Section 5.5

Peripheral Incidents

Contents

5.5 

Introduction

5.5.1  

Paper Tape Devices

     .2  

Card Readers

     .3  

Card Punches and Line Printers

     .4  

Magnetic Tape Decks

     .5  

Drums

     .6  

Hough-Powell Device

     .7  

I.B.M. Tapes

     .8  

Electro-data units

     .9  

Ericsson Key Boards and Flexowriters C

     .10  

Orion 2/1900 Direct Data Link

 

 

5.5  Introduction

(see 5.3.21 and 5.3.25)

There are a number of events or incidents occurring on peripheral devices which cause an interruption and entry into OMP.

The possible events are described in this section.  Some are given code numbers for use with the 150/21 instruction (see 5.3.21) for specifying a restart should an event occur.

Default Action

If no restart has been specified and an incident occurs OMP carries out default action.  This is, in general to halt (suspend in the case of magnetic tape) - though in some cases the job is allowed to continue, to disengage the device (except for magnetic tape when it is left engaged unless the event is deck fail when it is disengaged) and to print a message (see 5.8.4) on the Flexowriter e.g.

jobname TRB HALTED PARITY FAIL

The default action for each device and incident is given in the appropriate sub-section.

Note that the programmer can control in some cases for slow devices whether the restart is entered with the device engaged or not and also can control whether the incident message is printed and also whether the link and information word are to be given - this is done by the setting of specific bits with the 150/21 instruction.  Magnetic tape restarts are entered with device engaged, except for deck fail.  If several incidents occur simultaneously then restarts (with links) are chained in Code number sequence; if one incident causes the device to be disengaged then it will be before any restart is entered.

Information Word

When specifying the restart, the programmer may indicate to OMP whether the link (into Y - 1) and the information word (into Y - 2) are to be given should the event occur (see 5.3.21).

The bit by bit information word describing the state of the state of the device may be obtained at any time by obeying a 140.13/142 instruction pair (see 3.14).  This bit by bit information is given here and in the appropriate subsection for each type of device.

Bits of the Information Word.

D9 to D23 (X-address field) for fast devices, (magnetic tape) gives the starting address of transfer.  For slow devices this is the current core-store address reached by the transfer when it failed, if possible.  On Orion 2 it will be close to the current address, for example for paper tape devices it may be the beginning of the current chunk.

D33 to D47 (Y-address field) give the finishing address of the transfer.  Bits D0 to D7 and D24 to D31 are used to give information about the type of failure and the state of various staticisors in the device.  Some of these bits will not cause programmerís action but they are, for the sake of completeness, given in the appropriate sub-section.  A bit is 1 if the event has occurred or the device is in that state.  Note that Orion 2 does not have address failure.

 

5.5.1  Paper Tape Devices

Code 1          PARITY FAIL
Wrong parity character on 7-track when read on a reader or when sent to a punch.  It is not possible to determine exactly which character has failed; restart procedure for a reader might involve operator action in pulling the tape back, for example.

Code 2          OPERATOR *
Tape low in punch.

Code 3          ADDRESS FAIL*
Address failure.  (Only Orion 1)

Code 4          DISABLED*
Device disabled.  The device is disengaged whether the programmer has asked for this or not.

Code 5          WRONG MODE
Wrong mode.  This is an attempt to use a 5-track mode on a 7-track device or vice versa.

Default Action

For events with Codes 1, 3, 4, 5 the default action is to halt the program, print a message (see 5.8.4.) and to disengage the device.

For event with Code 2 the default action is to print the message, to disengage the device and allow the program to continue.

Bits in the Information Word

D0 Wrong parity character.

D1 Attempt to use five-track mode on a seven-track device or vice versa.

D2 Device disabled.

D3 Device disengaged.

D4 Device set to read five-track tape.

D5 Address failure.  (Only Orion 1)

D6 Select (reader) or tape low (punch)

 

 

5.5.2          Card Readers

For other information which may be of use see 4.4.7.

Code 1          READ CHECK FAIL*
Failure of read check (Misread)

Code 2          ILLEGAL PUNCHING
Illegal punching in modes 1,2 or 4

Code 3          DISABLED*
Engineerís attention required because of card misfeed or wreck.  The reader is disengaged whether the programmer has asked for this or not.

Code 4          OPERATOR*
Operatorís attention required because hopper below 200 cards without weight in place or stacker full or reject pocket full etc.         

Code 5          ADDRESS FAIL*
Address failure.         

