JPH02141856A - Data bus converter in cpu board - Google Patents

Abstract

PURPOSE:To convert the data line of a microprocessor unit to a data line being suitable for an external bus by distinguishing 32, 16 and 8-bit data ports with an address. CONSTITUTION:A microprocessor unit has 32 pieces of addresses, therefore, constituted so that 32, 16 and 8-bit data ports can be distinguished with A31 and A30 of address lines. In a data bus converter 3, when a 32-bit data port signal 34 outputted from an address decoder 31 goes to logic '1', a bidirectional driver 32 to which it is connected becomes active, and data lines D0-D31 of the microprocessor unit 2 are connected to D0-D31 of external data buses through external data bus drive buffers 43-46. In the case of 16 bits, they are connected to D0-D15.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a computer system having a data bus for data transfer of a microprocessor and data transfer of an input/output device. The present invention relates to a device for performing

[Conventional technology]

32-bit microprocessor unit with dynamic bus sizing (e.g. MC68020)
The data transfer and size accrual input signals (DSACKO and DSAC
+ by determining the port size using
s, 16. Operands can be transferred to and from a 32-bit port.

(MC68020 User's Manual) When constructing a computer system, a standard data transfer method is usually used to connect a CPU board equipped with a microprocessor unit and an input/output board including a storage device.

For CPU boards equipped with a microprocessor unit with dynamic bus sizing function,
It is divided into 8-bit, 16-bit, and 32-bit data ports, and data is transferred using each method.

[Problem to be solved by the invention]

For example, in an embedded computer system as shown in Figure 3, a CPU board 1 that inputs and outputs through a standard data port.
, an input/output port door which is the same data port as the CPU board, and an input/output board 8.9 which is a data port different from the CPU board, accesses the input/output boards 8 and 9 which are data ports different from the CPU board. I can't do that. For example, CPU board 1 transfers data using a 32-bit port, and transfers data to an 8-bit port 9°16.
If an input/output board is connected to bit port 8 and 32-bit port 7, data can be transferred normally to the input/output port of the 32-bit port, but
If data is transferred to the input/output board of 16-bit port 8 or 8-bit port 9, an error will occur.

An object of the present invention is to provide an input/output board connected to a CPU board even if the data port is different from the microprocessor unit in the CPU board.

The purpose is to convert the data port within the CPU board to a data port suitable for the input/output board to which the data is transferred.

[Means to solve the problem]

In order to convert the data port into a data port suitable for the input/output board to which the data is transferred within the CPU board, as shown in FIG. , data bus converter 3
will be established. The data bus conversion device 3 sets a data port suitable for the input/output board based on the address used when accessing the input/output board, and performs data transfer.

Through the above, the purpose is achieved.

(Function) Figure 4 shows 3 with dynamic bus sizing function.
The correspondence with the data port of the external bus during longword data transfer of the 2-bit microprocessor unit is shown. When transferring to a 32-bit port, data lines D31 to DO of the processor are connected to data line D3 of the external bus.
1 to Do, and is performed in one bus cycle. 1
When transferring to a 6-bit port, data lines D31 to D16 of the processor are connected to data lines D15 to D of the external bus.
o, and two bus cycles are performed.

When transferring to an 8-bit port, data lines 031-D24 of the processor are connected to data lines D7-Do of the external bus.
The bus cycle is performed four times.

When constructing a computer system, if 32-bit data ports, 16-bit data ports, and 8-bit data ports are distinguished by address, the data bus conversion device can recognize each data port by decoding the address. . Thereby, the data bus conversion device is able to convert the data lines of the microprocessor unit into data lines suitable for the external bus.

The microprocessor unit has 32 data transfer destinations.
In order to identify whether the port is a bit data port, 16-bit data port, or 8-bit data port, the data transfer and size accrue signals of the dynamic bus sizing function are It looks like the picture. In the data bus conversion device, data transfer and size are determined by the data transfer end signal of the external bus.
Generates an acceleration signal and outputs it to the microprocessor unit.

As described above, long word data, word data, and 8-bit data can be transferred to input/output boards with 32-bit data ports, 16-bit data ports, and 8-bit data ports without malfunction.

〔Example〕

An embodiment of the present invention will be shown below. FIG. 3 shows an example of a built-in computer system. The built-in system includes a CPU board 1 for arithmetic control, an input/output port door ~9 including a main storage device, and a CPU board 1 and input/output port door ~9. 9
It consists of an external bus 5 that connects the The external bus was the VME bus, which is an international standard bus. An example of the configuration of the CPU board is shown in FIG. The CPU board 1 includes a 32-bit microprocessor unit 2 with a dynamic bus sizing function, a data bus conversion device 3, a driver 4 to an external bus 5, and a functional unit 6 within the CPU board.
It was composed of

FIG. 1 shows the configuration of a data bus conversion device.

