Timeline Analog 2. John Buck
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Название: Timeline Analog 2
Автор: John Buck
Издательство: Ingram
Жанр: Изобразительное искусство, фотография
Серия: Timeline Analog
isbn: 9781925108583
isbn:
To his credit, he asked me to describe my problem. I told him that I was using many fast interrupts to drive my software, and if I received an interrupt during the execution of a 4 byte instruction the PDP-11 would trap to a fault error. He thanked me, we hung up and I turned out the lights, locked the doors and went home.
When Adams arrived at work the next day, he was directed to Butler’s office. He walked in to see CMX management plus the regional manager and local sales and maintenance staff from DEC.
He was asked why he had "broken with reporting protocols" the previous evening.
I told them I had tried that twice and was told it was my problem and I should fix it. I never spoke to the DEC people again. I found out later that the Massachusetts engineers knew they had a problem, but I don't know if they knew the exact cause. Perhaps I helped them out with my phone call.
Adams spent the next two days removing all 4 byte commands from his program code and had no further hardware traps.
I did, however, still have bad insert edits and missing switcher commands. The insert edits were occasionally a frame late, and I attributed this to a mismatch between the frame counting of the PDP-11 and the record VTR. As I indicated earlier, the frame count scheme was not 30 fps but was slightly less. I had a frame counting routine in my software, so began to focus on that.
No matter how well I tracked my counter, I could not resolve this issue. After much time observing the video signals and my commands from the processor to the VTR and sleeping on this for many fitful nights, I had an 'A-HA' moment and deduced that the computer RTC had to be tied to the 59.94 Hz video synch and not to the 60 Hz power line.
I kludged (today called 'hacked') together a circuit to make the video synch pulse look enough like the 60 Hz signal that the RTC board in the PDP-11 would react to it. Voilà, all my timing problems were solved. It turned out that if the edit commands to the VTR were late in the frame, the VTR would delay the edit until the beginning of the next frame.
Also the switcher processor was performing internal tasks during the first five or so lines of the frame and would ignore any commands during that time.
I added enough software delay after each synch interrupt to adjust for this timing in the switcher. The VTR commands were now in lock step with the video synch, so were always at the onset of the frame.
Adams went to management with a request to design a new RTC board for the PDP-11 but was told that the clock problem should be solved in software, and there was no money to develop a new board.
Fortunately, I had a good buddy Bob Gilbert who laid out the interface card artwork for CMX. I convinced him to bootleg me a board, and worked out a design from the backend of the DEC RTC board and a synch stripper circuit from one of the video engineers. This board did work its way into the Bill of Materials so all 200's and follow ons had it.
Adams’ discovery, if it had been patented, could have given the company a major revenue stream when others entered the analog editing sphere.
CMX would have been in the driver’s seat for all future video edit systems. With these issues resolved, not in software but with hardware modifications, the 200 software development proceeded nicely and was soon ready.
CMX Systems was part of Memorex’s Information Group under manager John Del Favero. He briefly mentioned the progress of the forty CMX technical, marketing and administrative personnel.
“A prototype system was substantially completed at year-end 1970 and production and marketing of the product is anticipated in early 1971.”
Del Favero’s statement was somewhat misleading. The engineering teams were trying to iron out any significant bugs in the 600 before an NAB showing, knowing that the 200 would not make the trade show.
CBS editor Howard Smith continued to trial the editing system and give the development team valuable ‘real-world’ feedback. Smith started as an editor at the Hal Roach Studios in 1935 on the "Our Gang" films for Laurel and Hardy. He continued a lengthy feature film editing career, editing films like "Breakfast at Tiffany's" then moved to CBS to cut television shows like "Gunsmoke", "Get Smart" and "Gilligan's Island".
A third-party industrial design company had completed the editing console to house the system. When the first mockup of the console was delivered there was an immediate reaction. Jerry Youngstrom recalls:
Everything about it was wrong. The slope of the desk was wrong, the slope of the monitors to the desk was wrong. It was beautiful to look at but anyone who sat at it hated it! The editors who visited from CBS, the Memorex sales people. Everyone.
Youngstrom and Bargen called Ken Ferrin to help build a new console. Bargen recalls:
Jerry Youngstrom decided that the fastest way to work out the human engineering of the new editing console was to build a full-size mockup. I went over to his house one weekend and helped him build it out of plywood in his garage and on his driveway. It had adjustable tilt and height of the desk surface, monitors, etc. and was designed on the fly.
Youngstrom recalls:
After we finished up, we hauled it the 10 miles back to CMX. Over the next few weeks the very same editors from CBS who had disliked the original console sat at the new plywood monstrosity that now housed a functional CMX 600 prototype system. Using the increments that adjusted the desk and monitors we soon had all the parameters for the industrial designers to make a new console that everyone liked to look at and use.
Bargen continues:
The new editing console won a national industrial design award that year. The names of the controls on the screens and the logic of the operations were based on conversations with film editors and observation of them cutting film. The goal was to make it as easy as possible for a film editor to operate the new system.
By March of 1971, the 600 was functional, an impressive achievement for taking a new concept to working hardware in 10 months.
CMX hired a second programmer, Steve Foreman.
Adams recalls:
Steve proved to be a very competent programmer.He quickly picked up on my design philosophy for the two systems--including no 4 byte instructions <grin>. Steve accompanied me to CBS on a number of trips to get an understanding of how things worked in the field.
Steve Foreman recalls:
My first programming task in March 1971, was on the PDP-11 to devise a table to quickly remove a disk head from the software address calculation.The NTSC disks capacity СКАЧАТЬ