Microbee Star CP/M Network System Released : 1983
Chapter 0 - Introduction.
The MicroBee Star Network provides a user-friendly CP/M
based system for up to sixteen simultaneous users. A central file
server provides disk storage and retrieval functions for each of
the units (workstations) connected to it. The network software is
configured in such a way that the system is CP/M compatible, and
any of the thousands of CP/M programs available will run on the
workstations.
The network is arranged in the "Star" format. Each of the
workstations is connected directly to the file server. Because of
this configuration, no contention arbitration is necessary and
thus transfer efficiency is not limited by collisions and
retransmission. The network uses an 8-bit parallel bus and
operates at an effective bit rate of 1.28 million bits per
second.
A workstation consists of a standard 64K MicroBee fitted
with a small network interface that plugs into the parallel I/O
port of the MicroBee. The normal Disk Boot Rom is replaced with a
Network Rom, which is similar to the Disk Boot Rom except that
the disk routines have been replaced with Network routines. The
workstations thus retain the monitor and terminal functions of
the Disk Boot Rom.
The file server is also a standard 64K MicroBee, retaining
the normal Disk Boot Rom and having two to four disk drives
attached to it. It also has a 16-way interface board which
connects in a similar fashion to the disk controller board. The
file server may be used as a normal disk MicroBee for software
maintenance purposes when the network is not in use. The file
server cannot be used as a normal CP/M system when the network is
in use.
Printers may be connected to the file server, to
workstations, or to both. Since the parallel interface on the
workstations is used for the network interface, only serial
printers may be connected to a workstation. The file server can
accept one serial and one parallel printer.
Disk space is arranged so that each user may be given a
private, password protected workspace. The workspace is accessed
via the LOGIN program, and appears to the workstation as a
selfcontained disk drive. The workspace is normally set up as
"Drive B", with the system programs such as BASIC, CP, STAT, etc.
resident on "Drive A". Drives C through E are used for storing
workspaces and publicly accessable programs and data. All drives
except "B" are usually write protected. Permission to write onto
the other, public, drives may be given to no station, one
particular station, or any station.
The file server is supplied with the standard CP/M software
with the exception of MOVCPM, and includes the usual MicroBee
transients such as CONFIG, DDFORMAT etc. A network distribution
disk is also supplied. This disk contains the file server
program, configuration programs, as well as LOGIN, LOGOUT, PRINT,
PASSWORD etc.
The MicroBee Star Network provides a low-cost, yet extremely
powerful system that presents a fully featured CP/M station to
each of up to sixteen users. The network is ideally suited to
classroom applications where basic language (Basic, Pascal, etc.)
and wordprocessing facilities are needed. In the office
environment, the multitude of CP/M application programs than can
be run on the network cater for most business needs.
Ref: MicroBee Star Network System Manual. (1983)
David S. McGrath and Paul A. Wilmshurst.
HoneySoft.
4.1 Network Specifications.
Hardware :
Network layout : Star format.
Number of stations : Up to 16.
Printers : 1 serial and 1 parallel printer may
be connected to the File Server,
and 1 serial printer may be
connected to each workstation.
Transmission mode : 8-bit parallel, bidirectional,
asynchronous.
Tranmission levels : TTL.
Handshaking : 2 lines - 1 REQ/ACK line in each
direction.
Cable : 11 conductor untwisted, unshielded.
Length up to 20m.
Transmission rate : 160 Kbytes/second
Data error rate : Better than 1 in lE 7
File Server :
Computer : MicroBee 64K, color or monochrome.
Network interface : 16-way Network Interface Board.
Disk drives : 1 to 4 Standard 390K 5.25" MicroBee
drives. Hard disk and other
capacity drives supported upon
request.
CPU : Z80 3.375 MHz +/- 0.3% clock rate
Workstations :
Computer : MicroBee 64K, color or monochrome,
fitted with special Network boot ROM.
Network interface : Bidirectional buffer/driver term-inates
cable and plugs into the parallel connector.
CPU : Z80 3.375 MHz +/- 0.3% clock rate
Power supply : Isolated from earth.
Software :
Operating system : CP/M running on both File Server
and WorkStations. File Server
cannot be used when Network in use.
Utilities supplied : FS - File Server program.
CREATE - WorkSpace creator.
NETCON - Network configuror.
PRINT - File Server printer driver.
LOGIN - WorkSpace access granter.
ALOGIN - Special version of above.
LOGOUT - WorkSpace closer.
PASSWORD - Password changer.
KEYS - Function keys editor.
SCR - Screen position utility.
Ref: MicroBee Star Network System Manual. (1983)
David S. McGrath and Paul A. Wilmshurst.
HoneySoft.
