The Microchip Technology Inc. 27C64 is a CMOS 64K bit (electrically) Programmable Read Only Memory. The device is organized as 8K words. 27C64 64k (8k X 8) CMOS EPROM FEATURES. High speed performance ns access time available CMOS Technology for low power consumption 20 mA. 27C64 EPROM Datasheet, 27C64 64K EPROM Datasheet, buy 27C

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Programming File for 27C64 Eprom It’s a strange system, if if the date is difficult to read it was well into the era of microprocessors so using so much discrete logic seems a bit backwards. I am not fluent with Eprom programming and i have probably messed up the 2c764 from Binary to hex or placed it in the wrong location. It would be useful to note this because you may be able to use it to calculate new channel frequencies.

Bin Eprom file that we have been discussing? Synthesized tuning, Part 2: For example, if you wanted EPROM channel 10 to produce an output of you would first reverse the channel digits and use address 01, then split the 8 bit output you want into two becomes then convert each to hexadecimal to find the number to store in the EPROM.

BTW – epom back is much better thanks. You will see distinctly different voltages on the pins and they will almost certainly be very close to 0V or 5V.

Programming File for 27C64 Eprom Got them thanks. I wouldn’t be too concerned about what other people find amusing, seeking Humour in other peoples misfortune normally indicates a low self image problem. Thanks again for your help, Regards.

I’m suspicious of the maximum voltage for logic 1 being 2. E Channel 02 What 27×64 would like to do is check that the unit is sending the correct signals via the Data lines to switch the Eprom on the Radio Channel Board to select the correct channel.


This then gives me a set of ascending Location Numbers for the data and and what looks like descending data to go in those locations. Logic probes are usually designed to respond to very short pulses that a DVM would probably miss but in your radio the signals are DC anyway so they should give the same result.

Programming File for 27C64 Eprom. I am using “Eprom45” buffer to 27d64 the. I assume the outputs from the EPROM are connected to the inputs of a PLL circuit so that different frequencies 2764 selected for each combination of logic state.

If this is true would i be able to measure with a DVM on DC volts the output state of the data lines out of the Channel Change eprom to confirm i have the correct lines either high or low to replicate the Dip switch settings on the Radio Eprom Board?

Distorted Sine output from Transformer 8. The Channel Change module runs on 12V DC fed from the rack supply and if i can use this to power the Logic probe would this give me the ground signal for the probe to check the status of the lines?

When you have done it for all the input combinations you need, program the chip. It makes reading and writing a bit difficult.

Programming File for 27C64 Eprom

Hierarchical block is unconnected 3. Would you have a minute to take a look at a file i have produced in regards this. Last edited by tait ; 22nd April at After i asked you about using the DVM to check whether the output lines were at the correct Logic level i suddenly remembered i had a Logic Probe from when i was at tech, this is powered from its own Batt supply but do i have to tap into the Neg Supply on the circuit to get a ground signal for the probe to work?

Then for each input state, write the output state you need, this is what the EPROM should produce on it’s data lines.

I have a rather old but still functional FRG receiver here which is crying out for a revised processor board, especially as the original has some serious bugs in it’s software. Would it be possible for you to take a quick look and tell me where, looking at the diagram i would enter the data to have “01” selected on the Push Buttons and have “DO” pin 11 pulled low on the Eprom output?


Turn on power triac – proposed circuit analysis 0. Bin 2c64 i have seen before. If you think this is correct i will go ahead and load the File onto a new Eprom and see how we go but i thought i might check with you first. I would be very grateful for any further assistance you might be able to provide on the above. I’m more or less upright again now so “on with the work! Similar Threads Eprom programming help 8. The CD can only decode decimal numbers so I’m guessing the range you can select is from 00 to epron and is BCD coded.

In other words anything higher than 2. Eprlm of the strange way the EPROM address pins are connected, the input digits are reversed so if you want channel 10 you use address 01 instead.

I have the circuit below of the Channel Change module that describes how the output of the Two Pushbutton switches are latched and then feed the 27C64 inputs but i am unsure what input location to start from, I.

27C64 – 27C64 64K EPROM Datasheet

The problem is knowing where to stop, not where to start! Digital multimeter appears to have measured voltages lower than expected. I have printed out your reply and will study it tonight in detail when i can concentrate on it fully. Last edited by tait ; 21st April at Glad you are feeling a bit more comfortable, i have hurt my back before and i know just what it feels like.