Floppy-disk controller

Abstract: An apparatus for emulating a floppy disk drive using flash EPROMs. The apparatus transfers data between a floppy disk controller and a flash EPROM memory module, wherein the floppy disk controller operates under a first protocol and transmits requests to write data to a floppy disk in response to address marks. The flash EPROM operates under a second protocol. The invention includes control means compensating for the difference in the two protocols. In addition, the control means provides for the situation when power is terminated during the write process. Furthermore, the invention includes a means for organizing and reorganizing data in the flash EPROM to make most effective and efficient use of the flash EPROM memory module.

Abstract: An emulating data processor includes a host system and an emulating processor with outputs to and inputs from the host system. The emulating processor executes sequences of instructions executable by a PC being emulated, but a host processor independently executes sequences of its instructions which are different from PC instructions. Circuitry monitors the emulating processor outputs and provides information to the host system so that it can emulate the environment of the PC CPU, emulating both memory and I/O devices. The memory accesses of the emulating processor are mapped into the host system memory, so that the host processor is protected from defective PC software on the emulating processor. The display updates of the emulating processor are detected and provide information for the host processor in updating a part of its display which provides the information a PC display would provide simultaneously with the display characteristic of the host system. An input/output processor handles I/O operation requests of the emulating processor, using the host system I/O devices to emulate some of the PC I/O devices. Output operations to the printer may go either to a local printer or to a file for subsequent printing, so a buffer which can be unloaded to either destination emulates the PC printer. Floppy operations may be handled either by a floppy disk controller like that of the PC or by a software controller of a file in host rigid disk memory which may be accessed as a PC floppy disk, so that a data structure containing parameters of the operation is loaded and provided to the appropriate controller. Rigid disk operations are handled by another file in host rigid disk memory which may be accessed as a PC rigid disk, and an appropriate I/O operating system routine is provided so that the emulating processor can pass the operation parameters through to the host rigid disk controller in a group of registers. Keyboard input operations may come either from the host keyboard or directly from a data structure managed by the host processor, in each case converted to PC codes, and another buffer which can be loaded from either source emulates the PC keyboard. The host system emulates the environment of the emulating processor while emulating the user interface of the PC.

Abstract: A system and method are disclosed for executing, in a multitasking operating system, an application program that accesses a protected resource directly without mediation by the operating system. For example, the application can be a backup application and the resource can be a floppy disk drive, QIC tape drive, or other storage device. The method of the invention can be executed in a computer system having a processor, a storage device, and a device control mechanism for controlling operations of the storage device responsively to commands issued by the processor. The device control mechanism can be, for example, a floppy disk controller chip if the storage device is, for example, a floppy disk drive. According to the invention, the processor executes the application program as a task of the operating system. The operating system includes a software component, such as a device driver, for issuing commands to the device control mechanism. The application program has its own component for issuing commands to the device control mechanism. While the application program is executing, the operating system's command-issuing component is temporarily bypassed, and the application program's command-issuing component is used to issue a command to the device control mechanism, which controls an operation of the storage device responsively to the issued command.

Abstract: A compact system unit for personal computers wherein system hardware components are closely integrated and packed resulting in an effective utilization of space. Such compact integration of hardware is facilitated by the arrangement of system hardware components co-planar with each other. The compact system unit incorporates a hard disk and a floppy disk. The floppy disk controller card is co-planar with and plugs directly on to the mother board. A bus expansion card is vertically mounted to the mother board whereby up to two additional optional expansion cards may be incorporated in a parallel formation within the compact system unit. The daughter board is directly mounted to the mother board in inverted orientation.