Mnemonic Syntax
Notes:
Let's look at what the differences are between Mnemonic and Algebraic syntax, using five instructions as an example.
The mnemonic assembler might be called a traditional assembler. In the mnemonic syntax, to take the absolute value of the number that's in accumulator A and place the result in accumulator B, we use the ABS instruction and then over to the right we have the operands A and B.
In the second instruction, we are adding a number, 512, shifted to the left by three places using the shifter, and placing the result in accumulator A.
The third example shows how to move the stack pointer by 26 memory locations. We simply say frame 26. In C language, when we do a subroutine call we have to allocate space on the stack for the local variables. That space on the stack is considered to be a frame, so we say we want to have a frame of 26 words.
The fourth instruction, MAC, says multiply and accumulate the value pointed to by table one, multiply that value times the value in the T register (implied), and place the product in the B accumulator.
Finally, we pop the lower half of the accumulator off the stack and place it back in the accumulator. Now let’s see what the same instructions look like using algebraic syntax.