System information

hard disk: Rigid, platter-like, magnetic disk sealed in a container. A hard disk stores more
information than a floppy disk.
hardware: Physical components of a computer.
hexadecimal notation: Notation for base 16 values using the decimal digits and letters A, B, C,
D, E, and F to represent the 16 digits. Hexadecimal notation is often used to refer to binary
numbers. A binary number can be easily expressed as a hexadecimal value by taking the bits in
groups of 4, starting with the least significant bit, and expressing each group as a hexadecimal
digit, 0-F. Thus the bit value 1011 becomes 0BH and 10110101 becomes 0B5H.
hex file: ASCII-printable representation of a command, machine language, file.
hex file format: Absolute output of ASM and MAC for the Intel 8080 is a hex format file,
containing a sequence of absolute records that give a load address and byte values to be stored,
starting at the load address.
HOME: BIOS entry point which sets the disk head of the currently selected drive to the track
zero position.
host: Physical characteristics of a hard disk drive in a system using the blocking and deblocking
algorithm. The term, host, helps distinguish physical hardware characteristics from CP/M's
logical characteristics. For example, CP/M sectors are always 128 bytes, although the host sector
size can be a multiple of 128 bytes.
input: Data going into the computer, usually from an operator typing at the terminal or by a
program reading from the disk.
input/output: See I/O.
interface: Object that allows two independent systems to communicate with each other, as an
interface between hardware and software in a microcomputer.
I/O: Abbreviation for input/output. Usually refers to input/output operations or routines handling
the input and output of data in the computer system.
IOBYTE: A one-byte field in page zero, currently at location 0003H, that can support a
logical-to-physical device mapping for I/O. However, its implementation in your BIOS is purely
optional and might or might not be supported in a given CP/M system. The IOBYTE is easily set
using the command:
STAT <logical device> = <physical device>
The CP/M logical devices are CON:, RDR:, PUN:, and LST:; each of these can be assigned to
one of four physical devices. The IOBYTE can be initialized by the BOOT entry point of the
Appendix H : Glossary CP/M Operating System Manual
H-11