Programmable calculator including means for programmably controlling magnetic storage units

摘要

An adaptable programmable calculator is provided by employing modular read-write and read-only memory units capable of being expanded to provide the calculator with additional program and data storage functions oriented towards the environment of the user, a central processing unit, and an input-output control unit capable of bidirectionally transferring information between the memory or central processing units and a number of input and output units. The memory, central processor, and input-output control units are controlled by a microprocessor included in the central processing unit. The input and output units include a keyboard input unit with a plurality of sections capable of being defined by plug-in read-only memory modules and stored programs added by the user, a magnetic card reading and recording unit capable of bidirectionally transferring information between an external magnetic card and the calculator read-write memory unit, a solid state output display unit capable of displaying every alphabetic and numeric character and many other symbols individually and in a line of one or more alphameric statements, and a printer unit capable of printing on thermally sensitive paper every alphabetic and numeric character and many other symbols individually and in alphameric statements or messages. Programs, data, or a combination thereof may be transferred between the calculator read-write memory and an external magnetic card. The keyboard input unit includes LOAD and RECORD keys for entering statements into the calculator read-write memory to control operation of the magnetic card reading and recording unit during execution of a program stored in the calculator read-write memory. Programs transferred from the calculator read-write memory to an external magnetic card contain an indication of the current plug-in read-only memory module configuration of the calculator. Subsequent loading of a program from an external magnetic card at a time when the plug-in read-only memory module configuration of the calculator is different generates an error message for the user. A message is visually displayed to request that the user insert an additional magnetic card during those loading and recording operations involving the transfer of a large program or block of data whose size exceeds the storage capacity of a single magnetic card.