Types of Operand • Addresses • Numbers —Integer/floating point • Characters —ASCII etc. • Logical Data —Bits or flags • (Aside: Is there any difference between numbers and characters? Ask a C programmer!)

We present a detailed look at different instruction formats, operand types, and memory access methods. We will see the interrelation between machine organization and instruction formats. This leads to a deeper understanding of computer architecture in general. Number of bits per instruction. Stack-based or register-based.

•Source operand reference –To this: (address of) argument of op, e.g. register, memory location •Result operand reference –Put the result here (as above) •Next instruction reference (often implicit) –When you have done that, do this: BR

Source operand reference • The operation may involve one or more source operands, that is, operands that are inputs for the operation Result operand reference • The operation may produce a result Next instruction reference • This tells the processor where to fetch the next instruction after the execution of this instruction is complete

Example –0 operands (1) • Syntax <operation> • Meaning (all arithmetic operations make reference to pre-defined registers, e.g. the accumulator and the top of the stack) <ACCUMULATOR><operation><TOP(STACK)> →→→<ACCUMULATOR> • Requires instructions (with an operand) to move values in and out the …

Ex: x87 load and store instructions perform conversions from any numeric format to IEEE and vice versa. Branch with Link (BL) can be used for function calls. Note that there is no divide instruction!

example, in LOAD A instruction, the operand specified in the instruction is a source operand whereas the operand specified in the STORE B instruction is a destination operand. Similarly, in one address instruction the implied operand (accumulator) can be either source

Study with Quizlet and memorize flashcards containing terms like Operation code, Source operand reference, Result operand reference and more.

Source operand reference •The operation may involve one or more source operands, that is, operands that are inputs for the operation Result operand reference •The operation may produce a result Next instruction reference •This tells the processor where to fetch the next instruction after the execution of this instruction is complete

There are four essential elements of an instruction; the type of operation to be performed, the place to find the source operand(s), the place to store the result(s) and the source of the next instruction to be executed by the processor.