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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If the VFO output is strong enough it’ll exceed the fairly tiny current-carrying capability of the input-protection diode and destroy it.

I had left off with stable operation at 20MHz, wondering if that could be bettered. The problem was entirely the result of a silly error. That allows plenty of time, in fact, and this circuit requires only a single gate delay between address logic and RDY, 74ps257 is about as crisp as you can get. Average propagation delay from data input 12 ns. Ok, back to more testing with the C64! Congratulations to your success!!

If there’s a doubt though, note that if you use only ohms, a logic output of nearly 5V, minus a Schottky diode drop, divided by ohms is still over 40mA; so I would make it perhaps ohms, and put a 47pF or pF across that resistor so the slew rate at the load doesn’t get too slow. The game is called Neoclypssort of a homage to Defender on the C Not sure vatasheet one goes about mixing two power sources like this.


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Even so, I tried delaying the AEC signal with a 1k resistor just for kicks — no luck. The VFO will be used seldom enough that it should be practical to give it its own 9V battery and a 78L05 regulator or even an adjustable LML both being in a small TO packageso it won’t be affected by the computer’s power-supply voltage.

You do not have the required permissions to view the files attached to this post. Sun Aug 05, 4: It was a bug, and one that had gone unnoticed to this point. Having multiple power supplies is common although not so much with circuits.

Sun Aug 05, 3: Look at what that little CPU did!

Datashet definitely want that capacitor across there to prevent that slowing. I used the wait-state circuit we discussed earlier in this thread to insert one or two wait-states when A15 goes high, as follows: Now that seems like a lot of work and trouble for just 1 MHz above the previous record, but so be it.

Ground is still common, but not Vcc. That leaves precious little time for address decoding before the rise of PHI2, and any additional delay for clock-stretching or RDY logic will easily exceed the time available. The VFO will allow a very gradual increase of the clock-rate, which is very handy. Schottky-clamped for significant improvement in A-C. From the datasheet, 82S propagation delay input to output is 35ns typ.


3-STATE Quad 2-Data Selectors/Multiplexers

To minimize the pos. Major milestone, major success – congratulations Drass! Finally, a low value series resistor 20 or 30 ohms?

Users browsing this forum: A very gratifying result, especially given the cycle-accurate constraint. It also permits the use of standard TTL reg. Page 29 of I say nearly because I see slight differences between them, several of which are 10ns variations, and may simply be artifacts of the sampling rate Mhz.

Thu Feb 15, 1: This socket goes unused when the TTL CPU is installed, and it conveniently has all the signals we need for wait-stating.

Provides bus interface from multiple sources in. This 74l2s57 output feature means that n-bit paralleled data selectors with up to sources can be implemented for data buses.

The C64 booted without a problem. Mon Aug 06, 6: TTL Here I come.

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