JPS63113652A - I/o device - Google Patents

Abstract

PURPOSE:To perform initialization at a high speed without using the CPU in a main body, etc., by placing an I/O port in a specific state according to I/O port control information from a storage means when the power source is turned on. CONSTITUTION:A control circuit 6 controls a ROM 1 after being powered on to output data stored in the ROM 1 to a two-way bus 4, and presets and resets a register 2 for control through the two-way bus 4. Thus, the initialization is carried out. The transmission timing of the data in the ROM 1 is based upon, for example, a sequence when the initialization based upon a program is performed by a CPU. Thus, the CPU is released from the sequential program execution for the initialization. Consequently, the sequence of the whole system is simplified and the burden on an I/O device user is lightened.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an Ilo (Input Loud Memory) system that performs initial settings using a ROM (mask ROM, EPROM, etc.).
ut) device.

[Conventional technology]

Conventionally, this type of I10 device operated by maintaining a certain state after power-on and waiting for the next command from the CPU.

[Problem that the invention seeks to solve]

Therefore, the only way to obtain an arbitrary operating mode (this will be referred to as initial setting) is through instructions based on a program from the CPU. Therefore, the initial setting (
For example, to specify the direction of human output or to specify an interrupt request, the CPU uses Fetch-Ex
ecute operation, which complicates the sequence of the entire system.

An object of the present invention is to provide an I10 device that solves the above problems.

(Means for Solving Problems) The present invention includes an I/O port, a storage means that stores control information for controlling the I/O port, and an I/O and means for setting the port to a predetermined state.

[Effect]

According to the present invention, when the power is turned on, the I/O port is set to a predetermined state based on the I/O port control information from the storage means.

(Example) FIG. 1 shows an embodiment of the invention.

1 is a ROM used during initial settings, and 3 is an I/O port. Reference numeral 2 denotes a control register for controlling various operation modes of the I/O port 3, which is directly preset and reset by data stored in the ROMI. 4 is the CPU (for example inside the computer), register 2 and I
A bidirectional bus 5 connects the /O port, and a data bus 5 connects the external interface and the I10 port 3.

According to the above configuration, after the power is turned on, the control register 2 is directly preset/reset using the data stored in the ROMI. Initial settings are performed by this.

FIG. 2 shows another embodiment of the invention.

1 is the ROM used during initial settings, 3 is the I/O port,
2 is a control register for controlling various operation modes of the I/O port, 4 is a bidirectional bus that connects the CPU with register 2 and I/O port 3, and 5 is an external interface and I/O port 3. 6 is R
This is a control circuit for controlling OMI.

Output data from ROMI is output to bidirectional bus 4.

According to the above configuration, after power is turned on, the control circuit 6 controls the ROMI, outputs the data stored in the RO1 to the bidirectional bus 4, and outputs the data stored in the bidirectional bus 4 to the control register. Preset/reset 2. Initial settings are performed in this way. Note that the data transmission timing in the ROMI conforms to a series of sequences when performing initial settings based on a program by the CPU, for example.

As described above, the CPU is freed from executing a series of programs for initialization. Therefore, the sequence of the entire system can be simplified. This is I1
0 This will reduce the burden on device users.

Furthermore, the CPU can use the time required for initialization for other processing. Since the initial setting program is performed by ROMI, the initial setting can be processed at high speed. By making the ROMI a mask ROM or EPROM, the data stored in the RO can be changed as necessary, making the I10 device more versatile.

According to the configuration shown in Figure 1, since the flip-flops constituting the control register 2 of the I/O port are directly set and reset by the contents of ROMI, the execution time is shorter than when the CPU performs initial settings using a program. can be reduced.

(Effects of the Invention) As explained above, according to the present invention, the CPU inside the main body, etc.
Initial settings can be performed quickly without using .

[Brief explanation of the drawing]

Figure S1 is a block diagram showing an embodiment of the present invention; FIG. 2 is a block diagram showing another embodiment of the invention. 1...ll0M. 2...control register, 3. Tsukasa 70 port, 4...Two-way bus, 5...data bus, 6...Control circuit.

Claims (1)

[Claims] an I/O port, a storage means for storing control information for controlling the I/O port, and means for setting the I/O port to a predetermined state based on the information stored in the storage means when power is turned on. An I/O device characterized by comprising: