JPH0119181B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to a microprogram-controlled data processing device. More specifically, the present invention relates to reducing the number of interface lines involved in controlling scan operations between functional units in a microprogram-controlled data processing system.

Prior Art The connection relationship between units in a conventional microprogram-controlled data processing device is outlined in the first section.
As shown in the figure.

In the figure, 110 to 11n are various units that operate under the control of the microprogram, and 100 is a unit that controls the execution of the microprogram. 120 is unit 100,1
This is a scan control unit that controls scan-in and scan-out operations for 10 to 11n. Unit 100 and Units 110-1
A microcommand line for transmitting microcommands is provided between 1n and 1n. This microinstruction line 130 is a collection of signal lines whose number is close to the number of bits of the microinstruction.

Scan control unit 120 and unit 10
A scan control line 140 dedicated to scan mode and a scan out data line 141 are provided between 0 and 110 to 11n. Scan control line 140
is a signal line that specifies scan operation (scan-in or scan-out), a word number that specifies the register to be scanned, a signal line that specifies the byte number and a bit number that indicates the target flip-flop in the byte, and a signal line that specifies the scan operation only. It consists of a group of signal lines for transmitting scan control information including trigger signals, scan operation instruction signals for each unit, and scan-in data (at the time of scan-in), and the number of signal lines is quite large.

In operation modes other than the scan operation, a microinstruction is issued from the unit 100 to the microinstruction line 130, and the operation of each unit 110 to 11n is controlled in accordance with this microinstruction.

On the other hand, in the scan operation mode, sending of microinstructions to the microinstruction line 130 is stopped. Each unit 100, 110 to 11n is connected to a scan control line 14 from a scan control unit 120.
A scan operation is executed according to scan control information sent through 0. In the case of scan-out operation, each unit 100, 110-11n transfers scan-out data to scan control unit 120 via scan-out data line 141.

As mentioned above, conventionally, the scan control line 14 was used as an interface line exclusively for scan operation.
0 and scan-out data lines 141 are provided between the units 100, 110-11n and the scan control unit 120. As mentioned above, the number of interface lines dedicated to these scan operations is quite large. This is unit 10
This is extremely disadvantageous in configuring 0,110 to 11n in a large-scale integrated circuit.

In other words, due to recent advances in integrated circuit technology,
Very large scale integrated circuits (VLSI) incorporating a huge number of logic elements are now being realized. By configuring the units 100, 110 to 11n using this VLSI, extremely large benefits can be obtained in terms of downsizing of the data processing device, etc. In this case, the number of VLSI input/output pins needs to be as small as possible in terms of physical size, price, etc.
It is desirable to reduce the number of interface wires of ~11n as much as possible. Of course, this is not limited to the case where VLSI is used, and it is generally desirable to reduce the number of interface lines as much as possible.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a microprogram-controlled data processing device in which the number of interface lines involved in scan operation control is reduced as much as possible.

General Description of the Invention The present invention has been achieved by focusing on the fact that the scan operation is a maintenance diagnosis mode and is in an exclusive relationship with the normal operation mode of a data processing device. That is, the microcommand line used for transmitting microcommands during the normal operation mode of the data processing device is used for transmitting scan control information and scan-out data during scan operation,
As an interface line dedicated to scan control,
Only a mode display line for controlling switching between the normal operation mode and the scan mode is provided between each unit and the scan control unit.

Embodiment of the Invention FIG. 2 is a connection diagram between each unit of the data processing apparatus according to the present invention.

200 is a unit that controls the execution of the microprogram, 210 to 21n are units under the control of the microprogram, and 220 is the unit 20.
This is a scan control unit that controls scan operations of 0,210 to 21n. A microcommand line similar to the conventional one is provided between unit 200 and units 210-21n. Two mode display lines 2 are used as interface lines dedicated to scan control.
40, 241 is the only scan control unit 220
It just comes out more. One mode display line 2
40 is connected to all of the units 200, 210 to 21n, but the other mode display line 241 is connected only to the microprogram execution control unit 200.

In the present invention, since the microinstruction line 230 is used to transmit scan control information and scanout data as described above, the microinstruction line 230
0 is also connected to scan control unit 220. That is, the microinstruction line 230 is routed from unit 200 to unit 210 in normal operating mode.
~21n, and in the scan operation mode, from the scan control unit 220 to each unit 200, 210~21n.
Serves as a multi-purpose bidirectional bus used to convey scan control information.

Since the operation in the normal operation mode is the same as the conventional one, the explanation will be omitted, and only the operation in the scan operation mode will be explained with reference to FIG.

Here, FIG. 3 shows the flow of processing in the scan control unit 220 from executing a scan operation from the normal operation mode to returning to the normal operation mode.

