Abstract: A data field having a variable number of zero-level bits is read by a bus in a digital system, wherein the bus is pumped by writing all logical "one" bits onto the bus lines just before they are read. The unused bits will then be still in a logical "one" state, i.e. a known value, rather than floating or at an indeterminate value. A program for performing this operation in a computer uses steps to prevent other operations such as refresh cycles or interrupts from being interposed between the write and read cycles. A CPU may use this method to read a system identifier value upon boot-up, for example.

Abstract: A computer system which can receive boot information over a parallel or serial port. The ports are inspected for activity prior to attempting to boot from a floppy or hard disk. If there is activity on the port the sequence being received is read and compared to a predetermined identification sequence. If a match is made, an acknowledgement character is transmitted. A communication sequence commences to transfer the boot information over the link. After the transfer is complete, the boot information is executed. The serial transfer utilizes the conventional serial lines, while the parallel transfer is performed a nibble at a time. This nibble mode allows use of only outputs to inputs to avoid dual source driving problems.

Abstract: A computer system uses a random access memory to store memory characteristic information, such as noncacheable status. The memory is coupled to the processor address lines to produce an output representative of the memory address block, the output used as appropriate, for example by the noncacheable address input of a cache controller. Latches are used to store programming mode, write or read operation and data values. The reading and writing of the random access memory is performed without disturbing the main memory.

Abstract: A keyboard controller or interface with scans entered key sequences for a key sequence activating a keyboard lock feature. A password and particular hot key are loaded by the system microprocessor. The keyboard interface then scans untl the designated sequence is activated. All keyboard activity is blocked from the system microprocessor until a password sequence is entered. Codes releasing some of the key strokes in the activation sequence are transmitted and normal operation, including activation sequence scanning, resumes. The password mode may be directly activated on command from the system microprocessor.

Abstract: In a token-based local area network, the token may be selectively redirected out of its normal even rotational sequence among all of the active nodes of the network to pass the token more frequently through a priority group of nodes than through a non-priority group of nodes. The priority group is more likely to have messages to initiate from either a numerical or immediacy standpoint, compared to the non-priority group which is less likely to have messages to initiate. When token redirection is not desired, the token is passed in this normal even rotational sequence. Despite redirection, the token is still passed through all of the active nodes on the network in a periodic manner so as to assure normal network activity. Multiple messages can be initiated from a single node before the token is passed to any other node.

Abstract: A power-on password security function for a digital computer system allows the system software to distinguish between authorized and unauthorized users. Safeguards are made against corruption of password data which could lead to lock-out authorized users, and redundant checks allow the security function to operate even when first-level checks fail. The battery-powered RAM storage area used to hold the password when the system is turned "off" is protected against being accessible by unauthorized users when the system is turned "on".

Abstract: A computer having an improved keyboard/auxiliary device interface controller which supports the selective restriction of user interaction with the computer system, while maintaining the full internal functionality of the host/peripheral interface. A "password lock mode" of the improved controller prevents users from gaining unauthorized access to the computer system, but still application and operating system software can continue to issue commands to and receive responses from the otherwise disabled peripheral devices. The improved controller does not require modification to the conventional keyboard/auxiliary device hardware.