Test equipment having digital displays and no CPU control

[japlytic]

When I was investigating the National Panasonic VP-8177A signal generator (with digital frequency and option displays), I was suprised that it had no microprocessor control, but it did have a battery-backed Intel 5101L 256*4 bit SRAM (separate input and output buses) for memory (I devised a simple 3-chip circuit with commonly available ICs to make it work with a modern bidirectional bus SRAM).

Another example of test equipment with digital displays without microprocessor control include a 600MHz frequency counter (1984 ARRL article).

I've seen video arcade machines without microprocessor control (discrete logic, no CPU or PLDs including ROMs) from the early 70s, most notably Atari's Pong.

I am curious, but are there oscilloscopes with on-screen character displays without microprocessor control, or even digital voltmeters without microprocessor control?

[Agent24]

Re: Test equipment having digital displays and no CPU control

No idea, but you can make a game of pong without a microcontroller of any sort:

http://www.electronixandmore.com/pro...ong/index.html


Edit: I should learn to READ.

[hardwareguy]

Re: Test equipment having digital displays and no CPU control

Some of the big benchtop DMMs from the early 70s using nixie tubes likely have discrete logic.

I need to take apart that big HP DMM at my friends lab....it's so ancient that it uses 7 segment displays that use multiple LEDs per segment as the LEDs at the time weren't bright enough to allow one LED to light an entire segment. It was probably an obscenely expensive instrument.

[Agent24]

Re: Test equipment having digital displays and no CPU control

The capacitance meter I built runs all on standard logic ICs, with a 4-digit display using 7-segment LEDs

I posted the design here somewhere... (it's from 1990!)

[tom66]

Re: Test equipment having digital displays and no CPU control

Most digital multimeters these days don't use a microcontroller, they have an ASIC/ASSP chip which integrates an ADC and display driver. Even the fancy features like frequency counters and cap testing are done entirely in logic, although on one piece of silicon.

[Longbow]

Re: Test equipment having digital displays and no CPU control

Not everything needs to be controlled by a CPU. ASIC's are more practical and faster for specific applications. Why would a freq. counter need a CPU? All it needs is a stable reference oscillator, a counter and a display. The simpler the design, the more likely you can fix it when it breaks.