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A.3 Multiblock Capable Slaves.

A Multiblock Capable Slave may be Configured as a Primary Link, a Middle Link or an End Link and then participate in Multiblock operations. It may also be configured to not be active in a Multiblock Group.


A Multiblock Capable Slave shall be capable of operating in Multiblock Mode at any position in a Multiblock Group. Its configuration shall be defined by the value of CSR#xxyy,zz as shown in Table 31. RB or Reset (CSR#0) shall set these bits to 00. RB or Clear Error (CSR#0) shall have no effect on the state of these bits.

Multiblock Capable Slaves may have any other normal attributes of FASTBUS Slaves.


A Multiblock Capable Slave shall at all times respond to any normal FASTBUS operations for which it is designed.

Data in a Multiblock Capable Slave is located in (DSR) #1 which is FIFO-like in operation, i.e., many words of data may be read or written in sequence without changing the NTA. During normal operations an end-of-buffer is indicated by an SS=2 response.


Data accessible in Multiblock Mode shall be accessible through DSR#1 which shall act as a FIFO-like device.

In the Primary Link, DSR#2 is a FIFO-like virtual location through which DSR#1 of each of the Slaves in the Multiblock Group is be accessed in turn.


A Primary Link shall contain a virtual DSR#2 which emulates a large buffer containing all the DSR#1 buffers of Slaves in its associated Multiblock Group.

An attempt to access DSR#2 in a Multiblock Capable Slave that is not configured as a Primary Link should result in an SS=6 error.

A Multiblock activity indicator provides as a simple visual indication of response in Multiblock Mode.


Immediately below the Module Activity Indicator(s) a Multiblock Capable Slave shall have a second yellow LED which shall be lit by a monostable whenever the Module is transferring data in Multiblock Mode.



Next: A.4 Multiblock Control Signals. Up: A PRELIMINARY SPECIFICATION FOR Previous: A.2 Multiblock Configuration.


A.Daviel,TRIUMF