June 3, 2020   |   by admin

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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Sierra IC Inc

This sets the D-type flip flop, which switches off the NOP generator and turns on the bus tranceivers. I’m not that good with circuit design, but is it possible a monostable multivibrator one-shot would do the job?

Any decoder, like the will create big nasty full swing glitches that can only be removed with the dtaasheet clocked gating or latching. I’m not talking about little tiny noise spikes.

datasheeh Glitchy output shouldn’t be a problem — glitch, I see how you got your nickname. I got lost reading that. It is a glitchy signal. I’ve never had to use one.

Comparator 74LS688 DIP20

There may be better ways to do this job so keep tinkering. Note that this would take away 62 nS from the access 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, datxsheet positive-going square wave.


Here’s the pieces relevant to Power on Jump: I’m currently designing the power-on-jump circuit for my processor 74ld688. This is all fine. It may even catasheet it worse. 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 off — this feeds the CPU NOPs until the address equals what’s set on the DIP switch.

It’s comparing the high datsheet address bits to a 4-position DIP switch.

74LS Datasheet PDF –

It’s an 8-bit comparator, but it’s cheaper than the 74LS85 and has an enable input. My calculations say yes, with lots of time to spare, but I’d like others’ opinions. dataeheet

In other words, what function does it serve? For example, going from 9 to A might give a false compare of B for a few nanoseconds.

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.

Hi No it won’t. You can’t use it while the inputs are changing. Just to scratch my own curious itch, what does the connect to? As the address lines transition and settle out, they might datwsheet well set up a glitch that agrees with the test condition, datsheet before you intended.



This might cause a false trigger if your address trap was at B. You could then use it as a clock.

Hi I doubt you’ll be able to run the output of the directly to a clock. 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. I don’t do well with word descriptions of circuits–can you draw a schematic?

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. If you expect to use it, you need to turn the enable off during the time when the compare inputs are in transition. It might work, but I don’t like it much.