VIC Contractor

 COMPUTE! ISSUE 37 / JUNE 1983 / PAGE 224

Vic Contractor
Peter Lear

Using these two programs, you can make expansion memory invisible to the VIC so unexpanded programs can be run without removing the cartridge. There's also a short program to access the 3K expansion area usually lost when an 8 or 16K cartridge is employed.

Do you have some extra memory for your VIC that you don't always need? Are you tired of yanking out that cartridge and putting it back? Do you fear, that your edge connector might eventually wear itself out? Here's the solution. Use these methods to "mask" cartridges from your VIC.
1. The 3K expansion. This is easy, because all that happens is that an empty memory block is filled. To forget this memory, just type in the following:

POKE 44,16:POKE 4096,0:NEW

   2. The 8K, 16K or 24K expanded VIC. This is not as easy because not only has empty memory been filled in, but the VIC's screen has also moved. BASIC now begins at 4608 ($1200), and the screen is where BASIC once was, 4096 ($1000). Finally, the color locations for the screen now start at 37888 ($9400). To fix all these alterations so that the VIC is unexpanded, type in Program 1. Save a copy before running it (otherwise you will need to type it again to use it). To get the memory back, just do a cold start with SYS64802.
   3. The 3K in addition to 8K or 16K or 24K expanded VIC. With this setup, you cannot see the 3K cartridge as BASIC memory. To make this arrangement into a nonexpanded VIC, just use Program 1. The 3K block will still be accessible for machine language. As with the other cartridge arrangements, you also have access to any filled-in memory blocks solely for machine language. Some applications require that the 3K block be part of BASIC. Program 2 accomplishes this. Rather than type in the whole thing, just modify Program 1.
   For some VIC owners with expansion boards, these programs are not necessary since the boards themselves have switches which do the same thing. But these programs are useful for VIC owners whose boards do not provide such switches and for those without boards.
   Note: Super Expander owners should change the following lines of Program 2:

130 POKE51,120:POKE52,29:POKE55,120:POKE56
    ,29:POKE646,6
150 PRINT"6519 BYTES FREE"

(This allows the function key labels to be protected.)

Program 1: Reset To Unexpanded VIC

100 POKE36866,150:POKE648,30:POKE36869,240
110 FORJ=217TO228:POKEJ,158:NEXT
120 FORJ=229TO250:POKEJ,159:NEXT
130 POKE51,0:POKE52,30:POKE55,0:POKE56,30:
    POKE646,6
140 PRINT"{CLEAR}**** CBM BASIC V2 ****"
150 PRINT"3583 BYTES FREE"
155 POKE243,154:POKE244,150:POKE642,16:POK
    E644,30
160 FORI=4096TO5000:POKEI,0:NEXT
170 POKE 44,16:POKE46,16:POKE48,16:POKE50,1
    6:NEW

Program 2: Reset To VIC With 3K Expansion

100 POKE36866,150:POKE648,30:POKE36869,240
110 FORJ=217TO228:POKEJ,158:NEXT
120 FORJ=229TO250:POKEJ,159:NEXT
130 POKE51,0:POKE52,30:POKE55,0:POKE56,30:
    POKE646,6
140 PRINT"{CLEAR}**** CBM BASIC V2 ****"
150 PRINT"6655 BYTES FREE"
155 POKE243,110:POKE244,150:POKE642,4:POKE
    643,120:POKE644,29
160 FORI=1024TO1028:POKEI,0:NEXT
170 POKE44,4:POKE46,4:POKE48,4:POKE50,4