Two on-line printers are available for attachment to the 1130 system. A system may include an IBM 1132 Printer Model 1 or Model 2 and/or an IBM 1403 Printer Model 6 or Model 7. The 1403 attachment also requires the attachment of the IBM 1133 Multiplex Control Enclosure.

IBM 1132 Printer

The 1132 Printer Model 1 (Figure 50) provides printed output for the 1130 system at maximum rates of 80 lines per minute (lpm) for alphameric printing and 110 lpm for all-numerical printing. The 1132 Printer Model 2 provides maximum printing rates of 40 lpm for aiphameric printing and 55 lpm for all-numerical printing. The print line is 120 print positions long; horizontal spacing is ten characters per inch. Vertical spacing, which is preselected by the operator, is six or eight lines per inch.

Figure 50. IBM 1132 Printer
Figure 50. IBM 1132 Printer

Functional Description

Both models of the 1132 contain 120 printwheels, one for each print position. Each printwheel contains a 48-character alphabet consisting of 26 alphabetic characters, 10 numeric characters, and 12 special characters. Special (FORTRAN) characters are as follows:

    &  -  /  .  $  ,  *  (  )  '  +  =

All printwheels rotate continuously and in synchronization with each other. Each wheel moves forward to print when the data in the output record specifies that the character to be printed is in position. Thus, all similar characters for the entire line are printed on the same cycle. Forty-eight cycles (one for each character possible) are required to print a complete line.

The 1132 uses interrupt circuitry and responds on level 1.

Forms Control

Forms control is provided through a tape-controlled carriage that uses the standard IBM carriage tape. Channels 1 through 6,9, and 12 are available to the stored program.

Spacing is always performed one line at a time under control of the stored program in the CPU.

Carriage skipping is initiated by the stored program and stopped by the program when the predetermined line is reached. Skipping speed is 10 inches per second.

Note: A skip operation must not be less than four lines.

Data Format

The 1132 character code is shown in the appendix. Each character occupies the first eight bits of a core storage word. The data to be printed is assembled in core storage in the same order, including spaces, as the line that is to be printed. During each of the 48 cycles necessary to print all 48 characters, the character next in position to print is read from the character emitter and is compared with each character of the output record, all by the CPU program. For each equal comparison, the program places a 1-bit in the printer scan field in the position corresponding to the printwheel to be fired. The printer scans the field in a cycle-steal mode and fires each printwheel whose position contains a 1-bit. The printer scan field is located in core storage locations 32 through 39. The 16 bits of each of the first seven words and bits 0 through 7 of the eighth word represent the 120 printwheels.


The IBM 1132 Printer operates under direct program control of the CPU.

Printer I/O Control Commands

The 1132 is addressed by the binary device code of 00110.

Read Emitter (010)

Read Emitter IOCC

This command causes the eight-bit EBCDIC code of the next character emitted by the printer to be read into bits 0-7 of the core storage location specified. Bits 8-15 are reset to zero.

Control (100)

Printer Control IOCC

This command causes the execution of the function specified by the modifier bit. A 1-bit in the position indicated in parentheses after each command causes the operation described.

Start Printer (Bit 8): This causes the printer to start taking the printer scan field information. The printer continues to take print scan cycles as required until it receives a stop printer command. Each position that contains a 1-bit causes the corresponding printwheel to print the character in position on that cycle. After the field of eight words has been scanned, a 1-bit is placed in bit position 0 of the 1132 device status word. (See Figure 51) This causes an interrupt when level I is the highest level waiting.

Stop Printer (Bit 9): This instruction causes the printer to be put in a ready (not busy) state and inhibits subsequent printer interrupts. The stop printer instruction should not be given until all of the following conditions are met:

Start Carriage (Bit 13): This command initiates a skip operation, which is halted by a stop carriage instruction.

Stop Carriage (Bit 14): This command stops the carriage at the end of a skip operation. A punch in carriage control tape channel 1, 2, 3, 4, 5, 6, 9, or 12 initiates an interrupt request, identified by bit 1 of the DSW. When the desired tape channel bit in the DSW is on, a stop carriage command should be given.

Space (Bit 15): This command is given to space the carriage one line. After the space operation, an interrupt is initiated and a 1-bit is put in bit position 2 of the DSW to indicate spacing is completed. Another space can now be initiated.

Sense Device (111)

Printer Sense Device IOCC

This instruction causes the DSW of the 1132 Printer to be placed in the ACC. The functions of the bit positions of the DSW are shown in Figure 51.

If bit 15 contains a 1, the interrupt responses in the DSW are reset.

DSW Indicators

Three interrupts are associated with the 1132, each on level 1. The associated indicators are turned on in the DSW.

