Electrical computers and digital data processing systems: input/ – Input/output data processing – Peripheral configuration
Reexamination Certificate
1999-08-18
2003-12-02
Lee, Thomas (Department: 2185)
Electrical computers and digital data processing systems: input/
Input/output data processing
Peripheral configuration
C710S019000, C710S301000
Reexamination Certificate
active
06658497
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a method whereby a processing unit, which is connected through a common data bus to a plurality of devices for controlling these devices or for performing control operations through the use of these devices, recognizes connection states of the devices, and further to a processing unit having a device connection state recognizing function, to which this method is applied.
2) Description of the Related Art
FIG. 28
is a block diagram showing an example of configuration of a system in which a plurality of devices are connected to a general processing unit. In
FIG. 28
, a processing unit
100
is in connection with a plurality of devices, such as an LCD (Liquid Crystal Display)
121
, a RAM
122
and a ROM
123
. The connection between these LCD
121
, RAM
122
and ROM
123
, and the processing unit
100
is made through a common 8-bit data bus
110
comprising data signal lines DT
0
to DT
7
, and, additionally, the LCD
121
, the RAM
122
and ROM
123
are connected to the processing unit
100
through signal lines
111
a
,
111
b
,
111
c
for the interchange of address signals, control signals and others, respectively.
Furthermore, the processing unit
100
supplies a display control signal through the signal line
111
a
to the LCD
121
, and sends display data through the data bus
110
to the LCD
121
, thereby executing the display control on the LCD
121
. Still further, the processing unit
100
sends address signal or a write/readout instruction signal through the signal line
111
b
to the RAM
122
to thereby control the data write into the RAM
122
or the data readout from the RAM
122
. Moreover, the processing unit
100
forwards an address signal or a readout instruction signal through the signal line
111
c
to the ROM
123
to thereby control the data readout from the ROM
123
.
Meanwhile, a system, shown in
FIG. 29
, is equivalent to the removal of the ROM
123
from the system shown in
FIG. 28
, and is in connection with an LCD
121
and a RAM
122
which form devices.
While the difference between the system shown in FIG.
28
and the system shown in
FIG. 29
is the device connection state to the processing unit
100
, usually the processing unit
100
does not have a means to detect and recognize such a device connection state difference (that is, the devices connected to the processing unit
100
).
Thus, it would be considered that signal lines dedicated to detection are provided so that the processing unit
100
bears a means for detecting the presence or absence of the devices.
However, in the case of the method of recognizing a device connection state with the installation of the signal lines dedicated to detection, if the number of devices to be connected to a processing unit increases, the number of signal lines dedicated to detection increases accordingly, and if, for example, the processing unit is an integrated circuit, the increase in the number of signal lines on a chip requires high density wiring of the signal lines, which leads to a rise of cost. For this reason, a desire exist that the device connection state can be recognized without the addition of the signal lines dedicated to detection.
Meanwhile, a computer system for use in various kinds of application is equipped with a plurality of devices according to these applications, with these devices being placed under control of a processing unit (control integrated circuit or the like). In such a system, in order to control various types of devices, a ROM previously retains drivers/handles (device control programs) to devices connected, and a CPU constituting the processing unit reads out and starts the drivers/handlers from the ROM at the starting of the system.
For instance, as
FIG. 30A
shows, a hardware
200
, bearing four devices D
1
, D
3
, D
4
and D
8
, previously contains a ROM
210
retaining four drivers/handlers (device control programs) for taking charge of control of these devices D
1
, D
3
, D
4
and D
8
. In this case, at the starting of the system, a CPU in the hardware, as shown in
FIG. 30B
, successively reads out the drivers/handlers for the four devices D
1
, D
3
, D
4
and D
8
from the ROM
210
and starts them (see steps A
11
to A
14
).
Furthermore, as
FIG. 31A
shows, a hardware
201
, being equipped with six devices D
1
, D
2
, D
3
, D
4
, D
7
and D
8
, internally has a ROM
211
previously retaining six drivers/handlers (device control programs) for controlling these devices D
1
to D
4
, D
7
and D
8
. In this instance, as shown in
FIG. 31B
, at the starting of the system, a CPU in the hardware
201
successively reads out the drivers/handlers for the six devices D
1
to D
4
, D
7
and D
8
from the ROM
211
to start them (see steps A
21
to A
26
).
In like manner, as
FIG. 32A
shows, a hardware
202
, including two devices D
7
and D
10
, contains a ROM
212
previously storing two drivers/handlers (device control programs) for controlling these devices D
7
and D
10
. In this case, as shown in
FIG. 32B
, at the activation of the system, a CPU in the hardware
202
successively reads out the drivers/handlers for the two devices D
7
and D
10
from the ROM
212
to activate them (see steps A
31
, A
32
).
In case where each computer system employs a different connection state of devices as noted above, there is a need to prepare a ROM conforming to the devices of each computer system.
In general, the devices to be connected to various types of computer systems are not always different from each other at every service, but are common thereto in many cases. For instance, the different devices are limited to some types such as a keyboard, a printer, an IC (Integrated Circuit) card in addition to the LCD, the RAM and the ROM mentioned above. That is, some are selected from these devices and connected thereto.
Thus, it would be considered to prepare a general-purpose ROM previously storing drivers/handlers for all devices which may be connected to computer systems and to, at the activation of a system, recognize the devices connected to that system so that the drivers/handlers (device control programs) for the devices recognized are read out from the general-purpose ROM and put to activation. For instance, as far as the examples shown in
FIGS. 30
to
32
is, the general-purpose ROM to be provided is one storing all the drivers/handlers (device control programs) for the devices D
1
to D
10
. This can eliminate the need for preparing a different ROM for each computer system, which saves troubles to be taken in storing programs in the ROM and simplifies the management of parts, thereby contributing to the reduction of system manufacturing cost.
However, in the conventional ways, since the processing unit does not have a means to recognize the devices connected thereto as mentioned above, irrespective of the employment of a versatile ROM, difficulty is experienced in reading out only the required drivers/handlers (device control programs) for their start.
In addition, if signal lines dedicated to detection for recognizing the device connection states are provided in order to make the general-purpose ROM available, as mentioned before, this results in the increase/higher density in the signal lines on a chip, and in its turn leads to higher cost. Accordingly, a stronger desire exists that the recognition of the device connection state is feasible with no additional signal lines dedicated to detection.
SUMMARY OF THE INVENTION
The present invention has been developed in consideration of this situation, and it is therefore an object of this invention to provide a device connection state recognizing method and a processing unit having a device connection state recognizing function, which are capable of recognizing the device connection state without adding signal lines dedicated to detection.
For this purpose, in accordance with this invention, there is provided a device connection state recognizing method by which a processing unit exhibiting an ability to have connection th
Hashimoto Shigeru
Kawasaki Yusuke
Yamamoto Koken
Armstrong Westerman & Hattori, LLP.
Cao Chun
Fujitsu Limited
Lee Thomas
LandOfFree
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