-E EOD 50000B 00650000
F EOD 50100B 00650100
G EOD 50000B,2 20650000
H EOD 50100B,2 20650100
DISW DISCONNECT CHANNEL W
The channel is disconnected. Its unit address register is un-conditionally set to 00 regardless of whether a device is cur-rently being addressed by the channel. Any device which is connected to the channel is disconnected from the channel.
The EOM/EOD instructions (and their octal configurations) that are used to disconnect the various channels are:
Channel W Y C D E F G H
EOM/EOD EOM 0 EOM 100B EOM 0,2 EOM 100B,2 EOD 0 EOD 100B EOD 0,2 EOD 100B,2
Configuration 00200000 00200100 20200000 20200100 00600000 00600100 20600000 20600100 ASCW ALERT TO STORE ADDRESS FROM CHANNEL W
The channel is alerted for a PIN instruction to follow. This instruction does not affect the operation of the channel. See
"Direct Parallel Instructions" for a detailed discussion of PIN.
This configuration of EOM/EOD is always used in conjunc-tion with PIN to determine the current compleconjunc-tion status of an I/o operation being performed by the selected channel.
The two instructions should be written in the order EOM/
EOD, PIN. When these two instructions have been exe-cuted, the contents of the effective location of the PIN in-struction contains the following information:
Contents of the channel MAR
o
7 23The EOM/EOD instructions (and their octal configurations) that are used to alert the various channels to store the con-tents of their memory address registers are:
Channel EOM/EOD Configuration
W EOM 12000B 002 12000
Y EOM 12100B 00212100
C EOM 12000B, 2 202 12000
D EOM 12100B, 2 202 12100
E EOD 12oo0B 006 12000
F EOD 12100B 006 12100
G EO D 12000B, 2 206 12000
H EOD 12100B,2 206 12100
TOPW TERMINATE OUTPUT ON CHANNEL W
This instruction is used to terminate channel output when the last word of a block has been delivered to the channel.
38 Compatible/Extended Input/Output Modes
After the last character in the channel buffer is delivered to the peripheral device, the channel is disconnected.
This instruction is always used to terminate a non interlaced channel W output operation. It may be used with all com-munication channels if the particular function selected is terminal function II (IOSP) but no further data output is re-quired (see "Extended Mode Terminal Functions"). The EOM/EOD instructions (and their octal configurations) that are used to terminate output on the various channels are:
Channel EOM/EOD Confi§1uration
W EOM 14000B 002 14000
Y EOM 14100B 002 14100
C EOM 14OooB,2 20214000
D EOM 14100B,2 202 14100
E EOD 14000B 006 14000
F EOD 14100B 006 14100
G EOD 14000B,2 206 14000
H EOD 141ooB,2 206 14100
COMPATIBLE/EXTENDED INPUT/OUTPUT MODES
The termination of an I/O operation and the interrupts that may be associated with that term ination fall into two classes:
compatible and extended. The choice of one of these two modes of input/output operation determines how the system behaves when the termination of on I/O operation occurs.
As mentioned in Section 2, "Interrupt System", interrupts occurring at a single level (e. g., location 31 B, etc •. ) can have different names (e. g., zero word count and end of word). These names reflect the different I/O mode in op-eration when the interrupt occurs. The differences include the timing of interrupt occurrence relative to the I/o op-eration and type of interrupt requested.
The compatible mode of operation for channels W, Y, C, and D is directly compatible with the SDS 910/920 mode of I/O (interlaced) operation. The type of interrupts that can be requested are the end-of-word and end-of-transmission interrupts.
The extended mode for all channels expands the I/O capa-bilities to include the terminal and arming functions dis-cussed below. The types of interrupts that can be requested are the zero-word-count and end-of-record interrupts.
COMPATIBLE MODE TERMINAL FUNCTIONS The following description and diagram illustrate the auto-matic terminal functions of a time-multiplexed communica-tion channel when operating in the compatible interlace mode of data transmission.
Input C Words
If C words are received before the end-of-record detected, the interlace is disengaged and the end-of-word (EOW)
interrupt signal is generated when the next word fi lis the word assembly register. Since the channel continues to ac-cept characters, a character rate error occurs if the record is longer than C+1 words (unless the peripheral device is dis-connected from the channel or the remainder of the record is otherwise disposed of). At the end-of-record, the peripher-al device is disconnected, the channel becomes inactive, and the channel generates an end-of-transmission (EOT) in-terrupt regardless of whether or not C words have been read.
