Device for detecting whether an attached external memory stores valid data, if not, whether the external memory is capable of storing data

Claim 2

A data processing device adapted to attachably and detachably couple with an external memory unit to which data are written and from which data are read, said external memory unit storing data even when not coupled to said data processing device, said data processing device comprising: discriminating means for determining whether said external memory unit is coupled to said data processing device; judging means for judging if a predetermined kind of data are stored in said external memory unit when said discriminating means determines that said external memory unit is coupled to said data processing device; another judging means for judging if said predetermined kind of data stored in said external memory unit are usable when said judging means judges that said predetermined kind of data are stored in said external memory unit, said another judging means including means for performing a sum check on said predetermined data and comparing said sum check result with a sum result stored in said external memory unit; error indicating means for indicating that said predetermined kind of data are not usable when said another judging means judges that said predetermined kind of data are not usable; and, third judging means for judging whether said external memory unit is capable of storing data when said judging means judges that said predetermined kind of data are not stored in said external memory unit, said third judging means including means for writing test data to said external memory unit, means for reading said test data from said external memory unit and means for comparing said test data read from said external memory unit with said known test data whereby to check the integrity of said external memory unit.

Claim 3

The data processing device according to claim 1, which further comprises printing means coupled to said data processing device for printing at least the data stored in said external memory unit.

Claim 4

The data processing device according to claim 1, wherein said predetermined kind of data comprises download data.

Claim 5

The data processing device according to claim 1, wherein said external memory unit comprises a RAM card having a back-up power supply unit.

Claim 6

The data processing device according to claim 1, wherein said external memory unit comprises an EP-ROM.

Claim 7

The data processing device according to claim 1, wherein said discriminating means comprises a converting mechanism for converting a voltage at a predetermined position in said data processing device to grounded voltage when said discriminating means determines that said external memory unit is coupled to said data processing device.

Claim 8

The data processing device according to claim 6, wherein said converting mechanism comprises an electrical circuit by which said voltage at said predetermined position is connected to ground through a predetermined resistance value if said external memory unit is coupled to said data processing device.

Claim 9

A printing device, comprising at least an internal memory unit for storing data to be printed and a printing mechanism for printing at least the data stored in said internal memory unit on a printing sheet, said printing device being attachably and detachably coupled to an external memory unit to which data are written and from which data are read, said external memory unit storing data even when not coupled to said printing device, said printing device further comprising: discriminating means for determining whether said external memory unit is coupled to said printing device; judging means for judging if a predetermined kind of data are stored in said external memory unit when said discriminating means determines that said external memory unit is coupled to said printing device; another judging means for judging if said predetermined kind of data stored in said external memory unit are usable when said judging means judges that said predetermined kind of data are stored in said external memory unit, said another judging means including means for performing a sum check on said predetermined data and comparing said sum check result with a sum result stored in said external memory unit; error indicating means for indicating that said predetermined kind of data are not usable when said another judging means judges that said predetermined kind of data are not usable; and, third judging means for judging whether said external memory unit is capable of storing data when said judging means judges that said predetermined kind of data are not stored in said external memory unit, said third judging means including means for writing test data to said external memory unit, means for reading said test data from said external memory unit and means for comparing said test data read from said external memory unit with said known test data whereby to check the integrity of said external memory unit.

Claim 10

A printing device, comprising at least an internal memory unit for storing data to be printed and a printing mechanism for printing at least the data stored in said internal memory unit on a printing sheet, said printing device being attachably and detachably coupled to an external memory unit to which data are written and from which data are read, said external memory unit storing data even when not coupled to said printing device, said printing device further comprising: discriminating means for determining whether said external memory unit is coupled to said printing device; judging means for judging if a predetermined kind of data are stored in said external memory unit when said discriminating means determines that said external memory unit is coupled to said printing device; another judging means for judging if said predetermined kind of data stored in said external memory unit are usable when said judging means judges that said predetermined kind of data are stored in said external memory unit, said another judging means including means for performing a sum check on said predetermined data and comparing said sum check result with a sum result stored in said external memory unit; error indicating means for indicating that said predetermined kind of data are not usable when said another judging means judges that said predetermined kind of data are not usable; and, third judging means for judging whether said external memory unit is capable of storing data when said judging means judges that said predetermined kind of data are not stored in said external memory unit, said third judging means including means for writing test data to said external memory unit, means for reading said test data from said external memory unit and means for comparing said test data read from said external memory unit with said known test data whereby to check the integrity of said external memory unit.

Claim 11

The printing device according to claim 8, wherein said predetermined kind of data comprises download data.

Claim 12

The printing device according to claim 8, wherein said external memory unit comprises a RAM card having a back-up power supply unit.

Claim 13

The printing device according to claim 8, wherein said external memory unit comprises an EP-ROM.

Claim 14

The printing device according to claim 8, wherein said discriminating means comprises a converting mechanism for converting a voltage at a predetermined position in said printing device to grounded voltage when said discriminating means determines that said external memory unit is coupled to said printing device.

Claim 15

The printing device according to claim 12, wherein said converting mechanism comprises an electrical circuit by which said voltage at said predetermined position is connected to ground through a predetermined resistance value if said external memory unit is coupled to said printing device.