Texas Instruments 74LS Logic Comparators are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas Instruments . December INTEGRATED CIRCUITS. 74HC/HCT 8-bit magnitude comparator. For a complete data sheet, please also download. Part Number: 74LS, Maunfacturer: National Semiconductor, Part Family: 74, File type: PDF, Document: Datasheet – semiconductor.

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I’m not that good with circuit design, but is it adtasheet a monostable multivibrator one-shot would do the job? I got lost reading that. A way to avoid that would be to de-glitch the circuit by adding a synchronizing flip-flop running at 16MHz just before the latching flip-flop. This might cause a false trigger if your address trap was at B.

74LS688 Datasheet

There may be better ways to do this job so keep tinkering. Just to scratch my own curious itch, what does the connect to? This would also add about 62 nS to your latch clock which right now is only 3 gate delays long and would be difficult to see on an old low bandwidth scope. It might work, but I don’t like it much. It’s an 8-bit comparator, but it’s cheaper than the 74LS85 datsaheet has an enable input.


In other words, what function does it serve?

My calculations say yes, with lots of time to spare, but I’d like others’ opinions. I’m datasheet talking about little tiny noise spikes. Any decoder, like the will create big nasty full swing glitches that can only be removed with the proper clocked gating or latching. Glitchy output shouldn’t be a problem — glitch, I see how you got your nickname. I’ve never had to use one.

It may even make it worse. You could then use it as a clock. Note that this would take away 62 nS from the 74lx688 time of the first instruction fetch after the proper address compare, but it should be OK if you are using newer memory devices.

Glitchy output shouldn’t be a problem — it needs to be inverted for the D-type flip flop’s clock anyway, so I’m using a 74LS14 inverter, which has Schmitt inputs and should clean up the signal into a nice, sharp positive-going square wave. You can’t use it while the inputs are changing. I’m currently designing the power-on-jump circuit for my processor board.

Comparator 74LS688 DIP20

Here’s the pieces relevant to Power on Jump: This is all fine. I don’t do well with word descriptions of circuits–can you draw a schematic? Hi No it won’t. When the system comes up from a reset, a 74LS with its inputs all tied to ground is connected to the data lines of the CPU and the data bus tranceivers are switched datasheet — this feeds the CPU NOPs until the address equals what’s set on the DIP switch.


Propagation delay question [Archive] – Vintage Computer Forum

You’re depending too much on the propagation delay of the 74 and the creating a clock pulse of the minimum required width t wclk on your datasheet. This sets the Datasyeet flip flop, which switches off the NOP generator and turns on the bus tranceivers. It’s comparing the high four address bits to a 4-position DIP switch. As the address lines transition and settle out, they might very 74os688 set up a glitch that agrees with the test condition, well before you intended.

Hi I doubt you’ll be able to run the output of the directly to a clock.

It is a glitchy signal. If you expect to use it, you need to turn the enable off during the time when the compare inputs are in transition. For example, going from 9 to A might give a false compare of B for a few nanoseconds.