Stored Code? Real Men Use Logic Gates, Flip Flops, Diodes and Transistors
Posted: Sat Feb 16, 2019 9:41 pm
Yeah, like using a 20 MIPS processor requiring an FCC Class-B certification to embed into a product to do the work of a diode, resistor, and capacitor. Something like that.
Call me a digital Ludite but today, somehow, I got reminded that my first large-scale DIY project was digital and required building clocked logic using resistor-transistor-logic flip-flops and gates.
That was 1970.
I didn't discover op amps until 1973...
Today writing code and requiring a million transistors in a large scale IC someone else made to do the same thing seems like the work of a hipster soy boy pussy. Like the Arduino clock I did
This is how real men do digital:
Sometime between 1969 and 1970 I became interested in building a digital clock.
I was about 12 at the time and began sketching clock circuits using J-K flip flop dividers.
I am "clock boy."
My brother had some surplus RTL (resistor transistor logic) ICs mounted on circuit cards.
I was able to buy some Amperex ZM-1000 "Nixie" display tubes and some Fairchild BCD to Decimal HV driver ICs.
The ICs are mostly MC790P J-K flip flops, some MC789 inverters and a couple of misc gates.
All-in-all there are 19 ICs. (One is underneath on a Veroboard).
I wanted a small display so a multiconductor cable was used to link the "base" logic unit to the display head.
The display sat on my headboard with the clock stashed under the bed.
This was my first major electronics project.
Looking back on it almost 50 years later I realize the logic design was pretty solid.
The execution sucked - but hey - it was my first project and I was 12.
My Dad gets credit for the solid walnut case.
The clock display unit has three Amperex ZM-1000 "Nixie" displays. The hours "1" is a long neon.
The clock base unit uses 19 RTL (resistor transistor logic) ICs mounted on individual plug-in cards.
Most of the ICs are Motorola MC700-series RTL. A CMOS IC was installed "dead-bug" sometime in the 1980s due to failure.
Once I got a couple of Heathkit clocks I retired this unit.
It sat under my father's workbench for years absorbing sawdust, oil and dryer lint.
Sometime in the late 1980s or early 1990's I began phase one of the restoration replacing the 2N3055 regulator with a LM317.
An RTL IC failed and I had to cobble a dead-bug CMOS chip.
I later gave up because I realized it had become an unreliable pig.
The edgecards had became flakey and I didn't want to clean them and the receptacles.
The clock set in the garage and was later moved to the basement.
I decided, almost 50 years later to rescue it.
It took a can of Blue shower, a can of duster and a re-cap to bring it back to life.
Glad I did though.