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Data Device Corporation
www.ddc-web.com
BU-6174X/6184X/6186X
F-10/02-300
General Purpose Queue. The Enhanced Mini-ACE/-ACE BC
allows for the creation of a general purpose queue. This data
structure provides a means for the message sequence proces-
sor to convey information to the BC host. The BC op code reper-
toire provides mechanisms to push various items on this queue.
These include the contents of the Time Tag Register, the Block
Status Word for the most recent message, an immediate data
value, or the contents of a specified memory address.
FIGURE 5 illustrates the operation of the BC General Purpose
Queue. Note that the BC General Purpose Queue Pointer
Register will always point to the next address location (modulo
64); that is, the location following the last location written by the
BC message sequence control engine.
If enabled, a BC GENERAL PURPOSE QUEUE ROLLOVER
interrupt will be issued when the value of the queue pointer
address rolls over at a 64-word boundary. The rollover will always
occur at a modulo 64 address.
LAST LOCATION
BC GENERAL
PURPOSE QUEUE
(64 Locations)
BC GENERAL
PURPOSE QUEUE
POINTER
REGISTER
NEXT LOCATION
FIGURE 5. BC GENERAL PURPOSE QUEUE