Friday, January 18, 2013

The 6560 odyssey...

The Video Interface Chip specifically known as the MOS Technology 6560 (datasheet) is the integrated circuit responsible for generating graphics and sound on the Commodore VIC-20 home computer. To tell the story of this Integrated Circuit is to tell the story of Al Charpentier and MOS Technology; and to do that we have go all the way back to the very beginning of the 20th Century...

The Allen-Bradley company was initially founded in 1903 as the Compression Rheostat Company by Dr. Stanton Allen and Lynde Bradley. They commercially manufactured crane controllers, and later developed rheostats (resistors used in applications that require current adjustment - or the varying of resistance - in an electric circuit) for use in automobile dashboards and radios. By 1970 they had grown into a supplier of various electronic components and industrial controls, and that is when they acquired a large interest in MOS Technology.

MOS Technology was just formed one year earlier in 1969 by three executives from General Instrument: Mort Jaffe, Don McLaughlin, and John Pavinen. The company designed and fabricated custom metal-oxide semiconductor integrated circuits, and had also developed a line of calculator chips as a "second source" to Texas Instruments' products. MOS Technology's biggest customer at that time was Commodore Business Machines.

However, by the mid-1970s MOS was dying. Calculator margins were shrinking dramatically. MOS really needed to win a new market. The microprocessor industry was also having problems establishing itself. Component costs were still too expensive. For MOS to drive up interest levels in new integrated circuits, they had to drive down the cost of entry. Chuck Peddle would be the visionary to make that happen. John attracted Chuck and a bunch of his close colleagues to MOS from Motorola, where they had worked on the 6800 product line.

The team's goal at MOS was to design and produce a new line of low cost integrated circuits for embedded applications, and attract a large number of customers for MOS.  Chuck has often said that they did not specifically design the 6500 product line for computer use. The 6500 line was intended to meet the demands of a wide variety of industrial and consumer products.

In June of 1975, soon after the 6502 Microprocessor's WestCon unveiling, Motorola realized they had turned their old engineers into their new competitors. Motorola immediately sued MOS for 6800 patent infringement. That frightened Allen-Bradley. As soon as lawyers got involved, Allen-Bradley walked away and gave their interest in MOS to its management team at the time.

Commodore immediately stopped paying their bills to starve MOS for cash. They then swooped in to purchased the cash-strapped company outright in 1976 – on the condition that Chuck would join Commodore as Chief Engineer. The deal went through. While MOS basically became Commodore's production arm, they continued using the MOS name for some time.

The 6502 & 6560 both run full speed!
That very same year, Al Charpentier started his career at MOS after graduating from the University of Pennsylvania in 1975, where he earned a Bachelor of Science in Electrical Engineering. In addition to working on various calculators, ROMs, DRAMs and SRAMs, he designed the 6560 Video Interface Chip ("VIC”) in 1977.

Consistent with the original design objectives for the 6500 product line, the 6560 was intended for a broad range of applications such as low cost CRT terminals, biomedical monitors, control system displays, games, etc.

[Two years pass...]

By 1979, Bill Seiler was working on the TOI project with Chuck at the Moorepark Advanced R&D Facility in San Jose, California. TOI was to be the Apple II killer. Al was helping on a new video chip for the TOI design, the 6564. Some work had also been started on a third video chip, the 6562, intended for a color version of the then successful Commodore PET.

In the meantime, freshman MOS engineer Bob Yannes, who graduated from Villanova University 1978, and was recruited to MOS by Al, partly for his music synthesis knowledge, had designed a game machine around the 6560 at home, dubbed the MicroPET. It had had no operating system or BASIC. The MicroPET became the unintended prototype of a 6560-based Commodore product.

Bill along with John Feagans, put together a 6560-based computer after some preliminary discussions with Bob, just for fun.  Bill pulled one of Commodores old printing calculators from the trash. He removed the calculator guts and modified the case to take the original small PET keyboard and then modified a PET mother board to fit inside. He sawed the PET mother board in half, removing the video section. He replaced the video section with the 6560 graphics chip. With the help of John they patched the system ROMs from the PET to use the 6560 for video display.  John said, "I made the ROM software modular in anticipation of the hardware."

