I keep reading that when it was first released, there was a variant of the IBM PC model 5150 that had only 16KB of RAM installed. From a hardware perspective, this would clearly work - the 5150 motherboard had sockets for 4 banks of 4116-type DRAM chips, and switches to select RAM size that did go down to 16KB, but from a software perspective I really can't see how this could possibly have worked.

As recently discussed, the PC's BIOS loads boot code at address 0000:7c00 - i.e., at the top of the 32KB section of memory. On a system with only 16KB installed, this clearly won't work, so how could a 16KB system boot? Or was it only possible to use such a system with ROM BASIC?