Mikahn Beware though, as many modern ones will not handle the smaller capacity ICs like the and ones found in very old microcomputers. This is why the ICs have a clear window in them; to allow the UV light to penetrate and erase the data. How reliable is it? An insulating layer of oxide is grown over the channel, then a conductive silicon or aluminum gate electrode is deposited, and a further thick layer of oxide is deposited over the gate electrode.
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Q7 is used to sharpen the rising edge of the clock signal and will not harm the Texas HC or the LS chips so to be safe you can always install Q7 and use a R resistor. Everything will still work and omitting Q7 only saves 40 cents. The size of the PCB was kept small enough to fit onto one of the standard x 74mm boards that are available throughout Australia. PCB can be downloaded here. Testing After you have finished constructing the programmer plug it into an AC plug pack 12VAC is specified but a 9VAC unit will work and the heat sinks will run cooler.
Also check that there is no more than about 5 volts on any of the pins on the 26 way header. You will be shown a screen that looks like this though not all the lines will be there yet.
When the software is first run it will test the counter and the data lines. VCC is the pin in the top right hand corner of the 28 pin socket. After this VPP needs to be checked. Put the switch in the UP position and VPP will be the pin in the top left hand corner of the 28 pin socket.
However it is not Freeware. It is a slightly different concept called Great-Guy-Ware. All you have to do if you wish to use the software is send me an E-mail telling me I am a great guy. This serves two main purposes. One is to make me feel good and secondly it encourages me to finish some of the other articles I may have started in the last ten years.
The software is contained in the main zip file eprom. Its is also available by itself software.
The transparent lid allows the user to expose the chip to ultraviolet light to erase the bit pattern. A new pattern can then be written to the device by following the programming procedure. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability.
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