The MicroMainframe 5150 and 5150T are two older expanded memory boards for PC compatible computers. They make it possible to exceed the 640k RAM limit.

According to the 1988 Tandy Computer catalog, the 5150 enables up to 2MB of LIM/EMS RAM to be added to a PC, including the Tandy 1000, 1000SX, and 3000HL. It was priced at $229.95 USD.

A more recent catalog (1997) from DCS Industries listed the 5150T for $159 (or $199 with 2MB RAM installed). It stated that this board would work in the PC-XT and most Tandy 1000 series models.

Basically, this Micro-Mainframe product is a desirable item for adding 1-2 megabytes of RAM to an older computer, if you can still find it.