CompuServe Thread

Mark, I don't recall seeing a version for the A500 Rev 6A board. Have you looked at your board at all? Does it possibly have jumpers for the change? David

The mod for 1-meg CHIp nearly the same for both the Rev6a, and the rev5 A500. First, locate the Agnus jumper (between the CPU & Agnus). This is jumper JP-2. It will look like three small square solder pads. The pads numbered 2 & 3, (middle & bottom) will already be connected for 512K mode. Cut the sodler trace connecting them, and connect pads 1 & 2, (middle & top). This will set the Agnus for 1-meg mode. — Next you need to add another 512K bank of CHIP RAM. This is best done with the A501-slot. You will need a CBM A501 expander, or any third party expander that *can* be re-configured as CHIP. On the rev.6 motherboard there is already a jumper for setting the A501 slot as CHIP. This jumper is JP-7. It is located directly in front of the 56-pin A501 slot. To configure the A501 as SLOW-Fast RAM: pads 2 & 3, (middle & bottom) are connected. Cut the trace to reconfigure the A501 as CHIP. (DON'T solder the top & middle pads! I believe…) — DON'T do anthing to the Gary. There is a BAD set instructions floating around that tells you to pull one of the Gary's pins out of the socket. This is WRONG, this is pin #32, which connects to pin #32 of the A501. It is used to tell whether the A501 is to be SLOW or CHIP. This is controlled by the JP-7 jumper on the rev6, and by a trace on the rev.5. — If you already have 1-meg on the motherboard there is one more pad to cut. If you have only 4 RAM chips (& 4 empty "spots") don't worry about this jumper. Ron. – ap'ing with AP. (Eagles may fly, but weasles aren't sucked into jet engines.)