OT: Electronics word

Quick question. Is there an adjective for describing a digital electronic circuit that uses ICs but no microprocessors? I thought there was, but I can't remember it.

Chris

maybe TTL is what you want?

I agree with "logic" or "digital logic". Such circuits are comprised of logic chips -- CMOS logic, TTL logic, etc etc. from one or more compatible logic "families".

A microprocessor is different than a logic chip because it requires a program to define its function. A processor or computer can certainly be contstructed using logic chips but it will also necessarily contain memory and would then be regarded as a system or at least subsystem.

Another possibility...

SSI Small scale integration MSI Medium scale integration LSI Large scale integration (usually means a microprocessor)

"Glue logic" maybe - but this is usually reserved for nuts & bolts interface logic.

Are you thinking about "Combinatorial Logic?" That refers to non- clocked pure functions like AND, OR, NOT, etc. which can be combined to create outputs which are functions of the inputs, like adders.

Discrete logic?

TTL and CMOS are descriptions of physical construction.

Dave

I've never heard such a term. Anyway the distinction isn't sharp because there are simple programmable devices like PALs, and computers were once built from gates. At Unitrode I watched the amount of logic in their analog power control ICs slowly increase until it covered most of the schematic. It's hard to draw a line at say the inclusion of an ALU and microcode because rudimentary versions of them can appear in custom logic that is considerably short of being a microprocessor. Today your power supply regulator or Lithium battery pack could include a stripped down dedicated processor.

I've designed circuits with Xilinx FPGAs and a VLSI ASIC that ranged from a simple bus address decoder to a custom dynamic RAM controller with state-machine memory and decision-making capability, specifically which competing access request to answer next without forgetting the refresh. Those user-programmable circuits which are like huge PALs with memory straddle the fence; they can perform logical computations if you want them to.

AFAIK insiders talk in specifics and outsiders seek generalized terms to categorize. Do we distinguish between a hobbyist who works only in wood and one who also shapes and cuts metal occasionally? Does sawing off a nail count?

jsw

LSI for large scale integration.

DTL, RTL anyone. :-) ...lew...

Except that these days you can slap an FPGA on a board, put a configuration file in it, and common usage will call it 'logic' -- even though the FPGA has memory in it. Sometimes, even though the FPGA configuration has a microprocessor hidden in it.

The lines are blurred.

(Note that I am only commenting on usage as I've heard it: were I a linguist I would claim that a language is what is spoken, not what the people in ivory towers say _should_ be spoken).

Tim Wescott fired this volley in news:vY2dne5AlKWF4w7RnZ2dnUVZ snipped-for-privacy@web-ster.com:

True, but a couple of common terms for such a board are "dedicated logic" and "combinatorial logic".

LLoyd

I began with gates made from 2N104 transistors, some in birdcage assemblies. A complex machine like a phase-shift modem was the size of a dishwasher, filled with cards containing two gates each. The designers really earned their pay back then, modern stuff is more complex but less clever.

So few of us made it all the way through school that the Army gave up on training techs for component-level troubleshooting of that equipment. The four (of ~100) in my graduating class all had science degrees.

jsw

The adjectives for the two sides of that issue are "prescriptive" and "descriptive".

jsw

Combinatorial logic.

Glue logic is usually describes the gates between a microprocessor and something else. I'd use the term "random logic" (kind of an oxymoron) to describe a logically functioning set of parts without a processor.

A gate array, field programmable or not, certainly is a logic circuit.

Especially in a case like this, where common usage evolves fairly rapidly.

I thought about that too, but this excludes common chips like dual-rank flipflops.