2x 27c4001 onto 27c801

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I'm pretty sure I've done it before, but just case I forgot how to do it.
Am I correct in that you can put two bin files from a 27c4001 into a 27c801 by combining the files and then you should be able to control which half of the 801 is accessed by grounding pin 1 or not?
 
If your 2 4Meg files are named "file1.bin" and "file2.bin"

open a command prompt in the folder contain the two files and use this command...

copy /b file1.bin + file2.bin file3.bin

This will create a new file named "file3.bin which will be 8Meg in size.

you then toggle pin-1 (A19) to select the lower or upper half of the EPROM.
 
I pretty much did that, but for the life of me its still not accessing the second half of the 801 when I ground pin 1. I opened the bin file in a hex editor and copy and pasted the second bin file at the end of the first. same result.
 
Are you pulling it high when you're not grounding it? Either by using a SPDT switch switching VCC and GND, or by using a pullup resistor and a SPST switch to GND the pin? And the "bottom" half of the ROM will be accessed when the pin is grounded, the "top" half when the pin is connected to VCC.

DogP
 
Are you pulling it high when you're not grounding it? Either by using a SPDT switch switching VCC and GND, or by using a pullup resistor and a SPST switch to GND the pin? And the "bottom" half of the ROM will be accessed when the pin is grounded, the "top" half when the pin is connected to VCC.

DogP

Yea I'm using a pullup resistor and the top half boots fine, its just the bottom half I cant get to work. I guess Ill redo the files and reburn them and see what happens
 
Oh, and are you lifting pin 1 out of the socket, or otherwise making sure the PCB isn't driving the pin? If it's meant for a 27C4001, pin 1 would be connected to either GND or VCC on the board.

DogP
 
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