Read Emitter Response (Interrupt): After a start printer command has been executed, the 1132 will interrupt the CPU program each time the printwheels are aligned to print another character. The read emitter command must then be executed to determine the character to be printed.

Figure 51. 1132 Device Status Word
Figure 51. 1132 Device Status Word

Skip Response (Interrupt): This indicates an interrupt which is initiated by the 1132 each time the carriage brushes detect a punch in the carriage tape while a skip operation is in progress. The CPU program must test the DSW bits to determine if the carriage is at the proper channel.

Space Response (Interrupt): This indicates an interrupt which turns on at the completion of a space operation to signal the CPU program.

Note: After an interrupt has been serviced, the level must be reset by a BOSC instruction.

Carriage Busy: This indicator turns on when the 1132 begins carriage movement. It turns off when movement stops.

Print Scan Check: This indicator is turned on when the printer attachment addresses word 39 and there is not a 1-bit in position 15. A 0 in bit 15 indicates that the printer subroutine did not finish setting up the print scan field.

Not Ready: This indicator is turned on by an out-of-forms condition, motor power off, or at the end of the operation in progress if the stop key is pressed.

Printer Busy: This indicator is turned on when an XIO start printer instruction is executed for the 1132. It is turned off by an XIO stop printer instruction to the 1132, by a system reset, or by a CPU stop.

Carriage Control Channels: As each hole in the carriage tape is read after a start carriage control command, the associated indicator in the DSW is turned on.

Programming Notes

The status of the 1132 indicators should be checked before a line is printed. This is accomplished by transferring the printer DSW into the ACC with a sense device command. The modifier bit (bit 15) of the sense device command should be set to 0 to prevent reset of the DSW responses and indicators. Bits 3, 5, and 6 of the DSW are tested and if all three positions are 0, the printer is ready to print the next line. A start printer control command is then given to start the sequence. A scan field transfer, using cycle steal cycles, takes place under control of the printer. Therefore, the scan field must be clear and have a 1-bit in position 15 of core storage word 39 before the start print command is given.

After the code of the next character has been emitted by the printer, a level 1 interrupt is given and the character is read into core storage by a read emitter command. There are 11.2 ms available to test each position of the output record with the character read and set up the 1 bits in the printer scan field. At the end of the 11.2 ms, the 1132 attachment begins its scan and fires each printwheel with a corresponding 1-bit in the printer scan field. If the program has been interrupted for a considerable period by higher levels, the scan may not have been completed. To insure that the program detects this condition, the first steps of the printer subroutine for each character should clear the printer scan field to 0's and, upon completion of the programmed scan, place a 1 bit in position 15 of the eighth word (39). When the printer attachment scans the field it checks this position. If it is 0, the print scan check indicator (bit 4 of the DSW) is turned on. The program can test this indicator and branch to an error routine that provides 47 idle scan cycles and resumes programmed scanning at the point where the scanning was interrupted. This results in overprinting of the characters that were printed unless the error routine keeps track of the positions that were printed and does not set them up again on this scan.

After the final scan cycle for a line of printing, 16 idle scan cycles must be taken before spacing or skipping is started to allow time for completion of the mechanical operation of printing the last character. If the operation is a single or double space, the next scan cycle can be started two scan cycles after the last space command is given.

During an idle scan cycle the printer scan field should be set to 0's, except for bit 15 of the eighth word (39), to prevent the print scan check indicator from being turned on.

1132 Usage Meter

This meter starts when both of the following conditions are present:

  1. The unit is selected for operation by program control.
  2. The 1131 usage meter is running.

The 1132 meter continues to run simultaneously with the 1131 meter unless a manual space or manual carriage restore is initiated by the operator.

IBM 1403 Printer

The IBM 1403 Printer (Figure 52) greatly increases the output capabilities of the IBM 1130 Computing System while reducing the time that the CPU is required to print, thus leaving more time for other functions. The 1403 is available in two models for attachment to the 1130:

  1. The model 6 has a maximum printing speed of 340 (or 210) lines per minute (lpm), depending upon the attachment feature specified in the 1133 Multiplex Control Enclosure.
  2. The model 7 has a maximum printing speed of 600 lpm.

Each printer can print 48 different characters in 120 positions. There are 26 alphabetic, 10 numeric, and 12 special characters.

Vertical spacing and skipping are initiated by the stored program. Horizontal spacing is ten characters per inch. Standard vertical spacing is six and eight lines per inch, controlled manually by the operator. Skipping is about 33 inches per second.

Figure 52. IBM 1403 Printer
Figure 52. IBM 1403 Printer



The alphabetic, numeric, and special characters are assembled in a chain. As the chain travels in a horizontal plane, each character is printed as it is positioned opposite a magnet-driven hammer that presses the form against the chain.

