Bus control system

Abstract

A micro processor board of the bus control system comprises an internal bus which comprise a micro processor, address lines, data lines, and control signal lines, a memory connected via the internal bus with the micro processor, registers such as a system control register, and a bus interface circuit. The access to the main memory, the register, or the bus interface which is executed by the micro processor is outputted from an external bus via the bus interface circuit. Thus, the operation status of the micro processor or the internal bus can be traced by tracing the external bus.

Description

BACKGROUND OF THE INVENYION[0001] 1. Field of the Invention[0002] The present invention relates to a bus control system and particularly, to a bus control system applicable for bus trace for monitoring the operation status of a micro processor.[0003] 2. Description of the Prior Art[0004] There is disclosed a multi-chip module evaluating device in, for example, Japanese Patent Laid-Open No. 5-120160 (1993), which traces the wiring signal between a floating operation unit and a data memory. The wiring signal which is closed in the module substrate of a multi-chip module is traced by connecting, via a prober, a leader pad on the module substrate with a monitor unit which comprises a memory, an address generator, and a comparator. This evaluating device can trace directly the wiring signal, without using any test element group (TEG). Therefore, this evaluating device is employed for tracing the wiring signal, because an evaluation merely by signals extracted to external pins is not suff...

AI Technical Summary

Benefits of technology

[0012] Secondly, a high density mounting board such as a multi-chip module can be furthermore integrated in a higher density, keeping the compatibility of function of the internal bus tracing, because the exclusive pads becomes unnecessary and the wide mounting area is preserved.

Problems solved by technology

Therefore, this evaluating device is employed for tracing the wiring signal, because an evaluation merely by signals extracted to external pins is not sufficient, in case of mounting LSI packages on the module substrate.

Firstly, leader pads are necessary for tracing the wiring signal, because the wiring signal is closed in the module substrate. Accordingly, the above-mentioned evaluating device is not of any use for a multi-chip module which is small-size-oriented, because the number of pads increases with the increase in the number of wiring which completes in the module substrate, which results in the increase in pads area.

Secondly, a testing device is exclusively necessary for bus trace. Specially designed probers are required for connecting themselves with the special leader pads on the module substrate.

Thirdly, the reliability of bus trace is lowered. When the leader pads are inferior due to a manufacturing process, then the module substrate can not be traced completely.

Firstly, the leader pads become unnecessary for tracing the wiring signal which is closed in a module substrate, because every status of an internal bus can be traced via the bus interface.

Secondly, a high density mounting board such as a multi-chip module can be furthermore integrated in a higher density, keeping the compatibility of function of the internal bus tracing, because the exclusive pads becomes unnecessary and the wide mounting area is preserved.

Thirdly, bus trace becomes easy, because ordinary available instruments can be used for bus trace at the external bus connected with bus interface, or the peripheral circuit of a micro processor board.

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