Process (a) is to stop the normal operation prior to starting the scan operation, and this process is a procedure that has been conventionally performed as a pre-process for scan control.

When the above preprocessing is completed, the scan control unit 220 sets the mode display line 241 to logic "1" (processing (b)). When the mode display line 241 becomes logic "1", the microprogram execution control unit 200 stops sending microinstructions to the microinstruction line 230 and releases the microinstruction line 230 for scan control information, as will be described later. do.

Next, proceed to processing (c), and scan control unit 2
20 also sets the other mode indicator line 240 to logic "1". When this mode display line 240 becomes logic "1", each unit 200, 210
~21n switches to scan mode, recognizes the information on the microcommand line 230 as scan control information, and imports it internally.

Thereafter, the scan control unit 220 transmits scan control information as described above to the microinstruction line 2.
30 (processing (d)). 20 units each
0, 210 to 21n execute scan operations according to scan control information sent through the microcommand line 230. If this scan operation is a scan-in operation, the scan-in data included in the scan control information is scanned in, but if it is a scan-out operation, the scan-out data is output onto the microinstruction line 230 and transferred to the scan control unit 220. do. The scan operation within each unit may be the same as in the prior art, and the content of the scan control information may also be the same as in the prior art, so detailed explanations regarding these will be omitted.

After completing the necessary scan operation, the scan control unit 220 sequentially executes processes (e), (f), and (g). These processes are the reverse operations of processes (a), (b), and (c), and their contents are as shown in FIG. This causes the unit 200 to
to be used for microinstructions again and return to normal operating mode. Similarly, the units 210 to 21n return to their normal operation mode and begin to recognize the information on the microinstruction line 230 as microinstructions and take them in.

Microprogram execution control unit 200
An example of a circuit related to switching control of the microinstruction line 230 will be explained with reference to the block diagram of FIG.

In FIG. 4, 231 to 23n are signal lines constituting a micro command line (multipurpose bidirectional bus) 230, 431 to 43m are signal lines constituting an internal bus of the unit 200, and 43n carries skinout data. This is an internal signal line. 401~
40n is a flip-flop that constitutes a microinstruction read register, and 411 to 41n are input terminals.
This is a driver circuit with an AND function. 421～
42n is an AND circuit, and 440 is a NOT circuit.

In normal operating mode mode indicator lines 240,2
41 are all reset to logic "0". Therefore, the output of NOT circuit 440 is logic "1", and driver circuits 411-41n send the contents of flip-flops 401-40n, ie, microinstructions, to microinstruction lines 231-23n. AND circuits 421-42n are all inhibited, and microinstruction lines 231-23n and signal lines 431-43n are separated.

When the mode display line 241 becomes logic “1”,
The output of the NOT circuit 440 becomes logic "0" and the driver circuits 411 to 41n switch to the flip-flop 4.
01 to 40n and microinstruction lines 231 to 23n are separated. Then, when the mode display line 240 becomes logic "1", the AND circuits 421 to 42n are opened. Therefore, the scan control information carried from the scan control unit 220 to the microcommand lines 231 to 23n is transferred to the internal bus signal lines 431 to 43m.
be taken in. Also, in scan-out operation,
Scan out data is from internal signal line 43n
Micro instruction line 23n via AND circuit 42n
sent to.

Effects of the Invention As detailed above, by using the microcommand line, which is not used in scan mode, to transmit scan control information and scan out data in scan mode, it is possible to Only a mode display line is provided. However, since approximately 10 to 20 signal lines are normally required to transmit scan control information and scan-out data, the present invention significantly reduces the number of interface lines for each unit of a data processing device. be able to.

[Brief explanation of drawings]

Fig. 1 is a connection diagram between units in a conventional data processing device, Fig. 2 is a connection diagram between units in a data processing device according to the present invention, and Fig. 3 schematically shows the processing flow of the scan control device. FIG. 4 is a block diagram showing an example of a circuit related to microinstruction line switching control within the microprogram execution control unit. 200...Unit that controls the execution of the microprogram, 210-21n...Unit under the control of the microprogram, 220...Scan control unit, 230, 231-23n...Micro command line, 240, 241...Mode Display line.

Claims (1)

[Claims] 1. In a microprogram-controlled data processing device comprising a plurality of functional units interconnected by an interface line including at least a microcommand line for transmitting microcommands, the microcommand line and the mode display line Therefore, a scan control unit is provided which is connected to each of the functional units, and when the scan control unit displays a scan mode on the mode display line and sends scan control information to the micro-command line, each of the functional units It operates in scan mode and executes a scan operation according to scan control information on the microcommand line, and when the scan operation is a scanout operation, sends scanout data to the scan control unit via the microcommand line. A data processing device comprising: