Stumbled on this forum last year while I was in c++. Unfortunately, I am now completely surrendering myself to your guys input, because I am truly out of breath and energy to push through any further with my lab project.

Here is my class' project objective:

--Design and implement the hardware and software of a simple EEPROM programmer with common TTL IC's that are mostly available. The EEPROM program is designed to connect to a standard PC's parallel printer port and work independent of processors speed. An assembly program to read and write data from/to the EEPROM programmer from a PC is also to be developed.

I have hard wired a schematic, using the following devices:

32Kx8 EEPROm ( ATC28C256)
4 74LS374
74LS257 Mux
74LS138 Decoder
Printer Cable DB25

the DB25
-- Base +0 address will be used to send output data that are used as address signals to EEPROM, data to EEPROM, and control signals to EEPROM

--BASE+1 address will be used to read 4-bit data from EEPROM

--BASE+2 address will be used to send 4-bit output to use as control and input signals of 74LS138 and select signals to 74LS257 MUX


the hardwiring is pretty much taken care because we were given a general schematic and I have completed the actual wiring on my breadboard.

However, using the DOS system, I am completely stuck on how to read,write to the EEPROM. Data is to be verified correct, in our case , I will be using LED's.

But if you guys can figure a way to use DOS to read/write through the DB25, I am open to ideas.

I have spent the last few days trying to get this work, and have always failed at writing the assembly program.


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