Output C Words
When C words are transmitted, the channe I is disconnected and the EOT interrupt is generated when the last character is output.
Input or output characters
:"I-_-I~ C I ear UAR and send
in ut Di sengage inter! oce, Send EOW interrupt when next word is assembled in buffer
EOT interrupt
Terminate output, c I ear UAR, and send EOT interru t
EXTENDED MODE TERMINAL FUNCTIONS
A 2-bit function code in bit positions 15 and 16 of the input/
output control mode EOMjEOD (executed after the alert channel EOMjEOD) controls the termination of input/output operations in the extended mode as follows:
15 16 Terminal Function
o
0o
1 1 0 1 1input/output of a record and disconnect (lORD) input/output unti I signal then disconnect (IOSD) input/output of a record and proceed (IORP) input/output unti I signal then proceed (IOSP) These functions are described below with the letter C rep-resenting the specified word count of the transmission. Fol-lowing each of the discussions is a diagram representing the automatic terminal actions of the channel while under
control of the specified terminal function in the extended interlace mode of data transmission.
The following table summarizes the term inal functions that should be used with various devices. The IOSP can always be used with any device; however, it causes a disconnect only when an end-of-record signal is received by the chan-nel from a peripheral device during input.
Device Typewriter Paper Tape
Cards
Printer Magnetic Tape
Input IOSD
lORD, IOSD (IORP can be used but there is no advantage to doing so)
lORD, IOSD (this should not normally be used to discon-nect in the middle of a half-read card)
lORD, IORP
Input/Output of a Record and Disconnect
Output IOSD IOSD
IOSD, lORD
IOSD, lORD lORD, IORP
Clear Ut>.R and send .---... E OR interrupt
Terminate output or ignore remai nder of input record
A program should not use the lORD function with devices that do not have end-of-record conditions on output (e. g., devices such as the paper tape punch and typewriter). These devices do terminate output but give the program no indication when
they receive the last characters.
Extended Mode Terminal Functions 39
Input C Words. If C words are received before the end-of-record is detected, the rest of the end-of-record is ignored. At the end-of-record, the peripheral device is disconnected and the channel becomes inactive.
Output C Words. When C words are transmitted, the device is signaled that the last characters have been transmitted.
When the peripheral device has generated the end-of-record and, if necessary, checked the val idity of the record, it sends an end-of-record response to the channel, which causes the channel to disconnect and an end-of-record in-terrupt (if armed).
The line printer generates the end-of-record response when it completes the printing of a line. If the printer encounters any print error or faults, it sends a signal to the channel that sets the channel error indicator; this can occur since the printer has not disconnected from the channel. The lORD function is useful when the program is to print several I ines and the program is not otherwise to use the channel between I ines. When the printer completes each I ine, it causes an end-of-record interrupt (assumed to be armed), notifying the program that it can immediately transmit the next paper control instruction and the next I ine image.
The unbuffered card punch operates similarly. It generates the end-of-record response after punching each row. Ifany faults occur during the punching of the entire card, the card punch sends a signal to the channel that sets the channel er-ror indicator; this occurs after punching the last row (row 9}.
Input/Output until Signal then Disconnect
Input or output characters
1----.-.... Clear UAR and send EOR interrupt
The IOSD function is designed for use on devices that are normally operated on the basis of the word count only.
Typewriters and paper-tape devices are of this type, as are the printer and card punch when the user does not wish to stay connected until the operation is complete.
40 Extended Mode Terminal Functions
Input C Words. When C words are received, or when the end-of-record is encountered, the device is disconnected and the channel becomes inactive. If the channel discon-nects because of zero word count, an end-of-record inter-rupt (if armed) will be generated in addition to the zero word count interrupt; if both are armed, the zero word count interrupt wi II occur first.
Output C Words. When C words are transmitted, the chan-nel disconnects the device and becomes inactive when the last character has been transmitted. If an end-of-record signal is received before the count reaches zero, the chan-nel will disconnect immediately.
Input/Output of a Record and Proceed
Input or output characters
Send EOR interrupt.
If magnetic tape, tape gap signal is
"'y-e-s---'" true for 1 ms. If no
Send ZWC interrupt
Terminate output or ignore remainder of in ut record
new EOM/EOD in this time, clear UAR.
