US 6,209,049 B1Granted

Data processing system and method for inputting data from storage devices where the data buss width for input depends on the number of memory devices

AssigneeBrother Kogyo Kabushiki Kaisha

InventorHajime Usami

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Abstract

A data processing system and a method for inputting data from storage devices provided in the data processing system, in which the ROM address areas in a memory map include an area for reading in a 32-bit bus mode and an area for reading in a 16-bit mode, which areas are set so that a portion of the addresses are equal. When a 32-bit data read is performed for the area used to read in 32-bit bus mode and the high-order 16 bits are invalid, it is determined that only one ROM device is mounted in the system. Therefore, accesses are performed with the area used to read in 16-bit bus mode. After determining the number of ROM devices in this way, the result is written to a mode register. The selector reads this result stored in the mode register and, when only one ROM device is mounted in the system, supplies Address A1 to the highest-order address terminal RA17 of the ROM device.

Claims18

Dependent claims

A data processing system comprising:

a data processing unit that switches a process data input mode for each prescribed area in a total address space between a first mode, in which data is input at a first number of bits, and a second mode, in which data is input at the first number of bits by performing a plurality of inputs at a second number of bits smaller than the first number of bits;
at least one storage device, each storage device outputting process data at the second number of bits;
and
an address data converter that converts address data for the at least one storage device,
wherein the data processing unit comprises:
address data output means for outputting address data for selecting an external device having a prescribed area allocated in the total address space;
storage device number determination means for determining number of storage devices and outputting results of determination;
and process data input means for inputting process data from the at least one storage device, using either a first address area by the first mode or a second address area by the second mode, based on the results of determination,
wherein the address data converter comprises:
address data extraction means for extracting address data and outputting the address data to the at least one storage device based on whether the address data from the data processing unit corresponds to the first address area or the second address area so that the process data is output from the at least one storage device either on the first number of bits basis or the second number of bits basis;
and selecting means for outputting signals based on the address data to select the at least one storage device, and
wherein the at least one storage device is connected to at least one connection device that connects to the address data extraction means via an address data line and the data processing unit via a process data line.

9 more elements

A method for inputting data from storage devices in a data processing system, wherein the data processing system includes a data processing unit for switching a process data input mode for each prescribed area in a total address space between a first mode, in which data is input at a first number of bits, and a second mode, in which data is input at the first number of bits by performing a plurality of inputs at a second number of bits smaller than the first number of bits;

storage devices for outputting process data at the second number of bits;
and an address data converter for converting address data for the storage devices, the method comprising:
an outputting process for outputting address data to select external devices each having a prescribed address area allocated in the total address space;
a determining process for determining the number of storage devices;
an inputting process for inputting process data from the storage devices, using either a first address area by the first mode or a second address area by the second mode, based on the results of the determining process;
an address data extraction and outputting process for extracting necessary address data and outputting the necessary data to the storage devices based on whether the address data from the data processing device corresponds to the first address area or the second address area so that the process data is output from the storage devices either on the first number of bits basis or the second number of bits basis;
and
a selecting process for outputting signals selecting the storage device based on the address data.

5 more elements

Dependencies are inferred from the claim text.