Re: Delay Time Position Vernier

Dave Wright

When I was a pup in the emerging field of digital data storage and field recorders, I was presented with a 465B for my bench. I remember staring at it for a minute or so, until the senior tech reached over and pulled on the power knob. I still hadn't found it...

Learned to love the 465, and still have the refurb one I bought with a loan from Grandma in the previous century, $2K

The data recorder (prefer not to say what it recorded...) used dynamic RAM with a 1mS refresh rate, and a 250 nS read cycle. Running the scope at 100 uS / Div on RAM clock the gave you a nice parade of closely spaced pulses at the left side of the screen, and over at the right side you might see the beginning of the next refresh cycle if the clock crystal in the recorder was off a bit. We would use the B-Delayed sweep to slowly scroll through the sequential addresses to the RAM, and thereby be able to see any desired address of the lower 8 bits of the bus as the address incremented.

Pretty much a similar use case as with analog TV, the variable delay allowing you to scroll to a particular line, or portion of a line, in the video scan...

_Dave KC6UPS

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