JPS62279441A - Memory system for microcomputer - Google Patents

Abstract

PURPOSE:To improve the degree of freedom of program constitution and to process and control at high grade function by providing areas for program and areas for data in a common address area of each memory, and at the same time, providing plural area selecting and setting means. CONSTITUTION:Plural areas for program P0-P3 and plural areas for data D0-D3 are set in each common address area of a main memory M' and an extended memories X1'-X3'. A column register for program CR and a column register for data DR latch selection data outputted independently from a microprocessor MPU by I/O instruction. Accordingly, areas P0-P3 and D0-D3 become accessible in an alternative way, and data storage areas directly accessible from each column are sufficiently ensured without reducing address space of each column. Thus, the degree of freedom in constituting a program can be heightened, and highly functional processing and controlling can be made.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention 1 (Field of Industrial Application) The present invention relates to improvement of a memory system of a microcomputer.

(Prior Art) In recent years, microcomputers have come to be widely used in everything from cutting-edge equipment such as electronic private branch exchanges and facsimile machines to household electrical appliances. Generally, a microcomputer has a microprocessor (
MPLI) with memory, I10 board, etc. connected to it, and the maximum capacity of memory that can be directly accessed is defined by the number of address bits of the microprocessor.

However, with stored program type devices such as electronic private branch exchanges, it may be necessary to expand the program each time in response to requests for additional functions after installation.
In such a case, in a memory system where the maximum capacity is defined by the address of the microprocessor as described above, the program storage capacity may be insufficient.

Therefore, in the past, for example, as shown in FIG. 3, a main memory M (address 0
64 bytes represented by 000H-, -FFFFH)
In addition, at least one (four in the figure) extended memory X1. X
2. The memory space is expanded by providing a column register OR for selectively setting these expansion memories x1 to x3 and the address shared area XO of the main memory M to be accessible.

With this configuration, selection data is set in the column register CR by a 110 instruction from a microprocessor (MPU) not shown, and this sets the selection data in the address shared area of the main memory M and each expansion memory (initiated column XO
By selectively selecting ``XO~x3'', it becomes possible to access all the programs and data stored in each column XO~x3, thereby increasing the usable memory space to 64 bytes. It is possible to significantly expand the memory capacity from 160 to 160 bytes to eliminate the shortage of memory capacity.

However, such a memory system requires that each column
Since ○ to ×3 are accessed selectively, for example, as shown in FIG. 4(a), column x1 is selected by column register CR and program A stored in this column is executed. When the data is stored in the same column x 1 or the data or program stored in the independent area WO of the main memory M can be accessed, but other columns XO, X1° x 3 can be accessed.
The data C etc. stored in the ``data'' cannot be accessed. For this reason, the data that needs to be accessed from each column X0-X3, for example, is
As shown in data D in b), all data must be stored in the independent area WO of the main memory M. However, if this is done, the system program for initializing the microprocessor, interrupt processing, etc. is stored in the independent area WO of the main memory M, and only the remaining area can be used for data storage. There was a problem that the data storage fI4m was significantly insufficient.

On the other hand, in order to solve this problem, it is conceivable to increase the independent area WO' of the main memory M, for example, as shown in FIG. As a result, there is a problem in that the size of the program stored in each column is greatly limited.

(Problems to be Solved by the Invention) As described above, the conventional memory system has the problem that it is not possible to secure sufficient data storage area and storage area for each column. With this in mind, we have made it possible to secure a sufficient data storage area that can be directly accessed from each column without reducing the address space of each column, thereby increasing flexibility in configuring programs and achieving high performance. It is an object of the present invention to provide a microcomputer memory system capable of processing and controlling.

[Configuration of the Invention (Means for Solving Problems) The present invention provides a plurality of program areas and a plurality of data areas respectively set in each common address area of the main memory and extended memory, and First and second area selection setting means are provided for each of the storage area and each data area, respectively, and selection data is individually set in the first and second area selection setting means by a predetermined command from the microprocessor. As a result, each program area and each data area can be set to be accessible alternatively and independently of each other.

(Function) As a result, each data area set in the main memory and extended memory can be directly accessed from the program area in either the main memory or extended memory by a predetermined command of the microprocessor, and as a result, each It is possible to secure a sufficient capacity of data storage area that can be accessed directly from the column. In addition, since the data area is added to each program area in the main memory and extended memory, the capacity of each program area can be secured without reducing the capacity, which limits the size of the program. This eliminates the need to do so, and in conjunction with the increase in data storage capacity, the degree of freedom in creating programs can be greatly increased.

