JPH06314359A - Ic memory card - Google Patents

Abstract

PURPOSE:To provide an inexpensive IC memory card capable of sufficiently utilizing the throughput of a CPU by constituting an IC memory card of an IC mounted with a high-speed access memory, a low-speed access memory and a memory control circuit. CONSTITUTION:An IC memory card 5 which includes a memory control circuit 2 connected to a high-speed access memory 3 and a low-speed access memory 4 transfers data to a CPU 6 via a system bus 1. When the data or the access requests transferred from the CPU 6 at a superhigh speed have the sequential accesses to a memory at a high speed, the memory 4 can deal with such a case via the circuit 2 as long as the data are previously latched since the next access address is known. Meanwhile the circuit 2 decides the types of data and distributes the data to both memories 3 and 4 so that a random access is given to the area of the memory 3 when this memory 3 is available.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC memory card.

[0002]

2. Description of the Related Art A conventional IC memory card is used in various computer devices as a simple storage device having excellent portability. The IC memory card is a read-only RO
An auxiliary storage medium that is configured by M and has a program that is repeatedly executed or data that is read is written and a RAM that is backed up by a battery to allow reading and writing and holding the contents. There is something used as.

Most of the ROMs used for ICs are electrically erasable programmable ROMs (hereinafter referred to as EEPROMs) and electrically rewritable PROMs (hereinafter referred to as EAROMs) such as flash memories (for example, FEEPROMs). In the case of RAM, ECLRAM that saves power and enables ultra-high-speed access
Etc. static RAM (hereinafter referred to as SRAM) is used.

A memory having a low-speed access cycle is used as the auxiliary storage medium, and the accessing CPU accesses the system bus at high speed, whereas the storage medium side slows down the throughput of the entire system. Therefore, the IC memory card, which is composed of a power-saving ultra-high-speed SRAM and has a memory backed up by a battery, has high performance.

In fact, the IC memory card uses a semiconductor memory element which requires very little time for access, as compared with a general memory medium such as a magnetic disk which requires a mechanical operation, and is compact. It is regarded as a promising device that constitutes a computer system because accidents during access are unlikely to occur.

[0006]

As described above, the conventional IC memory card is a storage medium that can be accessed at high speed and is excellent in stability and performance. However, ultra-high-speed SRAMs and ROMs such as ECLRAM are quite expensive as a whole, so it is difficult to reduce the cost of the IC memory card. Although it has the advantages of shorter access time and stable operation than storage media such as magnetic disks that are widely used, it can be said that the IC memory card is prevented from becoming more popular due to cost problems. .

Although it is possible to reduce the cost of the IC memory card by mounting a normal inexpensive SRAM, the access cycle becomes long. If a computer system is configured using an IC memory card that uses a memory with a long access cycle, it is not possible to make use of the high processing capacity of the CPU, which has gradually improved its performance and has become a considerably high function.

An object of the present invention is to provide a low-cost IC memory card which can utilize the processing capacity of a CPU to be connected.

[0009]

In order to solve the above problems, an IC memory card of the present invention has at least a low speed access memory and an IC equipped with a memory control circuit for controlling reading and writing of the low speed access memory. And Further, a high-speed access memory can be similarly connected to the present memory control circuit, and may be configured by an IC having a high-speed access memory, a low-speed access memory, and a memory control circuit. By accessing the IC memory card via the internal memory control circuit,
High-speed access to high-performance CPU etc. is possible, and cost is reduced.

The memory control circuit is provided with a data latch that can be accessed at high speed from the system bus side. As a result, an inexpensive low-speed access memory can be applied to a memory area in which addresses to be accessed by the CPU are sequentially determined, such as a memory area to be sequentially accessed. Further, in the case of having a high-speed access memory, it is possible to provide a memory area that is randomly accessed at high speed in a part and have a suitable configuration depending on the usage state of the memory.

Access to the slow access memory is
By pre-reading by the data latch provided in the memory control circuit, the throughput does not decrease.

[0012]

Embodiments of the present invention will be described with reference to the drawings. Figure 1
FIG. 3 is an explanatory diagram showing an embodiment of an IC memory card of the present invention. In the illustrated embodiment, an IC memory card 5 of the present invention, in which one high-speed access memory 3 and one low-speed access memory 4 are connected to one memory control circuit 2, a system bus 1
An example of exchanging data with the CPU 6 via the is described. In the drawings, the system bus and the memory control circuit, and the memory control circuit and the bus width for inputting and outputting in each memory are not taken into consideration, but of course, the input / output bus between the low-speed access memory and the memory control circuit is the system. It is smaller than the bus width of the bus.

When data or access requests transferred from the CPU at an extremely high speed are sequentially accessed at high speed to the memory, the next access address is known. Therefore, if the data is latched in advance, the memory control circuit Can be handled by a low-speed access memory. In the case where the high-speed access memory is provided, the memory control circuit determines the data type and the like so that the area of the high-speed access memory is randomly accessed, and divides the data into the high-speed access memory and the low-speed access memory.

[0014]

As described above, according to the IC memory card of the present invention, the cost can be suppressed by using only the low speed access memory when only the sequential access is performed. Further, the memory of the IC memory card is divided into a randomly accessed area and a sequentially accessed area. A high-speed access memory is used for a randomly accessed area, and a low-speed access memory is used for a sequentially accessed area, so that the memory control circuit can access each memory. Therefore, even in this case, IC
The access time can be shortened as a memory card, and the cost can be suppressed because an inexpensive low-speed access memory is used in the sequential access memory area.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of an IC memory card of the present invention.

[Explanation of symbols]

 1 System Bus 2 Memory Control Circuit 3 High Speed Access Memory 4 Low Speed Access Memory 5 IC Memory Card 6 CPU

Claims (2)

[Claims] 1. An IC memory card, which comprises a memory control circuit connected to a system bus to control a data latch and a data bus in the IC memory card, and a low-speed sequential access memory connected to the memory control circuit. IC memory card. 2. In an IC memory card, a memory control circuit which is connected to a system bus and performs data latch and data bus control in the IC memory card, a low-speed sequential access memory connected to the memory control circuit, and a memory control circuit An IC memory card characterized by comprising a high speed random access memory.