Microcomputer PC-card having switching circuit for controlling access to memory based on control signals from internal microprocessor on control signals from external PC
AssigneeGemplus Card International
InventorJean-Yves Le Roux
Life of this patent
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Abstract
A memory or PC-cards serve as a large capacity mass memory for replicating floppy disks and other exchangeable magnetic supports. In order to improve these cards, there is added a microprocessor (MPC) with the direct wiring of the operational bus (BD2) of said microprocessor to the card memory (MEM). In this way, the card contains performable programs previously loaded by the computer (PC). Thus, the cards microprocessor functions not only with an internal set program memory, but also with performable programs loaded into the card by the computer. These programs can be modified as needed (provided that the user clearance procedures are respected).
Claims10
An external card (CC) attachable to a computer (PC) comprising:
- a memory (MEM) accessible by said computer (PC through a direct connection on a data bus (BD1) and through a locking circuit (CV) connection on an address bus (AD1);
- a microprocessor (MPC);
- means (BD2, AD2) for directly accessing an instruction program contained in the memory, said means for directly accessing including an operational bus (BD2) of the microprocessor directly connected to an output bus of the memory (MEM);
- a switching circuit (AA) controlled by the microprocessor for supplying control signals (SC) to control performance of the memory (MEM), said switching circuit (AA) based on the control signals received controls access to the memory, either by the control signals from the computer (SC1, SC3) in which the card is inserted or by the control signals from the microprocessor (SC2, SGA);
- and
- said locking circuit (CV) is controlled by a clearance bus (SH) from the microprocessor, enables /authorization/inhibition signals (SC1, SC3) from the computer or an address signal on said address bus (AD1, AD3) passing through this locking circuit (CV) for ensuring access security to the memory (MEM) from the computer.
An external card attachable to a computer comprising
- a connector (CNC) for connecting said card to a computer,
- a memory (MEM),
- a first direct data bus (BD1) and an interruptable address bus (AD1, AD3) joining said connector and said memory for transfer of data therebetween,
- a microprocessor (MPC) for executing programs stored in said memory,
- a second direct data bus (BD2) and a direct address bus (AD2) each directly joining said memory to said microprocessor,
- a locking circuit (CV) and
- a switching circuit (AA),
- a first control signal bus (SC1) between said connector and said locking circuit (CV) for transmission of control signals from said connector,
- a clearance bus (SH) from said microprocessor to said locking circuit, on which clearance signals from said microprocessor enable or block said control signals from said connector,
- a second control signal bus (SC2) between said microprocessor (MPC) and said switching circuit (AA) for transmission of control signals from said microprocessor,
- a third control signal bus (SC3) between said locking circuit (CV) and said switching circuit (AA), and on which said control signals from said connector enabled said locking circuit (CV) to pass said control signals to said switching circuit (AA),
- said switching circuit (AA) enabling at any time either by the control signals on the second control signal bus (SC2) from the microprocessor (MPC), or the control signals on the third control signal bus (SC3) from the connector in accordance with a switching signal (SGA) received from the microprocessor,
- whereby when the microprocessor (MPC) executes a program stored in memory, the computer to which the card is attached does not have access to said program or to details of execution of said program.
Dependencies are inferred from the claim text.