Acorn FileStore E01, Руководство по обслуживанию

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Chapter 2
FileStore Service Manual 6
2. E01 Specification
This chapter gives details of the main features of the E01 unit, including electrical
specifications for the interface ports.
2.1 General specification
Within the E01 unit are two
3.5”
floppy disc drives, a switch mode power supply unit (PSU)
and a Fileserver disc drive PCB. The PSU su5V and +12V rails and meets BS5850.
The file server disc drive PCB contains 64K of RAM and 64K of ROM .(two 27256
EPROMs), a Real Time Clock with battery backup, a floppy disc controller, an Econet
Interface and a printer interface. The microprocessor is a 65C102 device, running at 2MHz,
which provides the processing required.
The ROM contains the operating system, filing system and Econet code needed to run the file
server. The 64K of RAM and ROM are never in the memory map at the same time. On power
up the ROM is read and it copies its file server code into the memory map. At the completion
of this exercise the memory map is almost totally resident in RAM.
Two
3.5”
discs are also supplied with the unit: the Master lib disc (containing programs used
to run FileStore) and the data disc (for users‘ own files).
A Real Time Clock circuit incorporating the 146818 RTC is used to provide the information
to allow date stamping of files and also to offer the facility of the Time and Date commands
to users. The RTC is battery backed-up by a rechargeable nickel cadmium cell.
The Econet Interface is based upon the Acorn Econet module. Collision detection and an
internal line biasing circuit are fitted. An Econet clock is generated if no clock is present.
The floppy disc interface is based upon the 2793 disc controller to provide a SA400 interface.
A Centronics-compatible printer interface is driven by a VIA.
A door flap switch (an optical sensor) is used to inform the processor when a disc is about to
be changed and whether to power up in user mode or maintenance mode.
During normal operation, when a user opens the door flap, the processor needs to save the
complete disc maps (held in memory) on the discs before they are removed. It is therefore
essential that when users remove a disc, they first wait until the drive motors have stopped,
indicating that the maps have been stored.
FileStore will normally only accept network filing system commands. To format discs and
issue direct commands to the disc, you must put FileStore into a different mode:
‗maintenance mode‘. (This is to prevent users erasing and formatting discs by mistake.) To
enter maintenance mode, you can either power up with the access flap open, or use the
*FSMODE M command from a user station (see the
FileStore Network Manager’s Guide
for
further details).
For connection to the E20 unit a FileStore expansion bus interface, similar to the BBC
microcomputer 1MHz bus interface, but running at 2MHz, is fitted to the rear of the unit.