So I finally got my 4-Bit CPU working on Logisim, and am trying to get it to do commands and display them, but am unable to do so. My CPU looks like the following:
I am trying to implement the following commands or opcodes into the Decoder (Address Bit Width = 4, Data Bit Width = 8):
And my PROM (Address Bit Width = 4, Data Bit Width = 16) Gives an output as follows:
Question 1: How do I create a simple program following these guidelines that will take 3 + 4 and add them, displaying each number, digit and symbol, as well as the result. (I.e. What goes in decoder, and what in the PROM?)
Question 2: How do I figure out how to display simple letters on the display? (I want to type Hello World).
I'm not much of a low-level programmer, but understand the concepts so help would be appreciated.
I have a file named Hello.txt which can be used to load a program into the PROM, however it doesn't display the correct output, which should be: "Hello BJ". Instead it shows random characters. https://pastebin.com/HbtaA04i
The way the PROM and the Decoder commands are as is follows:
An example of the PROM would be:
0011 0000 0001 0110 - Display the contents of registers 1 and 6. At the end of the operation, a 3716 will be sent to the display, and a “7” will be displayed (refer to an on-line ASCII table for doing display writes).