JPH03189836A - Portable information device - Google Patents

Abstract

PURPOSE:To easily execute the correction and the change of a program by storing the program for a portable information device onto a RAM backed up by a battery, inhibiting forcibly a write signal of its RAM at the time of using it actually, and using it equally with such a program as written in a ROM. CONSTITUTION:A RAM 3 is provided instead of a ROM in which a program, etc., are contained, and the RAMs 3, 4 are always backed up by a battery by using a sub-battery 9. Also, a write signal of the RAM 3 is pulled up to a backed-up potential VBAT by a resistance, and it becomes a write inhibited state. In the case of writing the program, etc., in the RAM 3, it can be used equally with the ROM by setting it in advance to a state that a write signal is inputted by a switch and an external circuit, controlling directly address and data buses from the outside, or writing data in the RAM 3 through an I/O control circuit 2, and thereafter, inhibiting the write signal. In such a way, the program and data can be corrected and changed freely.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a portable information device.

[Summary of the invention]

The present invention stores a program in a portable information device on a battery-backed RAM, and forcibly inhibits the write signal of the RAM during actual use, making it appear as if it were an R.
The program is used in the same way as a program written in the OM, so that it is not only easy to modify and change the program, but also allows the program to be used without losing its contents even if the program goes out of control.

[Conventional technology]

A circuit block diagram of a conventional portable information device is shown in FIG.

cpui, ro control circuit B2. It is composed of ROM1 and RAM4. Here, to simplify the explanation, we assume that the CPU is a general Z80 (registered by Zilog &M). The signal name is not limited to the 8-bit CPU, but may be 4-bit or 16-bit CPtJ, but since the signal name etc. changes depending on the CPU, the signal name of Z80 will be used in the following explanation.

In FIG. 7, programs and data are written in the ROM 7, and the CPU operates according to the programs.

The programs in ROM 7 may include all the programs necessary for the portable information device, or the basic parts may be written, and the remaining programs and data may be written in ■
It may also be downloaded from the external device 20 to the RAM 4 via the 0 system doorway 2. RAM4 is back-amplified by an auxiliary battery as necessary.

As the ROM7, EPROM (erasable FROM) is used in boat fishing equipment, but in portable information devices, MROM (mask ROM), 0ne-TimeFROM ( FROM, which cannot be erased, is often used.

FIG. 8 is a general circuit diagram of the control circuit 5 shown in FIG. CE (chip select) signals for ROM7 and RAM4 are generated from the MPEO signal and address among the CPUI signals. ROM7 is 0OOOH~7FFFH,
RAM4 is selected at addresses 800H to FFFFH.

[Problem to be solved by the invention]

The conventional technology has the following problems.

When all programs and data have been written to the ROM, there is a very big advantage that it will operate normally immediately after a reset in any case.
It is difficult to modify or change the content.

If MROM is used as ROM, then -
The MROM must be remade every time, which requires masking and a development period of 1 to 3 months. Also O
When a ne-TimeFROM is used, program changes can be made flexibly before manufacturing, but once manufactured, the One-TimeFROM must be replaced. Due to diameter constraints, the elements are soldered directly to the board using a surface mount method. Therefore, in the case of ROM replacement, disassembly - ROM
Removal - ROM installation requires a series of procedures including one assembly and one inspection, which requires time and labor, and is not desirable in terms of quality, such as peeling of the pattern on the board. Since One-Time FROM cannot be regenerated, there are problems such as extra costs for parts each time it is replaced.

A basic program is stored in a part of the ROM, and the RA
In the method of downloading the remaining programs etc. to M, R
There is an advantage that the program on AM can be freely rewritten. Programs suitable for the user's specifications, called user programs, application programs, etc., are often written in RAM. However, R
Since there is a program in A M, there is a bug in the program,
The program may be rewritten due to malfunction, runaway due to external noise, etc., or carelessness in use such as incorrect operation, and each time the program is rewritten, the program must be downloaded again. If the necessary means for downloading is not available, the program may become unusable. Put it away.

At the time of design, consideration is given to which part of the program should be included in the ROM, and in many cases the basic input/output control part and routines common to the user program and application program are included.

However, in this case, when a situation arises that requires modification or change of the ROM section, the ROM still needs to be replaced.

[Means to solve the problem]

SUMMARY OF THE INVENTION An object of the present invention is to provide a portable information device in which the program can be easily changed without the need to replace the ROM, and the program is not destroyed even by runaway.

For that, Buffaluff.

The RAM write signal is C
It cannot be controlled by the PU and can be permitted by an external circuit or an external operation.

