spec , Big respect but you meant NAND of courseIncidentally, the first 74 series logic chip was the 7400 which is a QUAD TWO INPUT NOR GATE. As this chip has both the fundamental functions in one gate, it follows that you can make any binary function with a number of 7400 chips. In fact, that is pretty much what is inside the counter chips.
Hy John,
I can tell that you are intrigue by digital electronics and are somewhat mystified by it- as I was when the first digital chips became freely available in the 1960s.
To answer one of you questions- yes, to make a counter, only binary is involved (other digital states, most notably ternary, can be used but are rare).
For the most common binary logic family, the 74 series transistor transistor logic (TTL) family, a logic 1 is 5V and a logic 0 is 0V (this is not exactly true, but just assume so). The other thing to know is that you can make every logic function from a simple counter to a microprocessor to a gigabyte memory with just two fundamental logic functions: NOR (invert) and a two input gate, either AND or OR, assuming an unlimited number of those functions that is.
You ask how does a counter know how to count. The answer is because a fairly large number of the two fundamental binary functions are hard wired to do so using digital, binary design techniques
Once you get the hang of it, making a counter from the two fundamental binary logic functions is quite straight forward.
Incidentally, the first 74 series logic chip was the 7400 which is a QUAD TWO INPUT NOR GATE. As this chip has both the fundamental functions in one gate, it follows that you can make any binary function with a number of 7400 chips. In fact, that is pretty much what is inside the counter chips.
spec
Thanks grand- as I said before, I make mistakes all the time, but I try to keep them big so they are obviousspec , Big respect but you meant NAND of course
Not really following,the 4026 is basically a bunch of logic gates?
So the 4026 is made of a number of 7400 chips?
and when a certain voltage is meant it goes high meaning numbers increment by one as each output goes high due to a high voltage?
No probs John- my pleasurespec
You have been a great help, thanks for your contribution it is very detailed.
I cut my teeth as it were on SN74 TTL , although my projects were a bit of a rats nest , this was my early attempt at a MiDi interface for a 2 manual ELKA organ ,( HC and LS chips) my favourite IC however was the 8255 here it scanned the 132 note keys, in about 5 msec. CDP6402 if I remember is a composite video display driver, the board hung on to a Maplins Z80 development board... as a note I could not have done it without a scope. …. great fun ..
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That made me smile- fond memories of similar boards. The first biggy was a hand-wired rip-off of the PC that preceded the BBC computer, the Acorn Atom.
6402 CPU and 8255 parallel IO controller- great fun as you say.
spec
You willI wish I knew what you guys were talking about!
I learned logic with:Maybe I am older than you guys. I learned logic with RTL, then DTL, then TTL, then LS-TTL then I threw away my TTL Cookbook and used Cmos then HC-Cmos for all logic circuits I designed.
Do you remember those wire wrap back planes- looked like a rats nest.I updated office computers a long time ago. The operating system was punched cards and the RAM memory was thousands of tiny donuts of ferrite hanging on a maze of wires. No pcb, everything was wire wrapped on millions of square pins. I fixed a problem by piggy-backing a DTL logic IC on top of another DTL IC.
Eh By Gum, these young lads don't know they are born these days. None of this integrated circuit stuff when I were a lad. We had to build gates, flip flops, counters etc, out of resistors, capacitors, diodes, and transistors. Not only that, but we had to mine and smelt the lead and tin for our solder ourselves. I used to get up before going to bed, run twenty miles to work, come rain hail and snow, designing circuits all the way. Then get reported by the guard room for being late for the five am shift. There was tombs of information to wade thru about speeding up transistors, steering diodes and all sorts of stuff like that. To get flip flops to toggle at 1Mhz was a sweat.John , you may have noticed your 'simple question' has turned into a trip down memory laneFor me in the early days engineers had to concentrate hard on logic, and testing etc referring to massive circuit diagram books ( 50 pages of A3 or even A2 was common ) it must have burnt into our brains.
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