74LS257 DATASHEET PDF

74LS datasheet, 74LS pdf, 74LS data sheet, datasheet, data sheet, pdf, Fairchild Semiconductor, 3-STATE Quad 2-Data Selectors/Multiplexers. These Schottky-clamped high-performance multiplexers feature 3-STATE outputs that can interface directly with data lines of bus-organized systems. With all but. 74LS datasheet, 74LS circuit, 74LS data sheet: FAIRCHILD – 3- STATE Quad 2-Data Selectors/Multiplexers,alldatasheet, datasheet, Datasheet.

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Got the timing parameters for 74xx chips from there: This 3-STATE output feature means that n-bit paralleled data selectors with up to sources can be implemented for data buses. I was surprised to discover a significant voltage drop between my workbench PSU and the SBC, and the gap got wider with higher clock-rates. Mon Aug 06, 8: Thanks for all the comments Dieter!

Even so, Dagasheet tried datawheet the AEC signal with a 1k resistor just for kicks — no luck. This is most visible during the second write pulse. Congratulations on the success! Cheers for now, Drass You do not have the required permissions to view the files attached to this post.

This results in 74sl257 potential threat which you may choose to address.

That allows plenty of time, in fact, and this circuit requires only a single gate delay between address logic and RDY, which is about as crisp as you can get. That helped narrow the voltage gap, so I felt the CPU was more easily datashfet draw the additional power it requires at high clock-rates. This assumes the processor setup time is met. Mon Feb 19, All voltages are referenced to ground though, and a DMM would show zero ohms from any ground pin to any other ground pin.

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I had left off with stable operation at 20MHz, wondering if that could be bettered.

74LS Datasheet PDF – ON Semiconductor

Let’s say the load were 30pF. Users browsing this forum: A very gratifying result, especially given the cycle-accurate constraint. It turns out RDY took effect one cycle too late! Thu Feb 15, 1: Finally, a low value series resistor 20 or datashfet ohms? I tested the circuit with the 65C02 on a breadboard and it worked perfectly.

Now here is one of the original objectives of the project as outlined back in If this fails, we need to come up with a plausible theory why, what will take some time. I used the wait-state circuit we discussed earlier in this thread to insert 74ls2557 or two wait-states when A15 goes high, as follows: Or add an external input-protection diode Schottky type on the SBC to help the internal diode carry the current.

I say nearly because I see slight differences 7ls257 them, several of which are 10ns variations, and may simply be artifacts of the sampling rate Mhz.

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74LS Datasheet Hitachi Semiconductor pdf data sheet FREE from

Having verified proper operation of the RDY circuit, and other preparations having been made, it was time for the big moment From the datasheet, 82S propagation delay input to output is 35ns typ. The simplest fix was to build an small wait-state adapter board to fit the empty 65C02 socket of the SBC. Just to sum up a few things: This again assumes the processor control setup time is met.

You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete dataeheet posts in this forum You cannot post attachments in this forum. Congratulations to your success!!

Select a forum Mon Aug 06, 6: I do see the address lines reacting more quickly after AEC changes state. Devices also available in Tape and Reel.

74LS257 Datasheet

Provides bus interface from multiple sources in. Fri Feb 16, 8: Previous topic Next topic. Average propagation delay from data input 12 ns.

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