1 'MAXRAM.100 by Mike Safonov 70506,1472
2 'This program installs a 51 byte patch of machine code which changes MAXRAM.
3 '
4 'Programmers notes:
5 'This program uses the RST7 hooks in the M100 ROM at 16643 and 7592
6 'to alter the function of the BASIC statements CLEAR and MAXRAM.
7 'See Bob Anderson's HOOKS.100 for further details on RST7 hooks.
8 '
10 CLS:PRINT@8,"MAXRAM.100 program loader"
11 PRINT@81,"HIMEM is currently at ";HIMEM
12 PRINT"Do you want it just below HIMEM (Y/N) ";:A$=INPUT$(1):PRINT
13 IFA$="Y"ORA$="y"THEN TA=HIMEM:GOTO100
14 INPUT"End address+1";TA:IFTA<32768+51ORTA>62960THEN14
100 AD=32755:M=64218:GOSUB200:M=64220:GOSUB200' reset existing CLEAR & MAXRAM RST7 hooks to coldstart values
110 PRINT"MAXRAM machine code installed from"TA-51"to"TA-1:PRINT"Existing code beginning"STR$(TA)" protected"
120 T=TA-51:IFHIMEM>TTHENCLEAR256,T:T=HIMEM
122 FORI=1TO40:POKET+I,PEEK(16644+I):NEXT' copy part of CLEAR routine from ROM
130 POKET,193:FORI=41TO50:READA:POKET+I,A:NEXT' add some custom machine code
140 AD=T:M=T+46:GOSUB200' poke new MAXRAM value into CALL T routine
141 AD=T+1:M=T+39:GOSUB200' poke new MAXRAM+1 into CALL T+44 routine
142 AD=T:M=64218:GOSUB200' set hook RST7 0 in CLEAR routine to CALL T
143 AD=T+44:M=64220:GOSUB200' set hook RST7 2 in MAXRAM routine to CALL T+44
150 PRINT"New MAXRAM="MAXRAM
160 END
200 AH=INT(AD/256):AL=AD-256*AH:POKEM,AL:POKEM+1,AH:RETURN
300 DATA195,45,65,193,33,0,0,195,173,29