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- PAL20X10 PAL DESIGN SPECIFICATION
- VP4 BIRKNER/KAMZI/UDI 7/14/81
- LINES/SCROL GENERATOR
- MMI SUNNYVALE, CALIFORNIA
- CK /SWAP SCAN0 SCAN1 /INIT /SCAN3 /H255 NC /WRITE /LINE4
- /INCSCR GND /OC /SCROL0 /LINES0 /SCROL1 /LINES1 /SCROL2 /LINES2 /SCROL3
- /LINES3 /INITS /OE VCC
-
- LINES0 := /SWAP*/INITS*LINES0 ;HOLD
- + SWAP*/INITS*SCROL0 ;SWAP WITH SCROL
- :+: /SWAP*/INITS*H255*/LINE4 ;INC (12 DOT LINES)
- * SCAN3*SCAN1*SCAN0
- + /SWAP*/INITS*INCSCR ;INC (LF)
-
- SCROL0 := /SWAP*/INITS*SCROL0 ;HOLD
- + SWAP*/INITS*LINES0 ;SWAP WITH LINES
- :+: /SWAP*/INITS*INCSCR ;INC (LF OR CHAR = 47)
- + INITS ;INITIALIZE
-
- LINES1 := /SWAP*/INITS*LINES1 ;HOLD
- + SWAP*/INITS*SCROL1 ;SWAP WITH SCROL
- :+: /SWAP*/INITS*H255*/LINE4 ;INC (12 DOT LINES)
- * SCAN3*SCAN1*SCAN0*LINES0
- + /SWAP* /INITS*INCSCR*LINES0 ;INC (LF)
-
- SCROL1 := /SWAP*/INITS*SCROL1 ;HOLD
- + SWAP*/INITS*LINES1 ;SWAP WITH LINES
- :+: /SWAP*/INITS*INCSCR*SCROL0 ;INC (LF OR CHAR = 47)
- + INITS ;INITIALIZE
-
- LINES2 := /SWAP*/INITS*LINES2 ;HOLD
- + SWAP*/INITS*SCROL2 ;SWAP WITH SCROL
- :+: /SWAP*/INITS*H255*/LINE4 ;INC (12 DOT LINES)
- * SCAN3*SCAN1*SCAN0
- *LINES1*LINES0
- + /SWAP*/INITS*INCSCR ;INC (LF)
- *LINES1*LINES0
-
- SCROL2 := /SWAP*/INITS*SCROL2 ;HOLD
- + SWAP*/INITS*LINES2 ;SWAP WITH LINES
- :+: /SWAP*/INITS*INCSCR*SCROL0*SCROL1 ;INC (LF OR CHAR = 47)
- + INITS ;INITIALIZE
-
- LINES3 := /SWAP*/INITS*LINES3 ;HOLD
- + SWAP*/INITS*SCROL3 ;SWAP WITH SCROL
- :+: /SWAP*/INITS*H255*/LINE4 ;INC (12 DOT LINES)
- * SCAN3*SCAN1*SCAN0
- *LINES2*LINES1*LINES0
- + /SWAP* /INITS*INCSCR ;INC (LF)
- *LINES2*LINES1*LINES0
-
- SCROL3 := /SWAP*/INITS*SCROL3 ;HOLD
- + SWAP*/INITS*LINES3 ;SWAP WITH LINES
- :+: /SWAP*/INITS*INCSCR ;INC (LF OR CHAR = 47)
- *SCROL2*SCROL1*SCROL0
- + INITS ;INITIALIZE
-
- INITS := INIT*H255 ;INITIALIZATION SIGNAL
-
- OE := /WRITE ;ENABLE THREE STATE OF RAM
-
-
- FUNCTION TABLE
-
- CK SWAP SCAN3 SCAN1 SCAN0 INIT H255 WRITE LINE4 INCSCR /OC
- SCROL3 SCROL2 SCROL1 SCROL0 LINES3 LINES2 LINES1 LINES0 INITS OE
-
- ; I
- ; W L N I
- ; S I H R I C N
- ; W N 2 I N S / I
- ; C A SCAN I 5 T E C O SCROL LINES T O
- ; K P 310 T 5 E 4 R C 3210 3210 S E COMMENTS
- ---------------------------------------------------------------------------
- C X XXX H H X X X L XXXX XXXX H X SET INITIALIZE BIT
- C X XXX L X X X X L HHHH LLLL L X INITIALIZE COUNTERS
- C L XXX L L X X L L HHHH LLLL L X INITS = L
- C L HHH L H X L L L HHHH LLLH L X INC LINES, HOLD SCROL
- C L HHH L H X L L L HHHH LLHL L X INC LINES, HOLD SCROL
- C L HHH L H X L L L HHHH LLHH L X INC LINES, SCAN = 11
- C L HHH L H X L L L HHHH LHLL L X INC LINES, SCAN = 11
- C L XXX L H X X H L LLLL LHLH L X INC LINES & SCROL: LF
- C L XXX L X X X H L LLLH LHHL L X INC LINES & SCROL: LF
- C L XXX L L X X L L LLLH LHHL L X HOLD LINES & SCROL
- C H XXX L L X X L L LHHL LLLH L X SWAP LINES & SCROL
- C L XXX L X X X H L LHHH LLHL L X INC LINES & SCROL
- C X XXX X X L X X L XXXX XXXX X H SET OE
- C X XXX X X H X X L XXXX XXXX X L CLEAR OE
- ---------------------------------------------------------------------------
-
- DESCRIPTION
-
- "SCROL" AND "LINES" ARE COUNTERS AND POINTERS TO THE RAM. "LINES" IS A
- POINTER TO THE LINE THAT IS READ FROM THE RAM. "SCROL" IS A POINTER
- TO THE LOCATION IN THE RAM WHERE A NEW LINE CAN BE STORED. BOTH OF THEM
- COUNT UP TO A MAXIMUM OF 16 LINES.
-
- THE BIT "SWAP" ENABLES THE TWO COUNTERS TO TALK TO THE SAME ADDRESS LINES
- OF THE RAM.
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