The data bus converter 3 includes an address decoder 31 that decodes the address output by the microprocessor unit 2 and outputs a 32-bit data port signal 34, a 16-bit data port signal 35, and an 8-bit data port signal 36, and an address decoder 31 that decodes the address output from the microprocessor unit 2. It consists of a bidirectional driver 32 that connects the data line and drive buffers 43 to 46 to an external data bus, and a controller 33 that controls control signals between the microprocessor unit 2 and the external bus.

An example of the configuration of the address decoder 31 is shown in FIG. 6, and Marie is shown in FIG. 7. In this embodiment, the microprocessor unit has 32 addresses, so 32 bits, 1
The distinction between 6-bit and 8-bit data ports is made using the address line A31. Using the A30, it was possible to do this in units of 1 gigabyte.

For example, if A31 and A30 are both logic O, then contact 0 of switch 38 is followed. When contacts O of the switch 38 are both AB and OFF, the 32-bit data port signal outputs a signal level of H. A31 like this
The data port can be set using the signals A30 and the settings of the switch 38.

In the data bus conversion device 3, when the 32-pit data port signal 34 output from the address decoder 31 becomes logic 1, the bidirectional driver 32 to which it is connected becomes active, and the data line DO~ of the microprocessor unit 2 becomes active. D31 is connected to the external data bus Do-D31 via external data bus drive buffers 43-46. When the 16-bit data port signal 35 output by the address decoder 31 becomes logic 1, the bidirectional driver 32 to which it is connected becomes active, and the data lines D16 to D of the microprocessor unit 2 become active.
31 is connected to the external data bus Do-D 15 via external data bus drive buffers 43 and 44. Similarly, if the 8-bit data port signal 36 becomes logic 1,
Data line D23 of microprocessor unit 2
D31 is connected to Do-D7 of the external data bus.

The controller 33 transfers control signals, and
External bus data transfer end signal and address decoder 3
Analyzes the data port signal output by the microprocessor unit 1 and outputs a data transfer and size clearance signal to the microprocessor unit.

According to this embodiment, it is possible to match the data port of the microprocessor unit with the data port of the input/output board connected to the external bus.

The address decoder section of this embodiment uses A31 and A30 to distinguish between data ports, but the address to be decoded can be changed depending on the computer system. Also, although the data port was set by a switch, the data port can be determined by software.

In this embodiment, a 32-bit microprocessor unit is used, but any microprocessor unit with a dynamic bus sizing function can be used.

Any board that is equipped with a microprocessor unit that has a dynamic bus sizing function can use the data bus conversion device, and not only the CPU board but also any board that has masking rights among the boards connected to the external bus. It is effective for

〔Effect of the invention〕

According to the present invention, a data port of a microprocessor unit having a dynamic bus sizing function;
Since the data port of the input/output board connected to the external bus can be adapted to the data transfer destination, data can be transferred without being aware of the data transfer destination data bus. In other words, a 32-bit microprocessor unit can transfer 8-bit, 16-bit, or 32-bit data to an input/output board with an 8-bit or 16-bit data port.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of one embodiment of a data bus conversion device;
The figure shows a configuration diagram of an embodiment of a CPU board, Figure 3 shows a configuration diagram of an embedded computer system, and Figure 4 shows a data port correspondence table of an external bus when a 32-bit microprocessor unit performs long word transfer. Figure 5 shows MC68
FIG. 6 is a diagram showing the configuration of the address decoder of the embodiment, and FIG. 7 is a diagram showing the truth table of the address decoder of the embodiment. 3... Data bus conversion device, 31... Address decoder, 32... Bidirectional driver, 33... Controller, 34... 32-bit data port signal, 35
...16-bit data port signal, 36...8-bit data port signal, 43...Do-D7 buffer,
44...D8~D15 buffer, 45...D16~
Figure Figure 6 Figure 7

Claims (1)

[Claims] 1. In a computer system consisting of a microprocessor unit with a dynamic bus sizing function, a CPU board with an interface to connect to an external bus, and an input/output board including a storage device, the microprocessor unit A data bus conversion device for a CPU board, characterized in that data ports are selected according to addresses accessed by a processor unit, and matched with data ports of an input/output board connected to an external bus.