7/31/2019 GPSS4

1/5

GPSS Module 4TEST Block

A TEST block compares values of SNAs and controls thedestination of the entering transaction based on the result of

comparison.

Format TEST O A,B,C

O: A relational operator. E, G, EG, L, LE, or NE.

A: The test value

B: The reference valueC: The destination value

If C operand is missing, then it works in a refuse mode.

That is, the entering transaction would not be allowed to

enter here if the test proves unsuccessful.

e.g. TEST G C1,1000

If the entering transaction finds the system clock value

greater than 1000, it would be allowed to proceed to the

next block. Otherwise, it would be blocked to enter here.

Blocking will continue until the condition changes.

TEST GE Q$CPU1Q,Q$CPU2Q,IO

When a transaction enters here, compute the current queue

lengths ofCPU1Q and CPU2Q. If the former is greater than

or equal to the latter, it proceeds to the next sequential

block. Otherwise, it goes to the block labeled IO.

7/31/2019 GPSS4

2/5

GATE Block

A GATE block works like a valve affecting the flow basedon the state of an entity.

Format: GATE 0 A,B

O: Conditional operator. FNV, FV, I, LS, LR, M, NI, NM

NU, SE, SF, SNE, SNF, SNV, SV, U

A: Entity name to be tested

B: Destination block if test fails.

The meaning of conditional operators.

FNV: The facility in operand A must be unavailable

FV: The facility in A must be available

I: The facility in A must be currently interrupted

LS: The logicswitch in A must be in a set state

LR: The logicswitch in A must be in a reset stateM: The match block specified by A must have a related transaction

waiting for a match condition.

NM: No transaction waiting under match condition.

NU: Facility in A is not in use

SE: Storage specified by A is empty

SF: Storage specified by A is full

SNE: Storage specified by A has at least one transaction

SNF: Storage specified by A has at least one available storage unit.SNV: Storage specified by A is unavailable

U: The facility specified by A is in use.

7/31/2019 GPSS4

3/5

e.g. GATE SNF HALL

Transaction is accepted in this block if the storage HALL is

not full. Otherwise, transaction stays where it is.

GATE LR DBLOCK,THERE

If the logic switch DBLOCK is reset (open lock), accept the

transaction here. Otherwise, it goes to the block marked

THERE.

GATE blocks are extremely powerful, and they can chewup a lot of CPU time in unsuccessful tests. Design your

code to reduce frequency of unwanted unsuccessful tests.

The output from the simulation run

7/31/2019 GPSS4

4/5

As we can gather, LOGIC Block changes the status of a

logicswitch entity.

Format LOGIC O A

O: Logical operator S, RS

A: Logical switch

An example. Simulation of a traffic junction. East-West &

North-South traffics hinged on an intersection they bothshare. First part is the traffic-light system, the second and

the third part are the two traffic corridors.

7/31/2019 GPSS4

5/5

The report looks like