JPH0976580A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously perform the operation of font data and the command fetch of a CPU. SOLUTION: A font developing part 13 performs the operation of font data such as font development performed heretofore by a CPU and a font ROM 14 is connected to a bus 17 for the font ROM separated from a CPU bus 16. A font developing part 13 reads font data from the font ROM 14 and, at the same time, a CPU 11 performs the fetch of the command from an ROM 12 for CPU command data and the access to an RAM 15 in parallel. Therefore, high speed operation becomes possible. The CPU 11 can perform the reading of a font from the font ROM 14 through the font developing part 13. Further, by connecting an RAM 18 for operating font data to the bus 17 for the font ROM, the data operation accompanied by the writing operation to the RAM of the font can be performed without obstructing the operation of the CPU.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus, and more particularly to a technique for configuring a memory area of a memory arranged around a CPU in the printing apparatus. The present invention is a laser beam
It is suitable for a printing device such as a printer that performs high-speed data processing.

[0002]

2. Description of the Related Art The following is a method of forming a memory area of a memory arranged around a conventional general CPU (central processing unit). First, as the most basic form, there is a system in which all memories are arranged on the same CPU bus. While this method can be realized at a relatively low cost and the system configuration is simple, it may be inconvenient in a system that performs high-speed data processing. For example, a device that wants to handle a memory other than a CPU on the system, such as a sub CPU, I that handles a large amount of data at high speed
/ F (interface) exists and the device frequently accesses the memory.
In this case, of course, the occupation rate of the CPU bus by the device other than the CPU becomes high, and thus the performance of the CPU may deteriorate.

Conventionally, there is an example in which memory is separated in order to avoid such an inconvenience. This separates ROM (Read Only Memory) and RAM (Random Access Memory). CP is used for the CPU side bus.
The ROM storing the U instruction is arranged, and the RAM is arranged on the other device side.

[0004]

On the other hand, in the inside of the laser beam printer, drawing processing is performed based on drawing data (drawing language, image data, etc.) sent from the host computer, and an electrophotographic recording system is used. To print on recording paper. Therefore, the printer itself often has the font. Basically the CP inside the printer
U performs font data expansion, but in order to realize a high-speed system configuration, font data operations (expansion, rotation, compression, expansion) may be performed by a dedicated device. In this case, if the data to be operated and its work area exist in the RAM, the memory area configuration by separating the above-mentioned RAM and ROM, which has been conventionally used, causes C
It should be possible to avoid interfering with PU bus usage.
However, since the font is generally stored in the ROM, the instruction fetch operation of the CPU is hindered when operating the font data in the conventional memory area configuration in which the RAM and the ROM are separated.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a printing apparatus capable of simultaneously operating font data and fetching a command from a CPU.

[0006]

In order to achieve the above object, the present invention provides a CPU that controls the arithmetic operation of the entire apparatus, and a CPU that connects the CPU with a memory and peripheral devices.
A bus, a font expansion unit connected to the CPU bus for operating a font that is character shape data under the control of the CPU, and the font data separated from the CPU bus and read by the font expansion unit are stored. And a font ROM bus connecting the font ROM and the font expanding unit.

As one form of the present invention, the CPU can read the font from the font ROM through the font expansion unit.

As another form of the present invention, a RAM for operating font data can be connected to the font ROM bus.

In the present invention, as described above, the font expansion unit performs the operation of the font data such as the font expansion conventionally performed by the CPU incorporated in the printing apparatus, and the font is stored in the font ROM bus separated from the CPU bus. Since the font ROM is connected, the font expansion unit reads the font data from the font ROM and at the same time the CPU
Instructions can be fetched from the instruction data ROM and access to the RAM can be performed in parallel, which enables high-speed operation. In addition, the CPU reads the font to RO for the font.
It can be done from M through the font development part. Further, by connecting the RAM for font data operation to the font ROM bus, data operations involving a write operation to the font RAM can be performed without disturbing the operation of the CPU.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows the configuration of a first embodiment in which the present invention is applied to a laser beam printer (hereinafter referred to as LBP). The memory in the controller that performs high-speed data processing in the LBP is usually ROM or R
The present invention relates to the structure of the ROM, which is composed of an AM and the like. In FIG. 1, 11 is a CPU that controls the overall arithmetic control of the LBP, and 12 is a CPU command data ROM that stores the instructions (commands) of this CPU. Reference numeral 13 is a font expansion unit which is a dedicated device for operating (font expansion, rotation, compression, expansion) a font which is character shape data, and 14 is a font ROM which stores the font data. Fifteen
Is a RAM used as a work area of the CPU 11 or a drawing data area, 16 is a CPU bus that connects the CPU 11 to the memory and peripheral devices, and 17 is a font ROM
It is a bus for font ROM that connects 14 and the font expansion unit 13.

