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 |
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 programmer’s 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.
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)
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*
Engineer’s attention required because of card misfeed or wreck. The reader is
disengaged whether the programmer has asked for this or not.
Code 4 OPERATOR*
Operator’s 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 Operator’s attention - hopper low, stacker full etc.
D2 Engineer’s 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.
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 Operator’s attention - cards low, paper low, etc.
D31 Buffer overflow
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.
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 |
Bit in store |
Bit in store |
Bit in store |
Bit in store |
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.
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
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.
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.
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).
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 |
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 |