etxtomp@eos.ericsson.se (Tommy Petersson) (01/09/91)
In article <24830002@hp-lsd.COS.HP.COM> davem@hp-lsd.COS.HP.COM (Dave K. Martin) writes: >I believe that the A-500 does not have the jumpers on the motherboard that >the A-2000's have. There are some jumpers to be moved and traces to be >cut to allow the new Agnus to access the additional memory. If this is >not done, then the chip will stilll only access 512k. > >When I upgraded my A-2000, rev 4.2, my dealer gave me an instructiion sheet >showing what to cut and jumpers to move. The following is quoted from that >sheet. Any typos, etc are mine :-). > > The new "fatter" Agnus 8372 IC, which can address 1 megabyte of chip ram > will require the:w following modifwing modifications to the A2000 pcg > operation. Without these modifications the IC will adress only 512k of > chip ram and operate only in NTSC mode. > > 1. Locate jumper pad J500 (to the lower left of the 8520 at U301). > This is a 2 pad jumper with a trace connecting the two pads. With a > Exacto knife cut the trace which connects the pads. Be careful not > to allow the blade to slip and cut another trace. Note: see page 9 > of A2000 system schematics, cutting this trace keeps the _EXRAM from > being tied to ground. > > 2. Locate jumper J101 (to the lower right of power connector CN400). > Move shorting block to the left, shorting pins 2 and 3. Note: see > page 13 of A2000 system schematics, this wil enable address line 19 > from the 68000, which controls the 1 meg adress range. > ... and if you want the machine to boot up in PAL, there is one more trace to cut. What I want to know is: If I want to be able to run some old programs that doesn't seem to like my Amiga since I installed the 1Meg Agnus, should I put a switch at jumper pad J500, or do I need to have a three-way switch at J101 as well/instead? I have tried a small program called KillChip, but I still had 1 MB chip memory after I ran that. Maybe I did something wrong, or don't have the correct version? Tommy Petersson etxtomp@eos.ericsson.se