Appendix 611
complex = data-type(components: real, imaginary; usually floating complex)
field : data-type(carrier: word: components: i-unit-list: format: á element-rangeñ )
COMMENT
A field is a subset of bits, or characters, or bytes in a word. It is usually, though not always, an interval. See ISP.2 for element range.EXAMPLES
|
12, 101, 5; +125, -126; |
unsigned; and signed integers |
|
+72 , -999; |
sign-magnitude |
|
1012, 778, A916; |
binary, octal and hexidecimal |
|
+ 6.257; 6.257 X 100; |
mixed, and floating point |
|
(1, 2, 2.7); |
complex |
|
1F 2; 7F 8 |
digit set specification: stands for 102÷ 112 ; and 708÷ 718÷ . . . ÷ 778 respectively |
|
? |
questionable value |
2. Instruction
2.1 instruction : = data-type(referent: instruction-expression; operation-code: field; operand-list; operand: data-type)
instruction-expression : = condition ® action-sequence
action-sequence : = (step÷ next step)-list
step : = action÷ condition ® action-sequence
action : = memory-expression ¬ data-expression
memory-expression : = (
memory *[address-range]-list *á element-rangeñ character-base ÷
memory-expressionð memory-expression ÷ memory-expression-list)
address-range : = address ÷ address: address÷ address-expression÷ address-range-list
address-expression : = operation-expression(address-operations)
element-range : = field ÷ field-list
character-base : = + integer base i-unit
condition : = boolean ÷ memory-expression
data-expression : = data-type ÷ memory-expression÷ operation-expression÷ data-expression{data-type}
operation-expression : = (nonary-operation ÷
unary-operation data-expression÷
data-expression binary-operation data-expression÷
data-expression n-ary operation data-expression . . . ÷
function(data-expression-list) / f(data-expression-list)÷
operation-expression *{ operation-modifier}
operation-modifier : = data-type ÷ name See GC 10
2.2 The instruction is a data-type and thus has both a representation in memory and a referent, which is called the instruction-expression. The only fixed part of the instruction format is the operation-code. All the rest are operands to be used by the instruction-expression.
2.3 The instruction-expression, when interpreted, takes the processor through a sequence of steps which result (possibly) in some change of state of the computer system that holds past the period of interpretation, thus constituting a new initial condition for the next instruction. The action sequence has two structural features. First, steps (and subsequences of steps) may be conditional on a boolean value, developed according to a condition. Second, steps may be accomplished in parallel or in series. Any set of steps between two occurrences of the term "next," are to have all their data expressions developed prior to any transmission of data. Thus, all their data is a function of the existing state at the start of the sequence. At the occurrence of the term "next," all pending transmissions are made, so that the state for the following sequence of steps is now different (if there were in fact transmissions to be made).
2.4 All permanent changes in state are accomplished by means of actions, which take data developed according to a data expression and transmit it for storage in a memory, as designated by a memory expression.