6560 output adjustments
The first real problem was how to do color. The PET already had a simple way to do character graphics, so they just extended the idea to add color characters to it.  Chuck modified his cassette tape read/write routines to operate at the new clock speed for the hybrid computer. They cleaned up the calculator case and added an external PET cassette drive. Lenard Tramiel and Bill modified some PET games to have color, and use the 6560's smaller screen size. They had a rough prototype at this time which was a close resemblance to an actual computer. They shipped the prototype off to CES and it came back a big hit.

After CES, the VIC-20 was suddenly a huge project at Commodore. The design for the VIC-20 was completed in about one month. They adapted the PET's IEEE-488 parallel bus to the serial bus used for production.  Bob fed features from the ill-fated 6562 (which reportedly had a better sound generator) and the 6564 (which reportedly had more colors) back to the original 6560 chip design. The production VIC-20s would contain this thoroughly revised and improved 6560. Everything was shipped off to Japan where it was packaged with the larger PET keyboard. It was released there first, as the VIC-1001 -- a passing reference to its bigger brother, the PET 2001John's wife translated the user manual from Japanese to English in preparation for the computer's USA release.

Visiting The VIC-20 Video
by Jim Butterfield, Associate Editor, COMPUTE! ISSUES #36, #37, #38 and #39
...In which the traveler discovers a new way of viewing the computer's memory: through a video chip. This is a four-part series about the structure and uses of the VIC's video chip.  If we want to put the VIC-20 video chip to work, we must learn to see things from its standpoint. It sees the computer memory in a way that differs significantly from the way the processor chip sees it...
The 6561 die shot below is stitched from many separate microscope shots by Greg James using a Nikon LV150 with an LU Plan Fluor 20x objective. The images were corrected and stitched automatically by Christian Sattler in the UK, using Autopano-sift-C and custom code.

1600 x 1622 PNG 5.7 mb
6500 x 6588 PNG 77.7 mb

By 1982, Al would be Vice President of Engineering at Commodore, where he led the development team responsible for the Commodore 64, including the VIC-II (video) and SID (sound) integrated circuits. The C64 had barely made it out the door in 1983 when five of its six principal engineers: Al Charpentier, designer of the VIC and VIC-II video interface chips; Bob Yannes, designer of the MicroPET and SID sound interface device; Charles Winterable; David Ziembeicki and Bruce Crockette, all left Commodore and started Peripheral Visions -- which was quickly renamed Ensoniq. Their first product was a software drum machine that ran on home computers manufactured by Commodore competitor, Atari.
Al Charpentier

Today, Mr. Charpentier has over thirty years of management experience in consumer electronics technology, with expertise in the semiconductor, electronics and computer related industries. Significant innovations in his field include the design of chips (silicon), hardware and software (systems) in the following areas: calculators, microprocessors, ROM, DRAM, SRAM, video chips, audio chips, hearing aids and radar systems. He holds ten patents in the fields of semiconductor processing, chip design, hearing aids, and near field radar.

After Commodore's bankruptcy in 1994, Commodore Semiconductor Group (MOS) was bought by its former management team for $4.3 million plus expenses. In 1995, the company, operating under the name Great Mixed-signal Technologies, reopened the old plant in Norristown, Montgomery County, Pennsylvania that Commodore had closed in 1992.  However, in 2001 the EPA shut the plant down due to leaking underground hazardous waste storage tanks. The leaks from these tanks caused the local groundwater to become contaminated with trichloroethylene and other volatile organic compounds.  

Ironically, the year the EPA shut them down matches the model number of Commodore's first computer developed at MOS, the PET 2001 (which itself was a reference to a movie of the same name).  Great Mixed-signal Technologies was forced to cease operations and then liquidated.  That's quite an odyssey!

I have an additional VIC-20 blog entry: Wednesday, January 2, 2013 - Turning Japanese...

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