JPH02122963A - Printer - Google Patents

Abstract

PURPOSE:To shorten time required for replacement of program memory by providing a program memory selection device which connects a signal generated by a detection device to a signal generated by a microprocessor and selects either one of the first block or the second block in program memory for signal generation. CONSTITUTION:A program memory detection device 7 detects whether program memory 6 exists or not according to the state of a signal (f). A program mem ory selection device 7 selects either one of the blocks 2, 6 in program memory for generation of a memory selection signal which is one type of control signal (c), according to a signal (g) generated by the program detection device 7. That is, the voltage level of the signals f, g varies depending on the case where the block 6 in program memory is mounted or the case where the block 6 is not mounted. The program memory selection device 8 transmits a memory selection signal to a signal (d) connected to the block 2 in program memory 2 or a signal (e) connected to the block in program memory 6, depending upon said voltage level. Consequently, the block in program memory which is read by a microprocessor 1 is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printer device, and more particularly to a control circuit for a printer device.

[Conventional technology]

Conventionally, in this type of printer device where an expansion program memory can be added to increase storage capacity, the expansion program memory is used to compensate for the lack of main program memory, and is separate from the main program memory. The main program memory and additional program memory could both be read from the microprocessor.

[Problem to be solved by the invention]

In the conventional printer device described above, when it becomes necessary to replace the main program memory, even if the storage element can be replaced by using an IC socket, the main program memory cannot be installed from the printer device. It was necessary to remove the printed wiring board and replace the memory element/device, which required complicated work.

[Means to solve the problem]

The printer device of the present invention includes means for additionally mounting a second program memory different from the first program memory, means for detecting the addition of the second program memory, and a signal generated by the detection means. and a program memory selection means connected to the signal generated by the microprocessor and selecting between the first program memory and the second program memory to which the signal is generated.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic circuit diagram of an embodiment of the present invention.

Microprocessor l has address bus a and data bus b.
and a control signal C, reads an instruction stored in the program memory 2, interprets the meaning of the instruction, and executes the instruction. When a command is to read or write data from a circuit connected outside the microprocessor 1, the command is executed by controlling the address bus B, data bus B, and control signal C. The program memory 2 is a readable storage element in which instructions for controlling the operation of the microprocessor 1 are written in advance. The character pattern memory 3 is a readable storage element that stores information on the shape and two colors of characters to be printed, and the microprocessor 1 can read out the contents. The printing mechanism control circuit 4 is a signal controlling means for the printing mechanism 50, and is in charge of monitoring the status of the printing mechanism 5 and sending out operation instruction printing data.

The microprocessor 1 controls the printing mechanism 5 through signals by writing to and reading from memory elements, registers, buffers, etc. that can be written to and read from in the printing control mechanism 4.

Generally, microprocessor 1 reads a character pattern from character pattern memory 3 and writes this character pattern to printing mechanism control circuit 4. The printing mechanism control circuit 4 motivates the operation of the printing mechanism 5 to send this character pattern to the printing mechanism to obtain a printing result on paper. The program memory 6, like the program memory 2, is a readable storage element that stores instructions for the microprocessor 1. However, program memory 2 is
The program memory 6 is mounted on a control circuit board within the printer device from the time of shipment in order to control the printer and operate it as a printer, but the program memory 6 is not always present in the control circuit of the printer device. The difference is that it is implemented only when necessary. That is, the program memory 6 is either mounted on an auxiliary control circuit board that is connected when necessary to a connector etc. prepared on a control circuit board mounted in the printer device from the time of shipment, or it is installed in the printer device from the time of shipment. This is a memory element mounted in a spare IC socket prepared on the mounted control circuit board. Therefore, FIG. 1 shows a circuit diagram when this program memory 6 is mounted on a control circuit board by such means.

The program memory detection means 7 is means for detecting that the program memory 6 is installed, and detects the presence or absence of the program memory 6 based on the state of the signal f. The program memory selection means 8 sends a memory selection signal, which is a type of control signal C, to the program memory 2. This is means for selecting in which part of the program memory 6 the data will be generated. That is, the voltage levels of the signal f and the signal g are different depending on whether the program memory 6 is installed or not, and the program memory selection means 8 selects the signal d connected to the program memory 2 depending on the voltage level. The microprocessor 1 selects the program memory to be read by propagating a memory selection signal or by propagating a memory selection signal to the signal e connected to the program memory 6.

FIG. 2 shows a specific circuit example of the program memory 2° program memory 6, program memory detection means 7, and program memory selection means 8 in the present invention. The program memory 6 is mounted on the auxiliary control circuit board 16 as in the example described above, and signals connected to the program memory 6 are connected via connectors 11 to 15. The program memory 2 and the program memory 6 each have an address signal input, a data signal output, a data output permission signal input that is activated at 0 level, and an element activation signal input that is activated at 0 level. , data bus b, and output enable signal are connected to memory selection signals n and p.

