Statusregister 0

By reading Statusregister 0 the source(s) of a transputer event that occurred can be determined: when a bit/flag is set the corresponding event occurred. By writing with bits set to '1' the corresponding Statusregister bits/flags will be reset. Table 5 lists the bit position of these event flags. For details about how to handle events see section 6 on event handling.

The following event flags are defined:

• intl : VME interrupt,
• berr : VME bus error,
• xerr : external error signal (external input),
• xevnti0 : external event signal (external input)
• xevnti1 : external event signal ('xevnto1' of other transputer on
  2TP-VME),
• timeout : dynamic memory refresh timeout; the refresh-timeout-
  watchdog detected a cycle that lasted too long and
  forced the cycle to end to ensure the dynamic memory
  is refreshed,
• nzero : a test flag that can only be set and reset under software
  control.

Flags berr, xerr, xevnti0 and xevnti1 are set by edge sensitive signals and cannot be set again before they have been reset. Flags intl and timeout are level sensitive, which means that if the input signals are still active resetting the flag has no effect.

 
Table 5: Definition of bits in Statusregister 0.