 meeting amenities in Japan, the place the disk drive for the C-64 was to be manufactured. And the C-64 circuit boards have been being made in Hong Kong.

“It was numerous enjoyable,” stated Ziembicki. “The design individuals would decide an English screw. The manufacturing finish would decide metric. However they went with what they’d. Commodore manufacturing was superb at making issues match whether or not they have been supposed to or not. Their constitution was ‘Ship ‘em’”

“It takes a really robust individual,” defined Charpentier, “to say ‘I’m not delivery these as a result of they’re inferior to they may very well 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 secret is to have the ability to resolve your issues while you’re working,” stated Ziembicki.

One of many first battles, recalled Charpentier, was over the structure of the printed-circuit board. Commodore’s meeting plant in america used automated component-insertion gear, however its Japanese facility didn’t, and the 2 meeting strategies required completely different part 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 plenty of the elements—switches, for instance. “You decide a swap that’s listed as a client swap,” 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 client swap, however we’re not geared for client 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 amenities was not superb, Ziembicki defined. “It acquired to the purpose the place you couldn’t cease working even when you didn’t get an answer—you’d simply proceed with the elements that you just thought the manufacturing finish might get.”

And outdoors suppliers weren’t at all times dependable. “One supplied an influence provide for engineering approval,” Ziembicki recalled. “It acquired authorised, after which the provider modified the design and didn’t inform anyone.”

Charpentier stated that his relations with the manufacturing group have 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 numerous stuff,” he stated. “Then Al would go in and do some good. That method eased numerous rigidity—it was a approach to get issues completed.”

Essentially the most infamous downside was “sparkle,” a defect that induced 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 reviews of the defect continued properly into the Christmas season, with press reviews citing it for instance of Commodore’s poor high quality management. Canny shoppers used it as an excuse to return completely good Commodore 64s whereas they have been below 90-day guarantee. Because the worth 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 worth and purchase one other C-64 on the decrease determine.

Sparkle was broadly attributed to bugs within the video chip that was the center of the system, however in reality it was brought on by a ROM chip of which 3 million have been in service with no issues in different techniques, together with the hit arcade online game Asteroids. Commodore engineers themselves first regarded 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 mistaken information. We didn’t even suspect it may very well 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 indicators. The video circuitry and the 6510 microprocessor alternated in controlling the system bus, and when management handed type one to the opposite, voltage spikes have been generally generated.

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

Based on 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 liable for checking whether or not the movable show objects—sprites—have been overlaying background objects on the display screen. So software program that relied on 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 outdoors 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 answer 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 issue with the ROM, “I made a logic error,” Charpentier recalled. The error, which was corrected generally after Charpentier left Commodore, induced the early C-64s to generate the mistaken variety of clock cycles on every horizontal video line. “It was off by one,” he stated. “As a substitute of 65 clock cycles per line, I had 64.”

Consequently, the 180-degree part shift between the black-and-white and colour info, which might have eradicated color-transition issues, didn’t happen. Relying on their colour 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 info or background info at any level on the display screen is usually gradual to reply and overlays the sprite on the background info solely after it has missed just a few pixels.

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

The C-64 designers weren’t the one ones revising their machine; even some assembly-line staff acquired into the act. Since testing colour high quality mechanically is nearly unimaginable, assembly-line staff have been instructed to show a potentiometer that controls the colour and black-and-white indicators till they noticed colour. As Charpentier recalled, the employees quickly found that in the event that they turned the potentiometer so far as potential, it resulted in saturated colour—nevertheless it additionally worn out the black-and-white sign. A number of thousand computer systems had been shipped earlier than the assembly-line staff’ “revision” was seen; by then, some reviewers have 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 industrial software program for the machine want to see just a few extra. One such change could be enough high quality management. “They don’t check,” stated Nelson of Epyx. “I’ve opened up brand-new Commodores and located traces minimize. They clearly use an influence screwdriver to assemble the C-64, generally miss the screw, and chop the traces. How, would possibly you marvel, might which have handed remaining inspection? Nicely, 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 somewhat 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 elements 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. Gadgets that connect to the joystick ports could cause unpredictable responses—an issue that may not happen if separate {hardware} had been used for the 2 capabilities.

One other flaw is the pc’s crude inner 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. “An honest 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 could have required extra ROM than we might put in.” As a substitute, 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.”

Essentially the most obtrusive 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 consumers aren’t going to make use of.”

“Commodore has at all times paid lip service to software program,” Charpentier stated. “They do sufficient to get by after which depend on outdoors 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 improvement, 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 at all times thought the VIC-20 case regarded clunky.” A couple of new options have 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 very best graphics-display functionality of something that has but been completed 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 is just not the machine itself, however in its disk drive. With a fairly quick disk drive and an enough disk-operating system (DOS), the C-64 might 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 nearly 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 numerous disk entry.” And because the DOS is so weak and lacks options equivalent to the automated creating and sustaining of directories and maintaining monitor of recordsdata, “it’s much more troublesome to develop enterprise software program” for the C-64, he added. “Anyone like Lotus [Development Corp., manufacturer of a popular integrated business-software package] is going through much more issue than they did growing 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 fundamental input-output system in ROM is finished pretty cleanly, in keeping with operating-system ideas. All of the routines that have to be there are there, however there must also be a facility for mechanically studying the primary monitor of the disk and booting a extra subtle working system into reminiscence.”

