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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Just to sum up a few things: If this works, we need to come up dxtasheet a plausible theory why, what will take some time.

This assumes the processor setup time is met. Thanks for all the comments Dieter!

Now here is one of the original objectives of the project as outlined back in Look at what that little CPU did! You’d definitely want that capacitor across there to prevent that slowing. This again datasyeet the processor control setup time is met. I had left 74ls275 with stable operation at 20MHz, wondering if that could be bettered. With all but one of the common outputs disabled at a high impedance statethe low impedance of the single enabled output will drive the bus line to a HIGH or LOW logic level.

Now that seems like a lot of work and trouble for just 1 MHz above the previous record, but so be it. The C64 booted without a problem. TTL Here I come.


74LS Datasheet Hitachi Semiconductor pdf data sheet FREE from

With all but one of the. Having multiple power supplies is common although not so much with circuits. Anytime the VFO power supply is substantially higher than the SBC power supply which could happen during powerup or powerdown you can encounter unexpected current flow. Not sure how one goes about mixing two power sources like this.

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

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. All voltages are referenced to ground though, and a DMM would show zero ohms from any ground pin to any other ground pin. datashewt

IC Datasheet: 74LS257

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.


I used the wait-state circuit we discussed earlier in this thread to insert one or two wait-states datashret A15 goes high, as follows: This results in a potential threat which you may choose to address.

You do not have the required permissions to view the files attached to this post. The simplest fix was to build an small wait-state adapter board to fit the empty 65C02 socket of the SBC.

74LS Datasheet PDF – ON Semiconductor

Cheers for now, Drass You do not have the required permissions to view the files datasgeet to this post. The problem was entirely the result of a silly error. That leaves precious little time for address decoding before the rise of PHI2, dstasheet any additional delay for clock-stretching or RDY logic will easily exceed the time available. It also permits the use of standard TTL reg- isters for data retention throughout the system.

This is most visible during the second write pulse. A very gratifying result, especially given the cycle-accurate constraint.

Select a forum Let’s say the load were 30pF. Previous topic Next topic.

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