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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Bits 7, 6, 5 and 4 make the first character and bits 3, 2, 1 and 0 make the second character. I would guess the data ends up in a PLL circuit elsewhere in the radio so the equal sized jumps in EPROM data would suggest that the same frequency spacing exists between each channel 10Khz, 25KHz or whatever. Then for each input state, write the output state you need, this is what the EPROM should produce on it’s data lines.

Programming File for 27C64 Eprom I’m back again – sorry for the delay, I’ve suffered from a spine problem for years, it causes unpredictable spasms that probably look quite comical to watch but having slipped and torn a muscle in my lower back the last thing I wanted was any sudden movements!

epron 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. 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 erpom EPROM data you need.

Thanks again for your help, Regards.

There will be gaps in the contents of the EPROM so don’t worry if there are empty addresses you don’t use. I’ll respond as soon as I can. I wouldn’t be too concerned about what other people perom amusing, seeking Humour in other peoples misfortune normally indicates a low self image problem. It’s better to share your questions and answers on Edaboard so we can all benefit from each others experiences.


Logic probes are usually designed to respond to very short pulses that a DVM would probably miss but in your radio the signals 276c4 DC anyway so they should give the same result. You will see distinctly different voltages on the pins and they will almost certainly be very close to 0V or 5V. This means only of the possible EPROM addresses are actually used and although not marked on the schematic, address lines A8 upward are all unused and tied to ground.

The CD can only decode decimal numbers so I’m guessing the range you can select is 27v64 00 to 99 and is BCD coded.

You might be able to use binary but it’s horribly tedious. E Channel 02 What you ask for is very easy to do, you need to think in hexadecimal though instead of decimal.

27C EPROM Technical Data

AF modulator in Transmitter what is the A? You have to repeat this for each channel eprpm the data may be different at each 27f64. What i 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.

It that is the case, and if the radio is working at the moment, I suggest you note the voltages on the EPROM outputs for each channel number you select. Thanks again for your help, Tait Bin file itself as this is what i use to burn the Eproms but will wait to see if you think this will work the way it should before i attempt to complete the file.

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.


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Measuring air gap of a magnetic core for home-wound inductors and flyback transformer 7. Bin Eprom file that we have been discussing? Will be in touch when i have had a good look with my thinking cap on.

I’m more or less upright again now so “on with the work! 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.

Thanks again for your time, Regards, Chris S.

27C64 – 27C64 64K EPROM Datasheet

Turn on power triac – proposed circuit analysis 0. When using an EPROM normal use you wouldn’t swap eprpm input digits, you keep them as they are, it’s just the odd way the Tait unit is wired that makes it necessary.

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.

It is very easy to convert the bit pattern from binary to hexadecimal. BTW – my back is much better thanks.

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. The device is a Remote Channel Change module for a Repeater rack and allows 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 low depending on the channel selected.

The problem is knowing where to stop, not where to start! Heat sinks, Perom 2: I am using “Eprom45” eprm to generate the. 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 eorom the entries in the correct rows.