11 Transputer instruction set summary
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11.1.1
Product identity numbers
The loaddevice identity(lddevid) instruction (table 11.10)pushes thedevice typeidentityinto theAregis-
ter.Eachproductisallocatedauniquegroupofnumbersforusewiththelddevidinstruction.Productidenti-
ty numbers are given in table 11.3.
Product
IMS T425
IMS T805
IMS T225
IMS T400
Identity numbers
0 to 9 inclusive
10 to 19 inclusive
40 to 49 inclusive
50 to 59 inclusive
Table 11.3
Product identity numbers
11.1.2
Floating point unit
In the floating point unit (FPU) basic addition, subtraction, multiplication and division operations are per-
formedby singleinstructions.However,certain lessfrequentlyusedfloatingpointinstructionsareselected
by a value in registerA(when allocating registers, this shouldbe taken into account). A load constantin-
struction ldc is used to load register A the floating point entryinstruction fpentry then uses this value to
select the floating point operation. This pair of instructions is termed a selector sequence
In the Floating Point Operation Codes tables 11.23 to 11.29, a selector sequencecode is indicated in the
MemoryCodecolumnby
s
.ThecodegivenintheOperationCodecolumnistheindirectioncode,theoper-
and for the ldc instruction.
The FPUand processoroperateconcurrently, so theactualthroughput offloatingpoint instructionsis bet-
ter than that implied by simply adding up the instruction times. For full details see TransputerInstruction
Set – A Compiler Writer’s Guide
11.1.3
Notation
The Processor Cycles column refers to the number of periods
TPCLPCL
(refer to
ProcClockOut
) taken
by an instructionexecuting ininternal memory.The number of cycles is givenfor thebasic operationonly;
where the memory code for an instruction is two bytes, the time for theprefixfunction (one cycle) should
beadded.Someinstructiontimes vary.Where aletteris includedinthecyclescolumnitisinterpretedfrom
table 11.4.
Ident
b
m
Interpretation
Bit number of the highest bit set in register
A
. Bit 0 is the least significant bit.
Bit number of the highest bit set in the absolute value of register
A
. Bit 0 is the least signifi-
cant bit.
Number of places shifted.
Number of words in the message. Part words are counted as full words. If the message is not
word aligned the number of words is increased to include the part words at either end of the
message.
Number of words per row.
Number of rows.
does not apply to IMS T225
n
w
p
r
Table11.4
Instruction set interpretation