FIG. 3(a) shows a timing chart of input signals and output signals of the program memory. The microprocessor 1 generally generates a signal in synchronization with a clock, and several cycles of this clock correspond to the cycle of one instruction. Here T is 1
One write or read operation is completed in four cycles. Microprocessor 1 generates a memory address to be written or read on address bus a, and generates a 0 level pulse in memory selection signal 1 and output enable signal k. Program memory generally does not generate data at the data signal output unless both the element activation signal input and the data output permission signal are activated. Therefore, a data signal is output to data bus b only from the program memory to which memory selection signal 1 and output enable signal k are applied. Microprocessor 1 is data bus B
Normally, the data output to the controller is latched into an internal register and instructions such as calculations are executed.

Returning to FIG. 2, the output signal n of the logical branch circuit 18 is connected to the element activation signal input of the program memory 2, and the output signal p of the OR circuit 17 is connected to the element activation signal input of the program memory 6. There is. One of the input terminals of the OR circuits 17 and 19 is both a memory selection signal l, and a signal j
Alternatively, only the OR circuit in which m is O level can propagate a 0 level pulse to the program memory.

The program memory detection circuit 7 is grounded 9. 10. Resistor pulled up to power supply. Grounded signal i, connector 11.
and a signal j that connects the logger 11 and the logic NOT circuit 18. When the auxiliary control circuit board 17 is not connected, the signal line j is not grounded, so the voltage level is approximately equal to the power supply voltage and becomes a logic level, and the output signal m of the logic NOT circuit 18 becomes a logic O level. On the other hand, when the auxiliary control circuit board 16 is connected, the signal line j is grounded by the signal i, so the voltage level is almost equal to the ground potential, and now this means a logic 0 level, so the output of the logic NOT circuit 17 The signal m becomes a logical level.

Therefore, as shown in FIG. 3(b), the auxiliary control circuit board 1
6 is not connected, the pulse signal of the memory selection signal 100 level reaches only the element activation signal input of the program memory 2, and only the data of the program memory 2 is output to the data bus C. Conversely, as shown in FIG. 3(C), when the auxiliary control circuit board 16 is connected, the 0-level pulse signal of the memory selection signal l reaches only the input terminal of the program memory 6, and the program memory Only data No. 6 is output to data bus b. That is, when the auxiliary control circuit board 16 is not connected, the microprocessor 1 operates by reading only instructions stored in the program memory 2, and when the auxiliary control circuit board 16 is connected, the microprocessor 1 reads instructions stored in the program memory 6. Only the stored instructions can be read and operated.

〔Effect of the invention〕

As explained above, by using the present invention, when it becomes necessary to replace the program memory of the microprocessor built in the printer device after shipping, it is possible to replace the program memory with a new program memory or with the auxiliary control circuit equipped with the new program memory. By simply mounting an additional board, a new program memory can be attached to a printer device that has already been shipped to a user, and the printer device can be operated with the new program memory installed. That is, there is no need to remove the old program memory, which was conventionally necessary, and therefore the time required to replace the program memory can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a control circuit of a printer device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing details of a program memory, program memory detecting means, and program memory selecting means according to an embodiment of the present invention. , FIG. 3 is a timing chart showing an example of read timing of the program memory. DESCRIPTION OF SYMBOLS 1... Microprocessor, 2... Mark/first program memory, 3... Character pattern memory, 4... Printing mechanism control circuit, 5... - Printing mechanism, 6... Group - Second program memory, 7...
. . . Program memory detection means, 8 . . . Program memory selection means, 9 . . . Grounding, lO.
...Resistance, 11-15 ...Connector, 16
...OR circuit, 17...Logic NOT circuit, 18...OR circuit, a...address bus, b...data Bus, C...
Control signal, d... Selection signal for program memory 2, e... Selection signal for program memory 6, f
...Detection signal of program memory 6, g...
...Detection signal of program memory 6, h...
Printing mechanism control circuit, i...Program memory 6
Detection signal of j...Program memory 6 detection signal, k...Output enable signal, ■
...Memory selection signal, m...Program memory 6 detection signal, n...Memory selection signal, p...Memory selection signal. Agent Patent Attorney Uchihara Onbe 1 Zukan 2

Claims (1)

[Claims] a first program memory for storing operating procedures of a microprocessor; a character pattern memory readable by the microprocessor; a printing mechanism for recording characters and figures on printing paper; and the microprocessor controlling the printing mechanism. In the printer device, the printer device includes a printing mechanism control means for additionally mounting a second program memory different from the first program memory, and a means for detecting that the second program memory is added. and a program memory selection means which connects the signal generated by the detection means and the signal generated by the microprocessor and selects whether the signal is generated in the first program memory or the second program memory. and operates according to the program stored in the first program memory when the second program memory is not installed, and operates according to the program stored in the second program memory when the second program memory is installed. A printer device that operates according to a stored program.