Service manual

Reset and Services

Reset

Reset occurs

(a) at power-up

(b) from the reset switch on the SPS Control Card

program group)

(d) clicking the Reset button in the Desk Explorer program (available in the Encore

program group)

Reset propagation may be checked using the red RST LEDS on each card: the link topology

drawings show the propagation of reset through the system.

When a transputer receives a reset signal it assumes the data that follows is its program

which it automatically executes. If a link has not been correctly terminated, noise at the

differential input may cause incorrect program data to be received and subsequent boot

failure. This condition is identified by activity on any of the four green link LEDS immediately

after receiving a reset signal. Any such activity must by corrected by ensuring the correct

termination plugs are present and that all parts of the system are powered up.

Services

Reset is just one of three “services” connections: the other two are “Analyze” and “Error”.

The Error signal propagates “up” through the hierarchy notifying higher level transputers of

faults on the sub-system, whereas Analyze and Reset flow “down”. Analyze is used during

system development to halt transputer operation while preserving current status

information. Four services connections are provided on each card, each consisting of Reset,

Analyze, and Error (RAE). Logic on the card provides one “up” service channel and three

“down” channels which normally parallel the links, although there are exceptions.

Digital Service Manual

Issue 3 Page 6