Default Action

For events with codes 1,2,3, and 5 the default action is to halt the program, to print a message and to disengage the device.

For event with Code 4 the action is to print a message, disengage the device and to allow the program to continue.  For hopper empty this default action may not be adequate; it may be advisable to have a Code 4 restart.

Bits in the Information Word

D0 address failure.  Only Orion 1.

D1 Operatorís attention - hopper low, stacker full etc.

D2 Engineerís attention - card misfeed, wreck

D3 Disengaged

D4 Illegal punching in modes 1, 2 or 4

D5 Switched to 65 columns

D6 Select button

D7 Failure of read check

D24 to D30 (Only Orion 1) are used to find where the failure of a read check occurred.  (4 columns are stored per word)

D24 1st column

D25 2nd column

D26 3rd column

D27 4th column

D28 Rows 5, 4, 10, 11

D29 Rows 7, 6, 1, 0

D30 Rows 8, 9, 2, 3

D31 Interstage.  On Orion 2 the interstage button must be pressed to read interstage.

 

5.5.3  Card Punches and Line Printers

For other information which may be of use see 4.5.7 and 4.5.8.

Code 1          OPERATOR*
Operator's attention required because of cards low or hopper empty or stacker full (Punch) or Paper low (Printer)

Code 2          BUFFER OVR
Buffer overflow (i.e.- more than 120 characters)

Code 3          BUFFER FAIL*
Checksum failure.  This indicates the contents of either the code or data buffer has been lost - it is not possible to determine which.  When this occurs OMP fills the code buffer with the standard code table whether a restart has been specified or not.  This failure may be overcome by repeating the transfer.         

Code 4          ADDRESS FAIL*
Address failure  (Orion 1 only)

Code 5          CARD WRECK*
Card wreck (Punch only)

Code 6          READ BACK FAIL*
Failure of read back check - at the read station.  (Punch only)

Code 7          DISABLED*
Device disabled.  The device is disengaged whether the programmer has asked for this or not.

Default Action

For event with Code 1 the action is to print a message (see 5.8.4) to disengage the device and to allow the program to continue.

For events with Codes 2 to 7 the action is to halt the program, to print a message and disengage the device.

Bits in the Information Word

D0 Failure of read back check.

D2 Device disabled

D3 Device disengaged

D4 Checksum failure (Orion 1 only)

D5 Address failure (Orion 1 only)

D6 Card wreck

D27 Operatorís attention - cards low, paper low, etc.

D31 Buffer overflow

 

 

5.5.4   Magnetic Tape Decks. (see 4.7.6)

Code 1     READ FAIL
Repeated read fail.

Code 2     WRITE FAIL
Repeated write fail.

Code 3     WRITE INHIBIT
Writing on isolated deck.

Code 4
Writing after reading backwards.  Note that a restart may be specified but it will never be entered as OMP does the necessary repositioning and the block is written.

Code 5     END OP TAPE
End of tape.

Code 6     LAST FAIL
Failure to write last block

Code 7     DECK FAIL.
Deck failure.  In this case the deck is disengaged.  When the deck becomes idle, on pressing the engage button OMP rewinds the tape and unloading is requested.  A restart for this can only relinquish the deck.

Code 8     FAIL
First fail.  If this restart has been specified OMP does not attempt the repeated read or write sequence but enters this restart without repositioning the tape - i.e. it "leaves you past the incorrect block".  If no restart has been specified code 1 or 2 action occurs.

Default Action

For events 1, 2, 3, 5 and 6 OMP suspends the program, prints a message and leaves the deck engaged.  For code 7, the difference is that the deck is disengaged.

Bits in the Information Word

D0     Orion 1 - this is Address failure
Orion 2 - this is parity failure when reading or writing from tape.

D1     Address discrepancy low (reading) or address discrepancy (writing).

D2     Writing on isolated deck or after reading backwards.

D3     Orion 1 - checksum failure in first adder (writing) or address discrepancy high (reading).
Orion 2 - Address high (reading)

D4     Orion 1 - checksum failure in second adder
Orion 2 - checksum failure.

D5     First sensing post - i.e. near end of tape.

D6     Deck interrupt - produced by various disabled conditions.

D7     Engage button.

D24  Writing.     On Orion 2 D24=0 and D25=1 when erasing

D25  Writing short gap mode.

D26,27 Values 0-3 for tape control being used.

D28  Tape moving forward in last transfer.

D29  Deck engaged - note that the significance of this bit is the reverse of D3 in other devices.

D30  Writing permitted

D31  Both sensing posts.

