x1pepe, ánimo con el BASIC!!!
Te paso un ejemplo de cómo definir y mover caracteres en SCREEN 2 (era del antiguo foro, y lo he recuperado).
10 REM Inicializo SC2
20 DEFINTA-Z:COLOR15,1,1:SCREEN2,2,0
30 REM Pongo 0 en toda la pantalla
40 FORN=6144TO6911:VPOKEN,0:NEXTN
50 REM Redefino caracteres 3 bancos
60 FORN=776TO879:READA:VPOKEN,A:VPOKEN+2048,A:VPOKEN+4096,A:NEXTN
70 REM Redefino colores 3 bancos
80 FORN=8968TO9071:READA:VPOKEN,A:VPOKEN+2048,A:VPOKEN+4096,A:NEXTN
90 REM * Descomprime y pinta maze *
100 FORN=0TO79:READA:A$=RIGHT$("0000000"+BIN$(A),8):FORM=1TO8
110 VPOKE6144+(N*8)+(M-1)+64,ASC(MID$(A$,M,M))+57:NEXTM:NEXTN
120 READX,Y:VPOKE6144+X+(Y*32),107
130 REM Inicia personaje
140 READP:D=5:PO=P:M=0
150 REM Control
160 A=STICK(0):L=0:V=0
170 IFA=1THEND=1:P=P-32:L=1
180 IFA=3THEND=3:P=P+1:L=1
190 IFA=5THEND=5:P=P+32:L=1
200 IFA=7THEND=7:P=P-1:L=1
210 M=M+1:IFM=2THENM=0
220 IFVPEEK(P)=106THENP=PO:L=0
230 IFVPEEK(P)=107THENV=1
240 VPOKEP,96+D+M:IFL=1THENVPOKEPO,0:PO=P
250 FORT=1TO10:NEXTT
260 IFV=1THEN GOTO 290
270 GOTO 160
280 GOTO280
290 REM Victoria
300 FORT=1TO10:FORM=0TO1:VPOKEP,108+M:FORN=1TO50:NEXTN:NEXTM:NEXTT:END
310 ' Patterns
320 DATA &h18,&h38,&h18,&h3C,&h5A,&h18,&h10,&h10,&h00,&h18,&h38,&h18,&h7E,&h18,&h08,&h08
330 DATA &h18,&h1C,&h18,&h38,&h3C,&h18,&h18,&h1C,&h00,&h18,&h1C,&h18,&h1E,&h18,&h24,&h36
340 DATA &h18,&h38,&h18,&h3C,&h5A,&h18,&h10,&h10,&h00,&h18,&h38,&h18,&h7E,&h18,&h08,&h08
350 DATA &h18,&h38,&h18,&h1C,&h3C,&h18,&h18,&h38,&h00,&h18,&h38,&h18,&h78,&h18,&h24,&h6C
360 DATA &h00,&h00,&h00,&h00,&h00,&h00,&h00,&h00
370 DATA &h81,&h7D,&hEE,&h7E,&hDC,&hFA,&hFE,&h6C,&hFF,&h81,&h81,&h81,&h81,&h81,&h81,&hFF
380 DATA &h18,&h38,&h99,&h7E,&h18,&h18,&h24,&h66,&h00,&h18,&h38,&h99,&h7E,&h18,&h24,&h66
390 ' Colors
400 DATA &h80,&h80,&hA0,&hC0,&hC0,&h40,&h40,&h60,&h60,&h80,&h80,&hA0,&hC0,&h40,&h40,&h60
410 DATA &h80,&h80,&hA0,&hC0,&hC0,&h40,&h40,&h60,&h80,&h80,&h80,&hA0,&hC0,&h40,&h40,&h60
420 DATA &h80,&h80,&hA0,&hC0,&hC0,&h40,&h40,&h60,&h60,&h80,&h80,&hA0,&hC0,&h40,&h40,&h60
430 DATA &h80,&h80,&hA0,&hC0,&hC0,&h40,&h40,&h60,&h80,&h80,&h80,&hA0,&hC0,&h40,&h40,&h60
440 DATA &h00,&h00,&h00,&h00,&h00,&h00,&h00,&h00
450 DATA &h60,&h90,&h90,&h90,&h90,&h80,&h80,&h60,&hF0,&hF0,&h70,&h70,&h50,&h50,&h40,&h40
460 DATA &h80,&h80,&hA0,&hC0,&hC0,&h40,&h40,&h60,&h80,&h80,&h80,&hA0,&hC0,&h40,&h40,&h60
470 ' Map
480 DATA &hff,&hff,&hff,&hff,&ha1,&h11,&h00,&h01,&hbd,&h15,&h7f,&hdd,&h81,&h15,&h40,&h55
490 DATA &hfd,&h14,&h5f,&h55,&h85,&h15,&hd1,&h55,&hf1,&h75,&h1d,&h05,&h9d,&h04,&h05,&hfd
500 DATA &h81,&hfd,&h7c,&h05,&h9f,&h11,&h41,&hfd,&hb0,&h57,&h5f,&h01,&h87,&hd0,&h50,&h7d
510 DATA &hfc,&h57,&hd7,&hc5,&h81,&hd0,&h14,&h15,&haf,&h07,&hd5,&hf1,&ha8,&h20,&h54,&h1f
520 DATA &haa,&hbf,&h05,&hc1,&hba,&ha5,&hfd,&h7d,&h82,&ha0,&h00,&h01,&hff,&hff,&hff,&hff
530 DATA 9,4,6241