mmdf@ee.udel.edu (The Mailer) (09/24/90)
There was a recent request on how you can take advantage of the Fatter Agnus chip on A500s. If you just buy the chip & plug it in, It will do nothing. A couple of simple board cuts & one jumper lets it use your A501 memory to expand your available chip memory to 1MB, which presumably is why you bought the chip in the first place. Incongruously, the A500P I just bought came with the Fatter Agnus, but it was not fixed to use the 1MB chip ram space, even though it came with an A501. (BTW, this was a great deal, package includes A500, A501, and AmigaVision for under 600.) Anyway, here are the details, implement at your own skill & risk: Assuming A500 motherboard Rev. 5 (this number near the floppy): Redo jumper JP2, near pin 17 of the ROM. Cut existing on-board jumper, solder in alternate pads. Cut vertical trace (component side of board) which terminates near board via near pin 35 of the A501 expansion connector. It is the second-closest trace to this connector. I've done this twice, both times successfully on the first try. It's great for chip-ram hungry programs like MandelZoom, or DPaint. Gopher it! J. Glomph Black, black@micro.LL.mit.edu
collins@Alliant.COM (Phil Collins) (09/27/90)
REMEMBER!!!! This procedure voids the Warranty! Make sure the computer is out of warranty. Commodore does not recomend this procedure.