Texas Instruments 990 Operation Manual page 183

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945255-9701
.PP.RI,1,4,400
and
.PP,SW,4
and
.PP,RC,4,l,l ,8, 14, 1
with
.PS,MOB4,ROB4
7.7.7 EXAMPLE 7. Twenty-four 4-bit fields are arranged in 16-bit words as shown in the illus-
tration. These 24 fields are to be programmed repetitively in the first 384 four-bit words of a
512
X
4 PROM with characteristics similar to a TI SN74S287 (two 287s with a programming
adaptor card to make them appear as a 512 X 4 device). Refer to figure 7-7.
Assume that this programming sequence is not standard ..
Command
.PP,MI,1,6,3
.PP,MI,2,10,8
.PP,MI,3,0,10
,
.PP,RI, 1,4, 180
.PP,SW,4
Commentary
Level one memory mapping (go across
word).
• Increment 6 bits
• 3 times
Level two memory mapping (step from
word to word).
• Increment 16 bits
• 8 times
Level three memory mapping (provide
repetitions of memory data configuration).
• Increment Obits
• 16 times
Level one ROM mapping
• Increment 4 bits
• 384
(=
16·X 8 X 3) times
Program four bits at a time.
7-33
Digital Systems Division .