BeebMaster - BBC Master Econet Terminal




BBC Master Econet Terminal


Here is the Master ET motherboard in a bit more detail. This is an issue 1 motherboard. Interestingly, my own Master ET is also an issue 1 board. Since these are relatively uncommon, it makes me wonder whether ETs were only produced during the issue 1 production run of the Master 128.

The following elements are missing:

- UHF modulator
- analogue port and A-to-D converter chip
- serial port and circuitry
- cassette port, relay and interface circuitry
- audio out port
- serial processor & 6850 Asynchronous Communications Interface Adapter
- two sideways ROM sockets
- "Domesday" SCSI connector
- 1770 disc controller and disc interface circuitry
- modem connector
- 6522 User VIA, although there is a socket for this chip to be added
- all the underside sockets

The Master Econet Terminal has the following differences from the standard Master 128:

- Econet module fitted as standard
- slimmed-down MOS ROM. In the machine above, this appears to be in EPROM. The ROM contains ANFS, BASIC and the MOS only. It does not have DFS or ADFS as there is no disc interface in this machine. Also removed are View, Edit, Viewsheet & Terminal.

The co-processor connectors are retained. Presumably this would be to permit the addition of a 65C102 co-processor to allow the machine to be used as an Econet fileserver. I can't see how that would work, though, because without a disc interface or 1 MHz bus connector, no storage medium can be connected to it.


Photograph courtesy of Ken Hewson.