(LBA) A hard disk sector addressing scheme used on all SCSI hard disks, and on ATA-2 conforming IDE hard disks. The addressing conversion is performed by the hard disk firmware.
Prior to LBA, combined limitations of IBM PC BIOS and ATA restricted the useful capacity of IDE hard disks on IBM PCs and compatibles to 1024 cylinders * 63 sectors per track * 16 heads * 512 bytes per sector = 528 million bytes = 504 megabytes. Modern BIOSes select LBA mode automatically, and work around the 1024-cylinder BIOS limit by representing a hard disk to the OS as having e.g. half as many cylinders and twice as many heads. However, there is still an unbreakable BIOS disk size limit of 1024 cylinders * 63 sectors per track * 256 heads * 512 bytes per sector = 8 gigabytes, but modern OSes (including Windows 9x, Windows NT and Linux) are not affected by it, since they issue direct LBA-based calls, bypassing the BIOS hard disk services completely.
- Logical consequence
noun 1. the relation that obtains between the conclusion and the premises of a formally valid argument
- Logical constant
noun 1. one of the connectives of a given system of formal logic, esp those of the sentential calculus, not, and, or, and if … then …
noun, Logic, Philosophy. 1. anything referred to by an incomplete symbol capable of contextual definition.
- Logical form
noun 1. the syntactic structure that may be shared by different expressions as abstracted from their content and articulated by the logical constants of a particular logical system, esp the structure of an argument by virtue of which it can be shown to be formally valid. Thus John is tall and thin, so John is […]