Christine5,
On revision 5 A500 models you must make sure that pins 1 and 31 on the Kickstart 2.x or 3.x ROM are connected with a jumper wire.
Revision 6A and 7 A500 models should have the jumper removed (i.e., do not connect pins 1 and 31 on the Kickstart ROM).
On ALL A500 models (Rev 5, 6A, 7) when using Kickstart 1.x ROMs you do not use ANY jumper because 1.x ROMs are 128kbit X 16 ROMs (i.e., 256Kbytes).
The later motherboard revisions (6A, 7) have pin 1 redefined to be the A18 address line. This enables the use of 512KByte ROMs (256kbit x 16) without jumpering.
Hope that helps.
