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Unlimited Dot Pattern Generation for a Matrix Printer Requiring Extended Character Sets

IP.com Disclosure Number: IPCOM000077726D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 4 page(s) / 44K

Publishing Venue

IBM

Related People

Cotton, RF: AUTHOR [+2]

Abstract

Printer actuation signals for use with a matrix pattern printer are selected from different storage locations. A dot pattern wire matrix printer control is described by way of example, wherein specific data bytes to control the firing of printer wires are selected between a read-only store (ROS) and core storage. The ROS can contain data for alpha-numeric printing, while the printing of special characters such as Katakana is controlled by the retrieving of bytes from core storage. Operation is on a cycle-steal basis and the attachment includes the logic circuitry for inspecting each data byte retrieved in the program execution, to decide whether the ROS or core storage will be used for wire firing control signal generation.

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Unlimited Dot Pattern Generation for a Matrix Printer Requiring Extended Character Sets

Printer actuation signals for use with a matrix pattern printer are selected from different storage locations. A dot pattern wire matrix printer control is described by way of example, wherein specific data bytes to control the firing of printer wires are selected between a read-only store (ROS) and core storage. The ROS can contain data for alpha-numeric printing, while the printing of special characters such as Katakana is controlled by the retrieving of bytes from core storage. Operation is on a cycle-steal basis and the attachment includes the logic circuitry for inspecting each data byte retrieved in the program execution, to decide whether the ROS or core storage will be used for wire firing control signal generation. This arrangement permits relatively easy interchanging or customizing of character sets, such as by defining special symbols for graph plotting.

The programmer initially enters a series of bytes which represent print hammer command signals in a core storage table, as shown in Fig. 1, where the first byte address is "S" and the last byte address is "S + 9N - 1". The number of special characters being entered determines the width N of this table. The table of Fig. 1 is arranged to illustrate that all of bytes required to print one symbol are in a fixed relation to each other, T1 through T9. The strings of bytes of Table 1 typically are contained in serial manner in core storage, rather than the vertical arrangement as shown. Displacement D is the distance from the first address to the first byte of a character to be printed. D is defined by the bits of the weighted code assigned to a particular symbol. The wire matrix print hammer bits for a given symbol are stored in the table at addresses S + D, S + N + D, S + 2N + D,
... and S + 8N + D.

Attachment 32 communicates with CPU 30 on a cycle-steal basis. Local storage registers PDAR 33 and CIAR 34 are used to address core storage for print data and character image information, respectively.

These registers are program loaded to contain the starting address of the data and character image fields. A print command directs attachment 32 to cycle steal a byte of data from the data field.

This data character is placed in the PDR 35 and remains there for the duration of one print position. The data character is interrogated by the character image control logic 36 to direct the character dot pattern to be generated by ROS 37, or to be read from core storage 38 via 11, 12, 14 and 13 into the print wire register 39. This register selects which dots in a column are to be printed. A timing emitter 29 indexes print dot location counter 42 which, in turn, determines which vertical column of the dot pattern is to be printed. Pulses for the hammer coil drivers are produced on output 28. Although only one output 28 is shown, there is an additional such output and its associated control logic for...