Dale - Computer Science Illuminated 225

Dale - Computer Science Illuminated 225 - 26788.2 on the...

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198 Chapter 7 Low-Level Programming Languages Because direct addressing is used, this instruction writes out the ASCII character stored in the location named in the operand specifier, location 000A. What is written? We can’t say unless we know the contents of byte 000A. The ASCII character corresponding to whatever is stored at that location is printed. 7.4 A Program Example Let’s look at an example using machine language. Programs are written to solve problems, so we first begin with the problem and the algorithm to solve it. Problem and Algorithm Let’s start with a very simple problem; let’s write
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Unformatted text preview: 26788.2 on the screen. The algorithm is easy. Is this a concrete step? It certainly would be if we were going to implement it in a high-level programming language. However, it is not a concrete step in machine language. Let’s further specify it by writing each letter separately. Write “Hello” Write “H” Write “e” Write “l” Write “l” Write “o” Write “Hello” Instruction specifier Operand specifier 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 1...
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