The Normal Try Statement is an Algol Statement which executes a sequence of statements until one is found which does not cause an exception.

The compiler  pushes a a Try Fault Marker on the Stack, and then a PCW to the next Else part of the statement. If a fault occurs in the Try part, the MCP traps the fault and branches to the next Else part.

The next Else part starts by deleting the PCW and replacing it with a new PCW to the following Else part, and then it branches to the start of the code for the current Else part.

This pattern is repeated through the Else parts. The final Else part is not protected, and should a fault occur, then normal fault handling is performed.

At the end of the Try Statement, the two Stack Cells for the Try Fault Marker and the PCW are deleted.

This cod was emitted by the Algol Compiler.

Try
  J:=A[I]
    0003:0001:0  LT48               BE
    0003:0002                       000000080001
    0003:0003:0  LT8   4            B204
    0003:0003:2  STAG               95B4
    0003:0003:4  MPCW               BF
    0003:0004:0       0003:0009:2   00040090A003
    0003:0005:0  VALC  (02,0002)    1002
    0003:0005:2  NAMC  (02,0004)    5004
Else
    0003:0005:4  NXLV               AD
    0003:0005:5  NTGR               87
    0003:0006:0  NAMC  (02,0003)    5003
    0003:0006:2  STOD               B8
    0003:0006:3  BRUN      000E:4   A2800E
Begin I:=1; J:=A[I];  End
    0003:0007:0  ONE                B1
    0003:0007:1  NAMC  (02,0002)    5002
    0003:0007:3  STOD               B8
    0003:0007:3  STON               B9
    0003:0007:4  NAMC  (02,0004)    5004
    0003:0008:0  NXLV               AD
    0003:0008:1  NTGR               87
    0003:0008:2  NAMC  (02,0003)    5003
    0003:0008:4  STOD               B8
Else
    0003:0008:5  BRUN      000E:4   A2800E
    0003:0009:2  DLET               B5
    0003:0009:3  MPCW               BF
    0003:000A:0       0003:000D:5   000A00D0A003
    0003:000B:0  BRUN      0007:0   A20007
Begin I:=0; J:=A[I];  End;
    0003:000B:3  ZERO               B0
    0003:000B:4  NAMC  (02,0002)    5002
    0003:000C:0  STOD               B8
    0003:000C:0  STON               B9
    0003:000C:1  NAMC  (02,0004)    5004
    0003:000C:3  NXLV               AD
    0003:000C:4  NTGR               87
    0003:000C:5  NAMC  (02,0003)    5003
    0003:000D:1  STOD               B8
    0003:000D:2  BRUN      000F:0   A2000F
    0003:000D:5  DLET               B5
    0003:000E:0  DLET               B5
    0003:000E:1  BRUN      000B:3   A2600B
    0003:0006:3  DBUN-LINK 0009:2   AA0038
    0003:000E:4  DLET               B5
    0003:000E:5  DLET               B5

The layout of the Try Fault Marker is defined in the MCP at 24606416,

Tag 4 - Fault Marker
Field	Name	Description
[19:3]	FaultMarkF	FaultTryMarkV = 4
[4:1]	TryInvalidF	If set, the Try word is invalid.
[3:1]	TryAllF	If set, this Try word protects from All faults
[2:3]	TryTypeF	The Type of Try Word, 1 = TryNormalV (Try Normal, GoTo PCW) 2 = TryExitV (Try Limited Error Procedure) 3 = TryReturnV (Try Limited Error Function Value)

This is the Stack dump from the Try statement,

***************BOUNDS ERROR      **************************************************    
 0022            7 6000B0 201D50  RCW:  ASD=00EA83, LL=2, Normal state 
 [User segment @ 0003:0005:4 (00106000)] 
 Segment Descriptor:  C 680000 001D50 ------ BLOCK#1
 Code:  3 000000 080001  3 B20495 B4BFFF  3 000400 90A003 
 >3 100250 04AD87< 3 5003B8 A2800E   
 0021 -----D[1]=>3 001200 090000 *ENVW: D[0] @ 0009 in the MCP     
 0020            1 0AC500 150000 *HISW: Previous HISW @ 0015 
 
 001F (02,0009)  9 800000 000042  FCW
 001E (02,0008)  0 000000 000002  Op:   Dec: 2 
 001D (02,0007)  7 600128 201D50  PCW:  ASD=00EA83, LL=2, Segment @ 0003:0009:2,
 Normal state 
 001C (02,0006)  4 000000 080001  TRY WORD, Normal Type
 001B (02,0005)  6 800000 000800  SCW: Blockexit marker: Single-dim Arrays   

See also the Limited Try Statement and the Try Expression.