(Embodiment) FIG. 1 is a schematic diagram of a memory system according to an embodiment of the present invention, and this system includes a main memory M' and three expansion memories X1' to X3'. First, the main memory M' has a 16-bit address (OOOOH-FFFF
H) has a storage area of maximum capacity (64 bytes) that can be accessed by WO'. and data area (4000H to 7FFFH)D.

and program area (8000H to FFFFH) P
It is divided into O. On the other hand, each expansion memory X1' to X3'
has a storage area of the same capacity and address set in common with the data area DO and program area PO of the main memory M', and has data areas D1 to D3 and program areas P1 to P3, respectively. divided into

The system of this embodiment also includes a program column register OR and a data column register DR. These column registers CR.

DR is a microprocessor (MPIJ), both not shown.
) is used to latch the selection data outputted independently from each other by the I10 instruction, and each of the program areas PO to P3 and each data area Do to D3 can be accessed alternatively according to these selection data. do. The data areas Do to D3 and the program areas PO to P3 are selected by, for example, supplying a predetermined signal to a chip select terminal provided in the memory.

Because of this configuration, suppose now that the program area P1 is selected by the program column register CR and the program area P2 is selected by the data column register DR, as shown in FIG. 2 (a). At this time, while executing the program A stored in the program area P1, the microprocessor also uses the storage area in the same area P1 and the storage area in the independent area WO of the main memory M'. The data area D2 can be accessed directly, thereby processing the data stored in this area D2.

Additionally, if it is necessary to access data stored in another data area, for example data area D3, while executing program A, execute the I10 instruction in program A before accessing this data. Selection data for causing the data column register DR to select the data area D3 is output. Then, the data area D3 is selected and becomes accessible as shown in FIG. 2(b) in place of the data area D2 that had been selected by the data column register DR. By executing a data transfer command and accessing any area within addresses 4000H to 7FFFH, the data stored in this area can be transferred.

Therefore, in this embodiment, the microprocessor is
By causing the data column register DR to select a desired data area using the 10 instruction, all of the above data areas D can be selected even when the program in any of the program areas PO to P3 is being executed.

~D3 can be freely and directly accessed, and as a result, a sufficient capacity of the data area can be secured without reducing the program area.

Therefore, it is possible to freely create a program in response to additional requests for performance, etc., without worrying about the size.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, a case has been described in which an independent area is set in the main memory M', but if an independent area is not required, this independent area may also be set as a data area. In this way, the data area of the extended memory can be increased, so the overall capacity of the data area can be increased. In addition, as the area selection setting means, a decoder or the like may be used in addition to the register, and the capacity of the Shinji memory, the number of expansion memories, the ratio of the program area and the data area, etc. also deviate from the gist of the present invention. It can be implemented with various modifications within the scope.

[Effects of the Invention] As detailed above, according to the present invention, a plurality of program areas and a plurality of data areas are set in each common address area of the main memory and extended memory, and these program areas First and second area selection and setting means are provided for each data area, and selection data is set separately in the first and second area selection and setting means by a predetermined command from the microprocessor. By setting each program area and each data area to be mutually independent and selectively accessible,
Enough data storage area can be secured that can be directly accessed from each column without reducing the address space of each column, which increases flexibility in configuring programs and enables high-performance processing and control. A memory system for a microcomputer can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a memory system according to an embodiment of the present invention, FIGS. 2(a) and (b) are schematic diagrams used to explain the operation of the same system, and FIG. 3 is a diagram of a conventional memory system. FIGS. 4(a) and 4(b) are schematic diagrams used to explain the operation of the system, and FIG. 5 is a schematic diagram of another conventional memory system. M'...Main memory, X1' to X3'...Extended memory, Wo...Independent area of main memory, Do to D3...
Data area, PO-P3...program area, program column register CR, OR...data column register. Applicant's agent Patent attorney Takehiko Suzue "-111cho1="-"1 Figure 46 (a) Figure 4 (b) MPtJ?5 Figure 5

Claims (1)

[Claims] A memory system for a microcomputer comprising a main memory whose maximum capacity is defined by an address of a microprocessor, and at least one extended memory having a common address with all or part of this main memory, wherein the main memory and the extended memory have a common address. A plurality of program areas and a plurality of data areas are respectively set in each common address area of the memory, and each of the program areas and each data area is selected independently from each other by a predetermined instruction of a microprocessor. 1. A memory system for a microcomputer, comprising first and second setting means for setting the memory to be accessible.