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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The “External Interface” on the left Hand top is where the Channel Change eprom output connects to directly and you can manually select any of the channels that have been previously programmed via the Tait Software into the radio’s own Eprom, via the 8 DIP switches.

There will be gaps in the contents of the EPROM so don’t worry if there are empty addresses you don’t use. It makes reading and writing a bit difficult. Thanks again for your time, Regards, Chris S. Glad you are feeling a bit more comfortable, i have hurt my back before and i know just what it feels like.

27C64 – 27C64 64K EPROM Datasheet

I have the data for the Channel Change Eprom prepared but still have to spend more time on the Programming software to be clear about where to place the entries in the correct rows.

I worded that badly, not sure now what info i need so that the Eprom can decide which output lines to pull low Ground Apologies. Programming File for 27C64 Eprom Hello, Was wondering if someone that has had some experience in creating a BIN or HEX file suitable for a 27C64 Eprom could point me in the right direction re creating a file that would allow the above Eprom to control the output of its data lines D0 – D7 so that it will switch the lines either high or Low i.

Part and Inventory Search. After a while, when you have got used to thinking in hexadecimal it all falls into place, it’s easier than it looks.

How reliable is it?

You might be able to use binary but it’s horribly tedious. I am using “Eprom45” buffer to generate the.


If I understand what you want, you have known input lines states and you want to convert them to different output line states by using the EPROM as a look-up table. A logic probe and DVM should tell you the same result so it’s up to eprok which you use.

The on the third schematic is periodicaly pulsing the latch signal so the switches are read in. Programming File for 27C64 Eprom It is possible for data to be duplicated and I epro expect the vast majority of the addresses to be empty in this kind of application. Would you know why this is i tried redoing this several times and the result came out the same?

You will see distinctly different voltages on the epfom and they will almost certainly be very close to 0V or 5V. If you know the channel frequencies it should be easy to work out, it’s likely that a change of one count in the EPROM data makes a difference of one channel frequency so if you know what the channels are, it should be simple math to reverse engineer it back to the EPROM data you need.

I have printed out your reply and will study it tonight in detail when i can concentrate on it fully.

Programming File for 27C64 Eprom

E Channel 02 I have a circuit Diagram of the unit and the input to the Eprom is already there with the BCD switching done by a pair of chips. Each of the 4 bit patterns is translated to a single hexadecimal character like this: The device is a Remote Channel Change module for a Repeater rack and eprpm remote selection of channels in the TX and Rx modules by pulling various data lines in the same chip installed in the modules either high or 27c644 depending on the channel selected.

For example if the input lines were the address is C and you wanted to output on the data lines the value to place in C would be 9B. I don’t know if this is correct and would be very grateful if you could point out any mistakes in my file as it does not look like any. Epom Eprom file that we have been discussing?


27C EPROM Technical Data

I assume the outputs from the EPROM are connected to the inputs of a PLL circuit so that different frequencies are selected for each combination of logic state. I am not fluent with Eprom programming and i have probably messed up the conversion from Binary to hex or placed it in the wrong location.

This is exactly what is required, the Thumbwheel switches generate the line states from a Numerical setting 01,02,- 99, etc and the module displays these on the 7 seg Leds and switches the output lines to match, controlling the Radio Modules.

I would eprmo very grateful for any further assistance you might be able to provide on the above. Apologies for the long first post but if anyone could point me the right direction as to how to create this file i would be most grateful before i wear out my UV Eraser or the Spare Eproms i have been using to test the files Regards. Usually in this scenario, the bits are used to set the division ratio in a PLL controlled oscillator and hence the frequency it is tuned to.

I have the Eproms for the TX and RX modules correctly burned with programming files provided by the equipment manufacturer Tait but i am lost as to how to create a BIN or Hex file from scratch to get the Channel Change Eprom to output the correct switching via its Data erpom lines.

Programming File for 27C64 Eprom Thanks Brian, Looks as though i might have to stick with the Eprom Idea for a bit longer, i have a few spare 27c64 available that i think are still good. If i 27c664 to select 01 on the Pushbutton switches how would that 27c46 to the input states of the Eprom data lines?