Data to be printed must first be edited, translated to the 1403 binary code (see Appendix), and arranged in core storage in exactly the form that it is to be printed. The data format in core storage is two seven-bit characters per word (Figure 53).

Figure 53. 1403 Data Format Hexadecimal Bits
Figure 53. 1403 Data Format Hexadecimal Bits

Spacing and Skipping

Spacing is always performed one line at a time under control of the stored program in the CPU.

Carriage skipping is controlled by prepunched holes in a paper or plastic tape that corresponds in length to the length of one or more forms. Holes punched in the tape stop the form when it reaches any predetermined position.

Note: A skip operation must not be less than two lines.

Control Tape

The control tape has 12 columns, indicated by vertical lines. These positions are called channels. Holes can be punched in each channel throughout the length of the tape. A maximum of 132 lines can be used to control forms although, for convenience, the tape blanks are slightly longer. Horizontal lines are spaced six to the inch for the entire length of tape. Round holes in the center of the tape are prepunched for the pin-feed drive that advances the tape in synchronization with the movement of a printed form through the carriage. The effect is exactly the same as though the control holes were punched along the edge of each form.


All operations of the 1403 are under control of the stored program in the CPU.

Data to be printed must be edited, translated to the 1403 binary code, and arranged in core storage in exactly the form that it is to be printed. The 1403 has a fixed length data field of 120 characters or 60 words.

Initiate Write (101)

Initiate Write (101)

An initiate write command transfers data from core storage to the print buffer using the cycle steal method.

During data transfer each core location to be printed is addressed twice. During the first cycle, bits 1-7 are transferred to an even address of the print buffer. During the second cycle, bits 9-15 are transferred to the next higher odd address of the print buffer.

The total time demand on the processor is dependent on the core storage cycle time. Approximately 432 us. is required for the 3.6-us. core storage, and approximately 264 us. is required for the 2.2-us. core storage.

The printer does not interrupt the CPU until after the 120-position buffer is filled. It then initiates a transfer complete interrupt on level 4.

After completion of printing the line a level 4 interrupt is initiated to signal print complete.

Control (100)

1403 Printer IOCC Control function

An XIO control command initiates a single line space.

Write (001)

1403 Printer IOCC Write function

An XIO write command controls carriage skipping. This command causes the carriage to skip even if it is at the specified channel. It skips until that channel is detected again. The carriage may be controlled to skip to any channel 1-12 by placing a 1-bit in positions 4-15 of the core location specified by the address.

The carriage will stop only on an exact compare of all corresponding bits. Therefore, if more than one channel is punched on a line, the corresponding bits must be set in bits 4-15 of the address word for the carriage to stop on that line, likewise, if no bit is present in bits 4-15, the carriage will stop on the next line that has no channel punches.

A carriage control command given prior to loading of the print buffer causes immediate execution of the command. If the command is given during loading of the buffer, the command is not executed until after the line is printed. The programmer must check to insure that the carriage is not busy when the command is given.

Figure 54. Sense Device (1403)
Figure 54. Sense Device (1403)

An XIO sense device command (Figure 54) causes the 1403 DSW (Figure 55) to be placed into the accumulator. If bit 15 is on when the command is executed, the DSW interrupt indicators and channel 9 and 12 indicators are reset.

DSW Indicators

Transfer Complete Interrupt: The 1403 requests this interrupt when the 1403 buffer is full.

Print Complete Interrupt: This interrupt indicates the 1403 has completed printing a line.

Carriage Interrupt: This interrupt indicates the 1403 has completed a skip or space operation.

In addition to the preceding interrupts, the following status conditions are also indicated in the 1403 DSW.

Parity Check: This indicates an even bit count of the seven bit print buffer data word.

Print Check: This indicates an error occurred in modification of the buffer address register.

Sync Check: This indicates that the print chain is not synchronized with the compare counter.

Figure 55. 1403 Device Status Word
Figure 55. 1403 Device Status Word

Carriage Channel 9: This indicates the carriage passed a channel 9 punch in control tape.

Carriage Channel 12: This indicates the carriage passed a channel 12 punch (normally used for the last printing line on a form) in the control tape.

Carriage Busy: This indicates that the carriage is performing a space or skip operation. This bit goes off when bit 3 comes on to signify completion.

Printer Busy: This indicates that the 1403 buffer is being loaded or a line is being printed.

Not Ready: This indicates the 1403 is not ready. Printing, spacing, or skipping under program control cannot occur until the 1403 is ready.

1403 Usage Meter

This meter will run when the following conditions are present:

  1. The 1133 is in an enable status.
  2. The 1403 is selected for operation by program control.
  3. The 1131 usage meter is running.

This meter will run simultaneously with the 1131 meter until either stopped by the operator or the 1133 is placed in a disable status.

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