System Overview; Hardware Configuration - ZiLOG Z80-RIO Operating System User's Manual

1.2 SYSTEM OVERVIEW
1.2.1 HARDWARE CONFIGURATION
The RIO Operating System is designed to operate with the 4K
PROM in either the Zilog Micro Computer System (MCZ) or
Development System (ZDS). A minimum configuration of 32K
(lK=1024) of random access memory, one disk drive, and a
console device is required.
The MCZ 1/20 Zilog Micro Computer System is equipped with
two floppy disk drives. The left drive is designated drive
'2' and the right drive is designated drive '0'. The Zilog
Development System (ZDS) also has two drives, but the
designations are 'I' and '0' for left and right, respectively.
The MCZ 1/35 uses hard disk cartridge and fixed platter drives.
The usual configuration consists of one fixed platter and one
c?rtridge drive, designated '0' and 'I', respectively. The
system will support up to 8 drives.
1.2.2 FILE SYSTEMS
For systems using floppy disks, ZDOS controls the organization
and allocation of the sectors on a diskette. While the basic unit
of disk allocation is the sector, the fundamental structure within
ZDOS is the 'file'. A file consists of zero or more sectors
of data which contain logically-related information. Each
file has a set of attributes including a name of from one
to thirty-two characters, a set of (possibly null)
properties, a type, a subtype, and a record length. The
smallest amount of information that can be read from or
written to the disk is the contents of one sector, but more
efficient operation can often be achieved by grouping from
one to thirty-two contiguous sectors (a complete track)
into one unit which is then read or written together. This
unit is called a 'record' and the number of bytes of data
in the record is the record length. A record may consist
of 1, 2, 4, 8, 16 or 32 sectors; therefore the record
length may be 128, 256, 512, 1024, 2048, or 4096 bytes.
On systems with hard disks, the Disk File System (DFS)
provides a similar file structure. The bulk of the DFS
- 3 -