Start from .bas source code, tokenize it, and embed.

Makefile

@@ -4,9 +4,13 @@
 
 ASM=$(wildcard src/*asm)
 
-vic20term.prg: env $(ASM)
+vic20term.bin: env $(ASM) build/demo.raw
 	dasm src/main.asm -Isrc/ -f3 -T1 -sbuild/vic20term.prg.symbols.txt -obin/vic20term.bin
 
+build/demo.raw: env src/demo.bas
+	petcat -w2 -l 1001 -o build/demo.prg -- src/demo.bas
+	dd if=build/demo.prg of=build/demo.raw bs=1 skip=2
+
 env:
 	mkdir -p {bin,build}
 

README.md

@@ -0,0 +1,9 @@
+- From .prg to .BAS
+```
+petcat -2 -o program.bas -- program.prg
+```
+
+- From .bas to .prg
+```
+petcat -w2 -l 1001 -o program.prg -- program.bas
+```

src/demo.bas

@@ -0,0 +1,73 @@
+   5 print"merry christmas"
+   10 data"vs g3a1g2e6,  c3a1g2e6"
+   12 data"vs d3r1d2b6,  c3r1c2g6"
+   14 data"vs a3r1a2c3b1a2, g3a1g2e4r2"
+   16 data"vs a3r1a2c3b1a2, g3a1g2e5r1"
+   18 data"vs d3r1d2f3d1b2, c6e4r2"
+   20 data"vs c3g1e2g3f1d2, c6c4r2"
+   22 data"vt c3r1c1r1c5r1, c3r1c1r1c6"
+   24 data"vt g3r1g1r1g6, c3r1c1r1c6"
+   26 data"vt f3r1f1r1f6, c3r1c1r1c5r1"
+   28 data"vt f3r1f1r1f6, c3r1c1r1c6"
+   30 data"vt g3r1g1r1g6, c6c5r1"
+   32 data"vt g3r1g1r1g6, c6c4r2"
+   34 data"va e3f1e2c6, e3f1e2c6"
+   36 data"va f6d6, e6e6"
+   38 data"va f4c2a3g1f2, e3f1e2c6"
+   40 data"va f6a3g1f2, e3f1e2c6"
+   42 data"va f6d3f1d2, e6g5r1"
+   44 data"va e4c2e3d1b2, e6e4r2"
+   46 data"x"
+  100 ns%=2:vt=36874:dimn%(ns%,80),tm%(ns%),sp%(ns%)
+  160 fori=0tons%:n%(i,0)=0:next
+  190 sh%=16:cv=2:in$="":c$=""
+  230 gosub800
+  240 ifc$="x"then510
+  250 ifc$<>"v"then340
+  260 gosub800
+  280 ifc$="s"thencv=2
+  290 ifc$="a"thencv=1
+  300 ifc$="t"thencv=0
+  310 goto230
+  340 fr=-1
+  350 ifc$="c"thenfr=225
+  360 ifc$="d"thenfr=228
+  370 ifc$="e"thenfr=231
+  380 ifc$="f"thenfr=232
+  390 ifc$="g"thenfr=235
+  400 ifc$="a"thenfr=237
+  410 ifc$="b"thenfr=239
+  420 ifc$="r"thenfr=0
+  430 iffr=-1thenprint"?";c$;"in";in$:stop
+  440 gosub800
+  450 i%=n%(cv,0)+1:n%(cv,0)=i%
+  480 n%(cv,i%)=val(c$)+sh%*fr
+  490 goto230
+  510 fori=0tons%
+  520 sp%(i)=1:tm%(i)=0
+  550 nexti
+  570 fori=0to4:pokevt+i,8:nexti
+  580 ford=0to1
+  590 fori=0tons%
+  600 j=sp%(i)
+  610 ifj>n%(i,0)then670
+  620 d=0
+  630 nt%=(n%(i,j)/sh%-int(n%(i,j)/sh%))*sh%
+  640 iftm%(i)>=nt%then750
+  650 tm%(i)=tm%(i)+1
+  660 pokevt+i,int(n%(i,j)/sh%)
+  670 nexti
+  680 forj=0to70:nextj
+  690 nextd
+  700 fori=0to4
+  710 pokevt+1,0:nexti
+  730 printfre(x);"bytes left"
+  740 sys49148
+  750 sp%(i)=j+1
+  760 tm%(i)=0:goto600
+  800 ifc$="x"thenreturn
+  810 iflen(in$)=0thenreadin$
+  820 c$=left$(in$,1)
+  830 in$=right$(in$,len(in$)-1)
+  850 ifc$=" "orc$=","thengoto800
+  860 return

src/main.asm

@@ -154,9 +154,10 @@ message:
 
 ; https://www.commodore.ca/manuals/funet/cbm/vic20/demos.basic/unexpanded/Stillenacht.prg
 demo_start:
-    .incbin "res/stillenacht.raw"
+    .incbin "build/demo.raw"
 demo_end:
 DEMO_LEN SET demo_end - demo_start
+    ECHO DEMO_LEN
 
 . = $bffc
     jmp coldstart