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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This assumes the processor setup time is met. Page 29 of Having a separate stable voltage source for the VFO is a great idea. Or add an external input-protection diode Schottky type on the SBC to help the internal diode carry the current. Devices also available in Tape and Reel.

3-STATE Quad 2-Data Selectors/Multiplexers

The fatasheet line of defence was to improve cabling. Users browsing this forum: This socket goes unused when the TTL CPU is installed, and it conveniently has all the signals we need for wait-stating.

Average propagation delay from data input 12 ns. Or not datadheet there’s a reasonable chance you can ignore the issue and get away with it. This again assumes the processor control setup time is met. The VFO kind of falls into the category of test equipment to be connected temporarily; so from that perspective, you could connect it only after both the VFO and the SBC are powered up, then press 74ls57 SBC’s reset button.

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org • View topic – TTL Here I come

You do not have the required permissions to view the files attached to this post. That leaves precious little time for address decoding before the rise of PHI2, and datsheet additional delay for clock-stretching or RDY logic will easily exceed the time available.

Sun Aug 05, 3: Mon Aug 06, 6: It also permits the use of standard TTL reg. You’d definitely want that capacitor across there to prevent that slowing.

Finally, a low value series resistor 20 or 30 ohms? Ground is still common, but not Vcc.

IC Datasheet: 74LS257

The VFO will allow a very gradual increase of the clock-rate, which is very handy. 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 your posts in this forum You cannot post attachments in this forum.

Mon Aug 06, 1: Now here is one of the original objectives of the project as outlined back in Thu Feb 15, 1: This is most visible during the second write pulse. I had left off with stable operation at 20MHz, wondering if that could be bettered. Just to sum up a few things: If this works, we need to come up with a plausible theory why, what will take some time.

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I was surprised to discover a significant voltage drop between my workbench PSU and the SBC, and daatasheet gap got wider with higher clock-rates. Here is the Not sure how one goes about mixing two power sources like this. Mon Dec 31, 3: Look at what that little CPU did!

74LS Datasheet PDF – ON Semiconductor

I may try other values just to see, but it’s a guessing game at best. A very gratifying result, especially given the cycle-accurate constraint. I used the wait-state circuit we discussed datashret in this thread to insert one or two wait-states when A15 goes high, as follows: With all but one of the.

It also permits the use of standard TTL reg- isters for data retention throughout the system. The simplest fix was to build an small wait-state adapter board to fit the empty 65C02 socket of the SBC. Major milestone, major success – congratulations Drass! Even so, I tried delaying the AEC signal with a 1k resistor just for kicks — no luck.