JPS6261976B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field to which the invention pertains] The present invention relates to a code conversion method in an information processing system. [Prior Art] In an information processing system in which a central processing unit, a storage device, and an input/output control device are connected via a bus,
Code of information input/output by input/output control device,
When the codes of information processed by the central processing unit are different, code conversion becomes necessary. Conventionally, code conversion methods for this type of information processing system include a method in which code conversion of input/output information is performed on the storage device using software in the central processing unit; a method in which code conversion hardware is added to the storage device; There is a method in which code conversion is performed by hardware on the storage device according to instructions from software for input/output information buffers allocated on the storage device for transfer.A method in which code conversion is performed within the input/output control device. . Since code conversion is performed by software in the above method, if the amount of input/output information to be code converted is large, the overhead of the software increases and the burden on the software increases. This method has the disadvantage that if there are a large number of input/output control devices that require code conversion, the management of the input/output information buffer by software becomes redundant, which increases the burden on the software. In this method, code conversion hardware or a control program must be provided in each input/output control device, which has the disadvantage that the amount of hardware for each input/output control device increases or the control program becomes complicated. It was hot. That is, the conventional methods have disadvantages in that the burden on software is large, the amount of hardware is large, or the control program is complicated. [Object of the Invention] The object of the present invention is to develop a shared code that converts information in information transfer via a bus between input/output control units, central processing units, storage devices, and other bus-connected devices connected to the bus. A conversion device is connected to the bus, and the transfer information on the bus is taken into the code conversion device by intervening in the information transfer bus cycle between the devices that require code conversion, and after performing the code conversion, in place of the transfer information. By sending the code-converted information to the destination device, the code conversion device makes it appear as if the code conversion is being performed on the bus, which eliminates the above-mentioned drawbacks, reduces the burden on software, or reduces the burden on individual input/output devices. It is an object of the present invention to provide a code conversion system that can reduce the hardware of a control device or simplify the control program. [Structure of the Invention] According to the present invention, two or more devices that are connected to a bus and exchange information via the bus, and a signal or bus connection device that is connected to the bus and instructs code conversion are specified. In response to the signal, (1) means for inputting transfer information on the bus; (2) means for permitting or prohibiting a bus connection device from inputting transfer information from the bus or outputting information to the bus; ) a code converting device comprising means for code converting input transfer information and outputting the code converted information to the bus, the transfer information on the bus to the code converting device regarding the information transfer bus cycle of the bus; A code conversion method is obtained which is characterized in that after inputting and converting the code, the code-converted information is sent to the transfer destination bus connection device instead of the transfer information. [Description of Embodiments] Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and the portion surrounded by the dashed line in the figure shows the portion related to the code conversion method according to the present invention. The bus B in the embodiment shown in FIG. 1 is a bidirectional bus, which includes a data bus DB and an address bus AB that transfers the device address of the other device to which the transfer is to be performed.
and a bus control line CB that passes signals that control writing data to and reading data from the partner device, and signals that control code conversion operations. Central processing unit CPU, input/output control unit
The IOC and the storage device MEM are connected to the data bus DB of the bus B, the address bus AB, and the bus control line CB, respectively, and the code conversion device COD is connected to the data bus DB of the bus B and the bus control line CB. This embodiment has the configuration surrounded by the above-mentioned dashed line, but in addition to this, as shown in numbers 1 to 4 in Table 1, there are a pair of bus connection devices that can communicate with each other via bus B, and a code conversion device COD. It is also possible to realize a code conversion method using a combination of the following. In addition, Table 1
An example in which a code conversion device is added to the pair numbered 5 corresponds to the embodiment shown in the dashed line in FIG. Next, the basic operating principle of bus B shown in FIG. 1 will be explained. Although the details of the transfer format of bus B are omitted, the transfer between each device is roughly performed as follows.

〔Effect of the invention〕

As explained above, the present invention captures the transfer information flowing on the bus with a code conversion device shared by the system as necessary, converts the code, and then sends it to the transfer destination device. This has the effect of reducing the burden on the software and reducing hardware code conversion.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a block diagram showing details of each device and bus shown in FIG. 1, and FIG. 3 is an operation timing diagram of the block diagram shown in FIG. 2. B...Bus, DB...
…data bus, AB…address bus, CB…bus control line, IOC…input/output control device, COD…
Code converter, MEM...Storage device, C1...
Bus request signal, C2...Bus cycle signal, C3
...Write instruction signal, C4...Read instruction signal,
C5... Code conversion instruction signal, C6... Code conversion execution signal, 1, 3, 4, 9, 15, 16... Tri-state gate, 2, 18... AND gate, 5, 10, 13... Control circuit , 6...Address register, 7...Data transmission/reception register, 8...
...Inverter, 11...Data latch register,
12...Code conversion circuit, 14...Address comparison circuit, 17...Memory, S1...Output enable signal, S2...Input enable signal, S3...Address match signal, S4...Read enable signal, S5... Write enable signal.

Claims (1)

[Claims] 1. Two or more devices that are connected to a bus and exchange information via the bus, and a signal that is connected to the bus and instructs code conversion or a signal that specifies a bus-connected device. In response, (1) means for inputting transfer information on the bus; (2) means for permitting or prohibiting a bus connection device from inputting transfer information from the bus or outputting information to the bus; and (3) inputting. a code converting device comprising means for code converting the transferred information and outputting the code converted information to the bus, and inputting the transfer information on the bus to the code converting device regarding the information transfer bus cycle of the bus. A code conversion method characterized in that after code conversion, code-converted information is sent to a transfer destination bus connection device instead of the transfer information.