pouët.net

Which program can I use to test the "slow RAM" chips in my A500. One of the DRAM chips is probably broken. All programs I've found are Kickstart 2.0 or later:-(

And for some strange reason the memory I seek in Seka at $c0.0000 looks like RAM already.

Maybe sysinfo is what you're looking for? (Keep in mind, it's been twenty years since I last touched an A500. Just trying to be helpful...)
http://aminet.net/package/comm/cnet/SysInfo101
or maybe a newer one?
http://aminet.net/package/util/moni/SysInfo

Actually, I'm not even sure if that first link is what I think it is. Whatever.

I recall "Memory Doctor" was the thing on OCS Amigas, like Memtest86+ is on fucking peecee. Supposedly it is part of "AMI Tools", but maybe this will do as well if you don't need the GUI eye candy:
http://aminet.net/package/util/misc/Amnesia12

Amnesia12 did the job well. Thanks!