[Effect]

When writing a program, etc. to RAM, a write signal is input by a switch or an external circuit, and the address data bus is controlled directly from the outside, or the hollJf
By writing data into the RAM through one circuit and then disabling the write signal, it can be used in the same way as a ROM.

〔Example〕

Next, examples of the present invention will be shown.

FIG. 1 is a block diagram showing an embodiment of the portable information device of the present invention.6 This embodiment is a R
RAM3 is provided instead of OM. The RAM 3.4 is always connected to the sub-battery 9.

Here, RAM4 does not necessarily need to be a bank amplifier. The BUSRO (bus request) signal of the CPU is pull-amplified, and the WR (write-write) signal of the RAM 3 is pulled up to the backed-up potential VBAT by a resistor, so that writing is prohibited.

FIG. 2 is a circuit diagram showing a part of the control circuit 5B shown in FIG. 1, in which the CE, RD (read-read signal), and WR portions of the RAM 3.4 are extracted. Here, when the voltage of the main battery 8 drops, the operation of the CPU is stopped, access to the RAM 3.4 is prohibited, and the backup mode is entered.

This state is a reset after the main battery 8 is replaced, N1v
This continues until l+ (non-maskable included interrupt), INT (included interrupt), etc. are manually input.

FIG. 3 is a diagram showing the connection with the writing device 10 when writing to the RAM 3. In this case, it is assumed that writing is performed during the manufacturing process. First, CPU BU
By setting SRO to 6L'', the writing device 10 can access the address bus A, data bus D, and control bus of the portable information device 2o.
Occupies part of the ill line.

Next, the writing device 10 is connected to address bus A and data bus D.
Data can be written to RAM 3 by adding more signals and dropping MREO, RAM 317) WR to L. If it is necessary to verify the written data, set MREORD to “L”.
AM3 data can also be read. Writing to RAM3 can be done near the end of the manufacturing process. For example, this is done with a jig set just before attaching a case to a part of a portable information device.

FIGS. 4 and 5 are a circuit diagram and a memory map showing an embodiment of the loading device used in the present invention. Here, the RAM 3 is 256 kbits (32 kbits high), and the mask ROM 13 has data to be written to the RAM 3. CPU11 from 8000H to FFFFH
By reading the addresses up to and including the mask R from the mask ROM 13 and writing them to the same addresses, the mask R is stored in the RAM 3.
The same data as OM13 can be written. However, the memory map of RAM3 is 8 in the S writing device 10.
The range is from 000H to FFFFH, but for portable information devices it is from 0OOOH to 7FFFH.

FIG. 6 is a block diagram showing another embodiment of the portable information device of the present invention. This embodiment corresponds to a method in which a program is loaded after assembly as a product. R
AM3 is disabled and the WR double signal normal switch 21 is turned off, so it is inactive (“
H") and cannot be written. The ROM 7 contains a program that performs the basic operations of the IO$ control circuit 20. The CPU 10 control circuit 2
It is possible to communicate with the external device 22 via.

Here, the switch 21 is a switch that can be turned ON10 F F from the outside, and is a mechanical S for boat fishing.
W may be used, but lead SW may also be used. While the switch 21 is kept on, programs and the like are downloaded to the RAM 3 by the external device 22, and then the WR multiplication signal is prohibited by turning off the switch 21. Of course, downloading can also be performed to RAM4.

〔Effect of the invention〕

As explained above, unlike when using a ROM, programs and data can be modified and changed freely. It also makes it easy to fix bugs in the program. Also,
There is no need to distinguish differences in ROM specifications due to user specifications during manufacturing, and there is an advantage that they can be stocked. moreover,
For the user, there is no need to re-download the program because the program will not be rewritten even if there is an erroneous operation. There are many advantages to using RAM as ROM in this way.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the portable information device of the present invention, FIG. 2 is a circuit diagram showing a part of the control circuit 5B shown in FIG. 1, and FIG. 4 and 5 are circuit diagrams and memory maps showing one embodiment of the writing device used in the present invention, and FIG. 6 is a diagram showing another embodiment of the portable information device of the present invention. FIG. 7 is a block diagram showing an example of a conventional portable information device, and FIG. 8 is a detailed circuit diagram of a conventional control circuit 5B. 22. ・External equipment or more

Claims (1)

[Claims] In a portable information device equipped with a main power source and a sub power source, a CP
and a RAM which has a write control signal input terminal separated from the write control signal output terminal of the CPU and held at a write inhibit potential, and which is backed up by a battery by the sub power supply, and operates. During the process, the CPU is prohibited from writing data to the RAM, and the data in the RAM is stored by externally maintaining the write control signal input terminal at a write permission potential and loading data into the RAM from an external device. , a portable information device characterized by updating and correcting data.