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STP2002QFP
Fast Ethernet, Parallel Port, SCSI (FEPS) - STP2002QFP
Sun Microsystems,
P_BURST_SIZE:
This field defines the sizes of SBus read and write bursts used by the FEPS
for parallel port transfers. All reads from memory will be one size, either 4,
8, or 1 word (in “no burst mode). SBus writes to memory can be byte, half-
word, or one of the burst sizes given in the table. The FEPS will always use
the largest possible size for writes, which is dependent on P_BURST_SIZE
and the number of bytes that need to be drained. Also, P_BURST_SIZE de-
termines the draining level of the P_FIFO. When the P_FIFO has been filled
with this amount of data, it will always be drained to memory. The sizes given
in Table 20 are in SBus words.
1SBus reads are always one word in no burst mode.
P_DMA_ON:
When set, indicates that the FEPS is able to respond to parallel port DMA re-
quests. Reads as 1 when (P_A_LOADED or P_NA_LOADED) and
P_EN_DMA & !(P_ERR_PEND); otherwise reads as 0.
REV_MIN [2:0]:
FEPS minor revision number.
REV_MAJ [3:0]:
FEPS major revision number. Starts from 2.
Example: for Rev x.y silicon, the {REV_MAJ[3:0], REV_MIN[2:0] = [x,y]}
Table 20:
P_BURST_SIZ
E
RD_BURST_SIZ
E WR_BURST_SIZES FIFO_Draining_Level
00 4 words 4 words 4 words
01 8 words 4, 8 words 8 words
10 No bursts1No bursts 1 word
11 Reserved Reserved Reserved