Looking for PC/XT RAM test program / burn-in diagnostics

I have a DIY 8088 computer, an Xi 8088, that just started throwing a post code that it's having issues passing its lower RAM test. This particular build uses 512K static ram chips. I replaced the lower SRAM chip and the error went away, but I'm skeptical it's really fixed (the SRAM that "failed" wasn't vintage, it was a new manufacture).

So, I'm looking for something that can do a memory stress test. Something that will perform sequential read/write tests, random read/write tests, etc., to stress the memory subsystem and prove to me that it's actually fixed. I'm running DOS, so I'm looking for a DOS program.

Does any one have a recommendation of such a program?

Thanks,
Scott