Nitpick: It's essentially impossible that a 486 would come with 64KB of RAM. My 8088 XT clone in '88 came with 640KB. 4-16MB would be more common for the time.
"The confusion likely stems from the various limits which existed when running qbasic in real mode on a 486. Conventional memory was limited to 640kb. Access to higher amounts of memory either required switching to protected mode or using XMS. Additionally, there was the segmentation limit of 64k for pointers, which may have limited things in qbasic."