JPS594337Y2 - Program automatic switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for switching from a system program to a maintenance program such as debugging in a computer system, particularly a microcomputer system.

Generally, in a microcomputer system, the system program is corrupted due to some accident, or
When a system program is changed, it is necessary to debug it. In such cases, a teletypewriter (rTTY) is connected and debugging is performed using a monitor program resident in the ROM. .

In the above case, conventionally, when the CPU board is powered on, initial values of each input/output device, etc. are set as an initial process.

At this time, the system program start switch provided on the CPU board is opened, and the monitor program start switch is turned on manually to perform debugging. Decreased work efficiency due to forgetting to put in the product, etc., was a problem.

The present invention was made to solve the above problem, and focused on the fact that a TTY is always used to operate a monitor program, so that the program is automatically started by connecting a TTY. The present invention provides an automatic program switching device for a computer system characterized by:

The present invention will be explained in detail with reference to Examples below.

In addition, in all figures, parts having equivalent functions are given the same symbols.

FIG. 1 shows the block constituent countries of one embodiment of the present invention.

In the figure, 1 is the CPU board of the microcomputer;
2 is a ROM in which a monitor program resides.

3 is RAM, 4 is TTY interface, 5 is TTY
connector, 6 is an address bus, 7 is a data bus, 8 is a control signal line, 9 is a 3-state gate circuit arranged in the TTY interface 4, and the TTY connection flag signal from the TTY connector 5 and the TTY interface 4
It outputs when the flag sense signal port from the instruction decoding circuit 10 disposed inside is input (see FIG. 3).

The instruction decode circuit 10 is a circuit that generates instruction signals such as flag sense signal ports determined by the CPU board 1.

GND indicates grounding.

FIG. 2 shows the detailed configuration of the TTY connector 5 shown in FIG. 1, and 5a is a TTY connector member on the TTY interface side, which includes a TTY connection detection terminal 11a and a GND terminal 11b.

5b is a TTY connector member on the TTY side;
It is provided with terminals 11a' and 11b' corresponding to the Y-connection detection terminal 11a and the GND terminal 11b.

Reference numeral 12 denotes a pull-up resistor, which is connected between the power supply (+5 V) and the TTY connection detection terminal 11a.

13 is a jumper wire, which connects the terminals 11a' and 11b'
A conductor that connects the TTY when the TTY is connected.
This is for grounding the potential of the terminal on the TY interface side.

FIG. 3 is a signal waveform diagram for explaining the operation of the three-state gate circuit 9. Figure a is a signal waveform diagram of each terminal when TTY is not connected, and diagram b is a diagram of signal waveforms at each terminal when TTY is connected. It is a signal waveform diagram of each terminal.

In the figure, A and A' are TT from TTY connector 5.
Y connection flag signal, 口 is a flag sense signal from the instruction decoding circuit 10, C and 8' are 3-state gate circuit 9
This is the output signal of

Next, the operation of this embodiment will be explained.

(1) Operation when no TTY is connected When the power of the CPU board 1 is turned on, initial values of each input/output device (not shown), etc. are set as an initial process.

Thereafter, flag sensing is performed to determine whether or not the TTY is connected.

At this time, since the TTY is not connected, the TTY connection flag signal A and the flag sense signal port shown in FIG. 3A are input to the three-state gate circuit 9, and its output is
” level becomes the “0” signal.

The result of sensing the flag in response to this output signal is "NO", and the program is directly branched to the system program, which is then executed.

(2) Operation when TTY is connected The operation until flag sensing is performed is the same as in case (1), but when this flag sensing is performed, since TTY is connected, 3 steps are performed. The TTY connection flag signal iso-lag sense signal port shown in FIG. 3 is input to the gate circuit 9, and its output becomes a signal of "1" at the "H" level.

The result of flag sensing is rYES due to this output signal.
, which is branched into a monitor program, and this monitor program is executed.

FIG. 4 shows the above operation in a flowchart.

As explained above, according to the present invention, the start of the monitor program is automatically switched just by connecting the TTY. You won't forget anything, and your work efficiency will be further improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a detailed diagram of the TTY connector 5 shown in FIG.
FIG. 4 is a signal waveform diagram for explaining the operation of the three-state gate circuit 9 shown in the figure, and FIG. 4 is a flowchart of the operation of this embodiment. 1...Microcomputer CPU board, 2
...ROM, 3...RAM, 4...
...TTY interface, 5...TTY
Connector, 5a, 5b... TTY connector member, 6... Address bus, 7... Data bus, 8... Control signal line, 9... . . . 3-state gate circuit, 10 . . . Instruction decode circuit, 11a. il b, 11 a', 11 b'...-TT
Y connection detection terminal, 12・----・Pull-up resistor, 1
3...Jumper wire.

Claims (1)

[Scope of utility model registration request] In a computer system in which a maintenance program is built into a CPU board, a teletypewriter connection detection terminal and a ground terminal having a potential are arranged on the CPU board,
The present invention further includes means for grounding the potential of the teletypewriter connection detection terminal when a teletypewriter is connected to the CPU board, and means for automatically switching activation of the maintenance program depending on whether or not the teletypewriter is connected. Features an automatic program switching device.