Service manual

System Interconnection
Transputer links are used for command and control between transputers. Interconnections
between boards use small patching cables with either 2 x 3-way link cables or 4-way service
connections. All inter-rack connections are made by 25-way ‘D’-type connectors and
12-pair low capacitance data cable called ‘Tranlinks’. Each Tranlink cable carries four
differential transputer links and two services (Reset, Analyze and Error).
Audio between racks is carried on high-speed serial (TAXI) links.
Transputers and Signal Processors
No audio is processed by transputers. These are used solely for command and control
functions, in a distributed network locally managing a particular part of the hardware.
Signal processing is carried out on cards known as XSPs each having 32-bit dedicated DSPs.
These cards are managed by a transputer which is part of the overall hierarchy, receiving
commands from and reporting back to other transputers in the system.
Audio Path
The MIOS Racks form the heart of the audio I/O system and contain digital and analogue
interfaces as well as local synchronisation. Master synchronisation and timing for the whole
system is generated with the SPS Rack. The MIOS Racks connect to the rest of the system via
an industry standard MADI interface.
Transputer Types and Function
The consoles use a mixture of 16 and 32 bit transputers that each use four 20M bit/s serial
communication links to form a closely coupled control system. Each of the transputer
boards provide RS422 link buffers and the Reset, Analyze and Error network.
The transputers fall into three categories: T2s, T4s and T8s. These are generic types, each
representing various specific devices:
(a) T2
The T2 is a 16-bit processor used mainly for low-level hardware control functions – turning
on LEDs, controlling the small DSPs on the TranDSP and TranSync cards etc. They have just
under 64K-bytes of memory.
(b) T4
T4s are 32-bit devices used for general-purpose processing, each are provided with 4M
bytes of local memory.
Digital Service Manual
Issue 3 Page 4