Abstract: A method and apparatus for configuring a computer in a low-power mode are provided. In the low-power mode, dynamic random access memory is refreshed by a battery powered system in order to maintain the memory contents. Low-power mode is entered by saving an interrupt mask and by disabling interrupts, followed by saving the DMA status, finishing DMA operations, and disabling DMA. After these steps, the I/O state of the machine is saved by saving various I/O registers and ports. A refresh of the memory is forced before the system refresh operations are discontinued.

Abstract: A method and apparatus for configuring a computer in a low-power mode are provided. In the low-power mode, dynamic random access memory is refreshed by a battery powered system in order to maintain the memory contents. Low-power mode is entered by saving an interrupt mask and by disabling interrupts, followed by saving the DMA status, finishing DMA operations, and disabling DMA. After these steps, the I/O state of the machine is saved by saving various I/O registers and ports. A refresh of the memory is forced before the system refresh operations are discontinued.

Abstract: A hand held computer of a type used for such activities as taking inventory, recording signatures on delivery, keeping a route agenda, etc. has a large screen and preferably is without a built in keyboard. The tablet type computer is thin in profile, light in weight and is easily carried and used. Programming in the computer enables an operator to select from various forms available for display on the screen, enables character recognition for items printed on the screen using a conductive stylus, enables the recording in memory of signatures, graphics or any other material entered on the screen, and enables other convenient functions. Certain preferred features of the computer enable it easily to be converted into a full function desk top computer with a keyboard, expansion module and stand.

Abstract: A method and apparatus for configuring a computer in a low-power mode are provided. In the low-power mode, dynamic random access memory is refreshed by a battery powered system in order to maintain the memory contents. Low-power mode is entered by saving an interrupt mask and by disabling interrupts, followed by saving the DMA status, finishing DMA operations, and disabling DMA. After these steps, the I/O state of the machine is saved by saving various I/O registers and ports. A referesh of the memory is forced before the system refresh operations are discontinued.

Abstract: A system for providing keystroke data to an application program without utilizing a keyboard that simultaneously displays application program graphics and a keyboard representation on different segments of a screen. Keys are selected by touching the screen at the location of the graphic representation of the key on the screen. The system is transparent to the application program.

Abstract: A hand held portable computer is secured to a peripheral computer component or expansion module in a snap-on arrangement which automatically effects engagement of bus connectors between the two components. The hand held computer has four openings in its back or under side. Two of the slot-like openings have fittings within them or are so shaped as to receive L-shaped or hook-shaped brackets of the peripheral component. The brackets may be inserted in the slot openings when the computer and the expansion module are held obliquely angled with respect to each other. The computer is then swung down until its back or under side engages against the top of the peripheral component, whereupon a pair of protruding hook members extending at the top surface of the peripheral component engage the computer and snap into locking engagement in the adjacent slot openings. The bus connection is made when the two components are brought together.