A program should not use the IORP function with devices that do not generate end-of-record responses upon output termination; such devices are paper tape and typewriter.
These devices do terminate output but give the program no indication when they receive the last character.
The IORP should also not be used with the printer and card punch since these devices expect the channel to disconnect after they send an end-of-record signal to the channel.
Input C Words. If the channel receives C words before the peripheral device encounters the end-of-record, the chan-nel ignores the rest of the record (to the end-of-record).
When the peripheral device sends the end-of-record signal to the channel, the channel sets its end-of-record indicator;
this signal sets the end-of-record interrupt (if armed). The channel does not disconnect. The channel is now in an
"interrecord" condition.
When the peripheral is magnetic tape, the tape continues to move when the tape handler encounters the end-of-record.
The end-of-record occurs when the tape read-heads en-counter tape gap; this also causes a tape signal to "come high". If the program executes a new read-tape or scan-tape. EOM/EOD during the intra-gap time (approximately one mi II isecond, while the tape gap signal is high), the tape remains in motion and proceeds to read or scan the next record. If the program executes no such EOM/EOD before the tape gap signal drops, the channel disconnects and the tape comes to a stop. No additional interrupt occurs. This is the only condition that causes a channel to disconnect automatically.
All other input devices remc;in connected unti I the program takes further action. The paper tape reader remains in mo-tion; the program should issue a disconnect channel EOM/
EOD if the program is not reading any more tape. To pro-ceed after the end-of-record occurs, the program first re-loads the interlace portion of the channel and then executes a buffer control mode EOM/EOD to reinitialize the channel.
Otherwise, the channel immediately term inates any attempt to use its interlace portion since the channel is aware that it is still active and in the end-of-record condition. When the program continues from an interrecord condition, the program should use an extended-mode terminal function.
An IORP function should not be used to read from or write with devices that do not have end-of-record signals (e. g., the typewriter and paper tape punch).
Output (Words. When the channel transmits (words, it sends a signal to the connected peripheral device indicating that the devi ce has the last word. When the peripheral de-vice receives and checks the validity of this last word, it sends an end-of-record response to the channel, which causes the channel to generate an end-of-record interrupt (if armed) and set the interrecord indicator; the channel does not disconnect.
When the peripheral device is magnetic tape, the tape con-tinues to move after it signals end-of-record. As in reading tape, the signal causes the tape gap signal to come high.
If the program executes a new write-tape or erase-tape EOM/EOD during the intra-gap time (approximately one millisecond), the tape remains in motion and proceeds to write or erase a new record. If the program executes no such EOM/EOD before the tape gap signal drops, the chan-nel disconnects and the tape comes to a stop. No interrupt occurs at this time, This is the only condition that causes a channel to disconnect automatically.
To proceed after the end -of-record occurs, the program first reloads the interlace portion of the channel and then' executes a buffer control mode EOM/EOD to reinitial ize the channel UAR. Otherwise, the ~hannel immediately terminates any attempt to use its interlace portion, since the channel is aware that it is still active and in the end-of-record condition. When the program continues from an
interrecord condition, the program should use an extended-mode terminal function.
Input/Output until Signal then Proceed
Input or output characters
Send EOR interrupt.
If magnet i c tape, tape gap signal is J--+ttrue for 1 ms. If no
Data overrun if i nter-lace not rei oaded or TOP not given
new EOM/EOD in this time, clear UAR.
Input (Wards. If the channel receives ( words before the peripheral device encounters the end-of-record, the chan-nel generates a zero word count interrupt (if armed). The program should reload the interlace port ian of the channel to continue reading the record. Failure to reload the inter-lace before the peripheral device sends enough characters ta overfill the word assembly register causes a character rate error; this sets the channel error indicator.
When the peripheral device encounters the end -of-record, the IOSP function operates identically I ike the IORP function.
Output (Words. When the channel has transmitted ( words, it generates a zero word count interrupt (if armed); the chan-nel does not terminate output. The program should reload the interlace portion of the channel to continue writing in the same record. Fai lure to reload the interlace before the peripheral device requests the next character causes a char-acter rate error; this sets the channel error indicator.
If the program executes a terminate output EOM/EOD after the channel has counted (down to zero, the channel term inates the outputand operates as an IORPfunction from this point on.