The disk drive does in reality have a facility for mechanically 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 and marketing enter we did settle for. Advertising and marketing stated the C-64 needed to be appropriate 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 an odd format within the early days as a way to pack information: on the outer tracks, the disk strikes sooner than on the interior tracks, so the info price modifications as a way to pack extra information on the market. It was a pleasant thought, nevertheless it was clumsy, in that you just’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 below direct software program management, moderately 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 appropriate,” Charpentier continued. “And, as a result of the processor within the C-64is turned off for 40 microseconds each 512 microseconds, it saved lacking the interrupt indicators 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 in a position to forgo VIC-20 compatibility, they might have completed a lot better. And in the long run, in fact, the C-64 was not appropriate with the disk drive of the IC-20 anyway.

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

Different producers are attempting to unravel the disk-drive downside 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 applications that may be loaded into RAM to hurry up disk-transfer charges, however this selection applies solely to make use of of the C-64 for programming in Fundamental; prepackaged software program loaded into the system knocks the applications out of RAM. Epyx has launched a ROM-based program to hurry disk switch fivefold. Based on 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’ll ship info to it to vary 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 crew had labored arduous to make sure a low preliminary manufacturing value for the C-64. Vertical integration helped hold elements prices down, and Winterble vetoed concepts for added options. The designers themselves believed in counting pennies; Charpentier stated he had discovered rather a lot” from Jack Tramiel, who was “an actual stickler for value. We agonized over each transistor.”

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

Commodore wouldn’t affirm this value determine. Dougherty of the Berkeley Softworks estimated the prices of C-64 elements, 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 bundle, $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 cheaper customized chips and has discovered methods to extend yields on the sound and graphics chips.

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

The design crew was autonomous—they did their very own market analysis, developed their very own specs, and took their child proper up via manufacturing.

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

Because the change to plastic packaging, plenty of new issues with the C-64 have been reported—issues which are machine-specific or temperature-dependent. One failing that’s broadly identified all through the software program trade is a bent 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 have been producing began to fail on the manufacturing line,” stated Nelson of Epyx. “Then we’d check [defective disks] once more they usually’d work. It relied on 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 downside that has begun to emerge in some C-64s is defective horizontal scrolling of bit-mapped screens. In a latest overview 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 through the swimming occasion. That, in keeping with Nelson, is just not 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 vital advances due to the liberty they loved through the early levels of the venture. The design crew was autonomous—they did their very own market analysis, developed their very own specs, and took their child proper up via manufacturing. However as quickly because the manufacturing bugs have been labored out and Commodore knew it had a winner, the company forms, 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 and marketing teams have 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 liable for getting issues into manufacturing, and Al’s group would do R&D on chips solely.”

“Should you let advertising and marketing become involved with product definition, you’ll by no means get it completed shortly,” Yannes stated. “And also you squander the flexibility to make one thing distinctive, as a result of advertising and marketing at all times needs a product appropriate with one thing else.”

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

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

​Postscript (as of March 1985)

Of the unique Commodore 64 design crew, solely Robert Russell stays at Commodore; he’s at present a design supervisor. The remainder of the crew—Albert Charpentier, Robert Yannes, and Charles Winterble, together with David Ziembicki and Bruce Crocket, who helped debug the venture and produce it into manufacturing—left Commodore within the spring of 1983 and fashioned 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 venture 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 present vice chairman 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 vice chairman of electronics at Coleco Industries Inc. of West Hartford, Conn. And Jack Tramiel is at present chief govt officer of Atari Corp., the corporate that was Commodore’s chief competitor within the home-computer market earlier than dropping almost a billion {dollars} in competing in opposition to the C-64.

To probe additional

Laptop bookstores carry a wide array of books on the C-64. Amongst these really useful 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 equivalent to Inventive Computing and Compute! overview software program and publish applications that run on the C-64. The Commodore 64 itself might be discovered at most giant retailers.

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


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 techniques 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 have 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 foremost variations between his chip and the standard videogame sound chips, Yannes defined, have been its extra exact frequency management and its impartial 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 unimaginable. There’s no approach to simulate the sound of any instrument even vaguely with that form 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 fancy job. 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 word is sustained and how briskly it reaches that degree; and one to find out how briskly the word dies away. “It took a very long time for individuals to grasp 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 through the C-64 design.

The exact capabilities of the sound chip will not be clear even immediately, largely due to incorrect specs having been written when the chip was first designed. “The spec sheet acquired distributed and copied and rewritten by numerous 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 a interlock to be sure that 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 issues 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 properly’—and it didn’t.” The filter might have been mediocre, however the equations describing the way it labored have been simply plain mistaken, Yannes remembers. “They didn’t hold collectively. Nobody gave me an opportunity to appropriate them.”

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

A number of the Japanese programmers who wrote early sport software program for the C-64 took a special method, 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, applications made sound results you couldn’t hear.”

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