Path: utzoo!censor!becker!doug!douglee From: douglee@doug.UUCP (Doug Lee) Newsgroups: comp.sys.amiga Subject: A500 w/Fatter Agnus Message-ID: <01904.AA01904@doug> Date: 4 Feb 90 00:56:16 GMT Followup-To: comp.sys.amiga Lines: 31 seamus@bucsf.UUCP (Jeff Rizzo) writes: >A question for the net... I've heard folks say it can be done, but how >do I get my A500 (it has the 1 Meg Agnus) to recognize the extra 512K >expansion (similar to the A501) as chip RAM? > I would appreciate it if someone could email me a description of the >procedure... What you have to do is connect the A19 pin on the fat agnus chip to the A19 line of the CPU chip. It's presently connected to A23. The other thing you have to do is cut the trace between pin 32 of the GARY chip and the expansion ram connector. Cut it towards the connector as you do NOT want to disconnect the pullup resistor from pin 32 of the Gary chip. There may be jumpers for one or both of these. Some versions of A500 have a jumper labelled JP2 which may be moved to change A23 -> A19. This jumper is labelled J101 on many B2000's. The 2000's also have a jumper position labelled J500 which actually has a solder trace between it. This must be cut. You could place jumper pins here later to make it easy to switch Agnus chips. > Thanks in advance, You're welcome > Jeff Rizzo > seamus@bucsf.bu.edu -- douglee@becker <<>> 416-461-5357