First public commit.

lenser/atari/viewer/gr9.s

@@ -0,0 +1,39 @@
+; lenser -- Atari GR.9 (GTIA 16-luminance) viewer, self-booting
+; 80x192, 16 shades of one hue.  Appended data from $4000 ...
+;   $4000/$5000  bitmap (4 bits per pixel, 4K split)
+;   $6000        one byte, COLBAK = hue times 16
+;
+; assembled by atari/viewer/assemble.py via xa
+
+        * = $2000
+boot:
+        .byte 0
+        .byte 0                 ; sector count (patched)
+        .word $2000
+        .word binit
+
+cont:
+        lda #$22
+        sta $22f                ; SDMCTL
+        lda #<dlist
+        sta $230
+        lda #>dlist
+        sta $231
+        lda #$40
+        sta $26f                ; GPRIOR = GTIA mode 1 (GR.9)
+        lda $6000
+        sta $2c8                ; COLBAK sets the hue
+#include "awyt.i"
+binit:
+        rts
+
+dlist:
+        .byte $70,$70,$70
+        .byte $4f               ; LMS + mode F
+        .word $4000
+        .dsb 101,$0f
+        .byte $4f
+        .word $5000
+        .dsb 89,$0f
+        .byte $41
+        .word dlist