First public commit.

lenser/pet/viewer/viewer.s

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+; Commodore PET screen viewer (6502).  Copies PAGES*256 bytes of precomputed
+; screen codes from DATA into the PET screen RAM at $8000, then loops.  The PET
+; video hardware continuously displays $8000 as text, so the picture stays up.
+;
+; #defines from viewer/assemble.py --  DATA = source address, PAGES = 256-byte
+; pages to copy (4 for 40-col / 1000 bytes, 8 for 80-col / 2000 bytes).
+
+        * = $0420
+
+src = $fb
+dst = $fd
+
+start:
+        lda #<DATA
+        sta src
+        lda #>DATA
+        sta src+1
+        lda #$00
+        sta dst
+        lda #$80
+        sta dst+1               ; dest = $8000 (screen RAM)
+        ldx #PAGES
+        ldy #$00
+cp:
+        lda (src),y
+        sta (dst),y
+        iny
+        bne cp
+        inc src+1
+        inc dst+1
+        dex
+        bne cp
+hang:
+        jmp hang