Game 4 Unit 5 of 6 1 hr learning time

The Bell in Bars

A column of figures isn't a picture. Walk the array and POKE each count as a bar of solid blocks straight to the screen — scaled to fit, on black, labelled beneath. The bell you read in numbers becomes a bell you can see.

83% of Tally

The numbers tell the story, but a row of figures isn't a picture. The whole promise of Tally is to see the bell — and you already know how to draw on the C64 by hand. In Skyline you POKEd blocks into screen memory to build towers. Here you do the same, but the height of each column comes from the data: one bar per total, as tall as its count.

10 PRINT CHR$(147)
20 POKE 53281,0
30 DIM T(12)
40 FOR I=1 TO 1000
50 D=INT(RND(1)*6)+1+INT(RND(1)*6)+1
60 T(D)=T(D)+1
70 NEXT I
80 MX=0
90 FOR F=2 TO 12:IF T(F)>MX THEN MX=T(F)
100 NEXT F
110 FOR F=2 TO 12
120 H=INT(T(F)*18/MX)
130 C=(F-2)*3+3
140 FOR Y=0 TO H-1
150 POKE 1024+(23-Y)*40+C,160:POKE 55296+(23-Y)*40+C,3
160 POKE 1024+(23-Y)*40+C+1,160:POKE 55296+(23-Y)*40+C+1,3
170 NEXT Y
180 NEXT F
190 FOR F=2 TO 12
200 C=(F-2)*3+3
210 IF F<10 THEN POKE 1024+24*40+C,F+48:POKE 55296+24*40+C,1:GOTO 240
220 POKE 1024+24*40+C,49:POKE 55296+24*40+C,1
230 POKE 1024+24*40+C+1,(F-10)+48:POKE 55296+24*40+C+1,1
240 NEXT F
A C64 screen, black background: eleven cyan bars forming a bell, tallest at 7, with the totals 2 to 12 in white along the bottom.
The bell, drawn. Eleven cyan columns rise from the array — tallest at 7, falling away to 2 and 12 — with the totals labelled beneath. The same data as last unit, now a shape you read at a glance.

There's more here than usual, so take it in pieces. Line 20 sets the background black (POKE 53281,0) so the bars stand out. Lines 80–100 find MX, the largest count, so the chart can be scaled: line 120, H = INT(T(F)*18/MX), turns each count into a height where the biggest bar fills 18 rows and the rest fall in proportion — so the picture fits the screen whatever the numbers are.

The drawing is lines 110–180. For each total F, the column C is worked out from F so the bars sit side by side, and the inner FOR Y loop POKEs solid blocks (screen code 160) up the column into screen RAM from 1024, with cyan (colour 3) into colour RAM from 55296 — the same two-write pattern as Skyline, a shape and its colour. Lines 190–240 POKE the totals 2–12 along the bottom row as labels. The result is the bell, drawn by the machine from nothing but counted dice.

Try this

  • Recolour the curve. Change the 3 in the POKEs to colour RAM to 5 (green) or 7 (yellow). The whole bell shifts hue at once.
  • Read the heights. The tallest bar is 7, scaled to fill the screen. Cover the labels and you can still name each total just from how tall its bar is — that's the data made visible.

What's next

The chart is locked to a thousand rolls. In Unit 6 you hand the run count to the player with INPUT — roll 10 for a ragged guess, 1000 for a clean bell, and watch the shape sharpen.