In the configuration shown in FIG. 1, the font expansion unit 13 performs the operation of font data such as the font expansion conventionally performed by the CPU, and the font ROM 1 is used.
Bus 1 for font ROM separated from CPU bus 16
It is connected to 7. By adopting such a configuration, the font expanding unit 13 reads the font data from the font ROM 14, and at the same time, the CPU 11 fetches an instruction from the CPU instruction data ROM 12 and the RAM 15
Will be able to access in parallel. As a result,
High-speed operation becomes possible. Further, the CPU 11 reads the font from the font ROM 14 and loads the font into the font expansion unit 13
Can be done through.

(Second Embodiment) FIG. 2 shows the present invention as an LBP.
2 shows a configuration of a second embodiment applied to. In FIG. 2, 11 to 17 are the same components as those of the same reference numerals in FIG. 18 is font data operation (font expansion,
This is a font RAM for font compression / decompression) and is connected to the font ROM bus 17.

In the configuration shown in FIG. 2, the font expansion unit 13 performs font data operations such as font expansion, and the font ROM 14 and font RAM 18 are CP.
It is connected to a font ROM bus 17 separated from the U bus 16. By adopting such a configuration, as described in the first embodiment, it is possible to allow the font development unit 13 to read the font data and access the CPU 11 in parallel, and at the same time to use the font RAM 18. Data operations (such as data writing after font expansion and data writing after font compression / expansion) accompanied by a font write operation to the RAM can be performed without disturbing the operation of the CPU 11. As a result, higher speed operation becomes possible.
Further, the CPU 11 can perform a font read from the font ROM 14 and a read / write operation to the font RAM 18 through the font expansion unit 13.

(Other Embodiments) The present invention may be applied to a system including a plurality of devices or an apparatus including a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus. In this case, by reading a storage medium storing a program represented by software for achieving the present invention into the system or the apparatus, the system or the apparatus can enjoy the effects of the present invention. Becomes

[0016]

As described above, according to the present invention, the ROM is the CPU command data ROM and the font R.
Since it is separated into the OM and this font ROM is connected to the font ROM bus separated from the CPU bus via the font expansion unit for operating font data such as font expansion, a CPU that cannot be performed in the conventional system. R
The instruction fetch from the OM and the reading of the font data can be performed at the same time, and the high speed operation of the system can be achieved.

Further, according to the present invention, by further connecting a font RAM for font data operation (font expansion, font compression / expansion) to the font ROM bus, data accompanying a write operation of the font RAM is performed. Operations (data writing after font expansion, data writing after font compression / decompression, etc.) can also be performed without disturbing the operation of the CPU, and the effect that the system can operate at higher speed is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment in which the present invention is applied to an LBP and showing a configuration example in which a CPU command data ROM and a font ROM are separated.

FIG. 2 is a second embodiment in which the present invention is applied to LBP, in which a font R is provided on a separate font ROM bus.
It is a block diagram which shows the structural example which mounts AM.

[Explanation of symbols]

 11 CPU 12 CPU instruction data ROM 13 Font expansion unit 14 Font ROM 15 RAM 16 CPU bus 17 Font ROM bus 18 Font RAM

Claims (3)

[Claims] 1. A CPU that controls arithmetic operation of the entire apparatus, and a CP that connects the CPU with a memory and peripheral devices.
A U-bus, a font expansion unit connected to the CPU bus for operating a font that is character shape data under the control of the CPU, and the font data separated from the CPU bus and read by the font expansion unit. A printing apparatus comprising: a font ROM stored therein; and a font ROM bus connecting the font ROM and the font expansion unit. 2. The printing apparatus according to claim 1, wherein the CPU can read the font from the font ROM via the font expansion unit. 3. The printer according to claim 1, wherein a RAM for operating font data is connected to the font ROM bus.