JPH01304563A - Single chip microcomputer - Google Patents

Abstract

PURPOSE:To reduce the cost by storing table data, which is cited in an application program, in a PROM part. CONSTITUTION:A program memory 1 consists of a mask ROM part 2 and a PROM part 3, and the application program is stored in the ROM part 2, and table data is stored in the PROM part 3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a single-chip microcomputer with a built-in ROM for storing application programs, and in particular, the structure of the built-in ROM includes a mask ROM and a PROM. It's about being.

[Conventional technology]

Conventionally, in this type of single-chip microcomputer, when data referenced in an application program is made into a table, all the table data is placed in a ROM in which the program itself is stored. Moreover, all of these ROMs are mask ROMs or all of them have a PROM structure.

[Problem to be solved by the invention]

The conventional single-chip microcomputer mentioned above has a built-in ROM that is all bit mask ROM or PRO.
It's M. For this purpose, if we try to prepare a single-chip microcomputer with a wide variety of products in small quantities for different destinations by changing only the table data in the application program, the former mask ROM type will require only a small amount of mask ROM. Depending on the type, the cost will be higher.

0 On the other hand, in order to mass produce, each destination has a large capacity ROM when the table data is combined into one.
becomes necessary.

There is a drawback. On the other hand, with the latter PROM type, ORO
Since all M bits are PROM, it is suitable for small quantity production, but it is more expensive than a mask ROM part of the same capacity.

0 The application program takes a long time to program because all table data is written electrically.

There is a drawback.

[Means to solve the problem]

The single-chip microcomputer of the present invention has: (a) a mask ROM section that stores an application program; and (b) a PROM section that stores table data referenced in the application program.

In the mask ROM part of a, a program common to each destination can be written in advance as a mask and kept in stock. Then, as necessary, the destination writes separately excited table data to the PROM portion, allowing a large variety of products to be produced in small quantities.

〔Example〕

FIG. 1 shows an embodiment of the present invention.

In this example, a case is shown in which a PROM that stores table data is placed in a program memory.

1 is a program memory, which includes a mask ROM section 2 that stores application programs and a PR that stores table data.
It consists of an OM section 3.

The CPU 4 reads and operates the program in the mask ROM 2 via the internal BUS 5, and proceeds with the process while quoting the table data in the PROM 3 as necessary.

FIG. 2 is a block diagram of a second embodiment of the present invention.

In this example, a case is shown in which a PROM that stores table data is arranged independently of the program memory.

A program memory 6 stores application programs and has an all-bit mask ROM structure. A memory 7 stores table data and has an all-bit PROM structure.

Similar to the first embodiment, the CPU 8 reads the program from the program memory 6 via the internal BUS 9 and operates while quoting data 7 as necessary.

In this embodiment, the PROM part that stores table data is arranged independently from other memories, such as program memory, so that
ROM programming has the advantage that it can be handled simply as data writing to a small-capacity PROM.

〔Effect of the invention〕

As explained above, the present invention provides a PROM memory that stores table data referenced in an application program.
structure and mask R the memory that stores the program itself.
By using OM, when preparing a separately-excited single-chip microcomputer by changing only the table data, it is possible to handle a wide variety of products in small quantities, something that mask ROMs are not good at, while making it possible to handle all-bit PROM products. This has the advantage of not increasing costs. Also, all
(Pi) It has the advantage that the programming time is shorter than that of PROM products.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a first embodiment of the single-chip microcomputer of the present invention, and FIG. 2 is a block diagram of a second embodiment of the present invention.
FIG. 1... Program memory, 2... Mask ROM section for storing application programs, 3... PROM section for storing table data, 4... CP
U, 5... Internal BUS, 6... Program memory (mask ROM), 7... Table data memory (PROM), 8... C
PU, 9...Internal BUS. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] A single-chip microcomputer characterized in that when fixed data referenced in a user's application program is tabulated, the memory structure for storing the table data is a PROM structure. Computer.