 

5.5.5   Drums

Some failures of the drum store are treated as failures of the central computer and cause all programs to be abandoned (see 5.8.4.1).  There  are no events which are programmers' option.

Bits in the Information Word

D0   parity failure in core store (on writing transfers), and current address parity failures.

D1   1 for writing.

D2   Drum address parity failure.

D3   Write parity failure.

D4   Read parity failure.

D6   Drum not at correct speed (Orion 2 only).

With a 141.13, 154 instruction pair (but not with a 141.13, 142 pair) a second word is obtained, which is written into X+1, containing the drum address.  This drum address is relative to the start of the drum control specified in the 141 instruction - thus bits 0-3 of the drum address are not obtained (since they are already known).  Bits 4-6 are always zero, bits 7-9 specify the drum, bits 10-16 the track and bits 17-23 the sector within the track.  The 17 bits obtained are written into X+1 as given below (the rest of X+1 is cleared)

Bit of
Drum
Address

Bit in store
(4096 word
  store)

Bit in store
(8192 word
  store)

Bit in store
(12288 or
16384 word
store)

Bit in store
(Store
>16384 words)

7

12

11

10

9

8

13

12

11

10

9

14

13

12

11

10

15

14

13

12

11

16

15

14

13

12

17

16

15

14

13

18

17

16

15

14

19

18

17

16

15

20

19

18

17

16

21

20

19

18

17

42

41

40

39

18

41

40

39

38

19

40

39

38

37

20

39

38

37

36

21

38

37

36

35

22

37

36

35

34

23

36

35

34

33

For Orion 2, the drum address is given in unscrambled form at the l.s. end of the word.

 

5.5.6  Hough-Powell Device

Code 1

A11 events

Bits in the Information Word

D0     Parity failure between DDC and Orion

D1     End of frame

D2     Buffer overflow

B3     Disabled

D4     Last transfer outward

D5     Current address parity failure

D6     Accept (select)

D7     Enable

 

 

5.5.7   I.B.M. Tapes

Code 1

All events

Bits in the Information Word

D0       Parity failure (addresses or in core store)

D1       Noise fault

D2       Reading forwards after writing or writing on isolated deck

D3       Zero character (writing BCD) or File mark (reading)

D4       Tape parity failure

D5       Load point (i.e. beginning of tape)

D6       Immediate interrupt

D7       Accept button

D24,25 - 00 for reading, 01 for erasing, 10 for write binary, 11 for write BCD

D26,27 - Control

D28     - 1 for last transfer writing

D29     - 1 for ready (engaged)

D30     - 1 for high density

D31     - End of tape.

 

 

5.5.8   Electro-data Units

Code 1

All events

Bits in the Information Word

D0     Wrong parity character read from the tape.

D1     Wrong Mode (e.g. mode 2 on *EAn).

D2     There is a switch on the deck called auto rewind.  If this is set then if the end of tape is reached the tape is automatically rewound and there is a peripheral incident with D2=1.  If the deck is interrogated while rewinding D2 will also be 1.

D3     1 for device disengaged.

D4     Always 1 on *EAn, always 0 on others.

D5     Address failure (address in core store not on tape).

D6     This event occurs if address information is found while reading data (i.e. *EAn).  This event will always produce D0 as well as D6.  It can be a hardware fault but it can also be a program error due (for example) to giving two read data transfers without an intermediate read address transfer.

 

 

5.5.9  Ericsson Key Boards and Flexowriters Type C

For the purpose of section 5.5 Ericsson Key Boards and Flexowriters type C are considered as seven track paper tape readers and seven track paper tape punches respectively.  (See 5.5.1 for detailed information).

 

5.5.10 Orion 2/1900 Direct Data Link

Code 1

Wrong parity character received from 1900 or in character received back from 1900 or in word from Orion C.P.U. to direct data link control - PARITY FAIL

Code 2

Transfer terminated  by 1900 with Orion set to send more words (output only) - SHORT TRANSFER

Default Action

The default action is to halt the program and print a message (see 5.8.4)
 

Bits in the Information Word

D0       Wrong parity character

D1       1900 termination type 1 (see note below) (output only)

D2       1900 termination type 2 (see note below) (output only)

D3       Device disengaged

D6       Select (input) or word parity (output)

Note:

     D1 and not D2 set
or D2 and not D1 set

The word given by "Current Address minus 1" has not been transferred to 1900.

     D1 and D2 set

The words given by "Current Address minus 1" and "Current Address minus 2" have not been transferred to 1900