Bottom Half - Software interfacing to I/O device hardware which services interrupts related to the device, provides basic configuration and control, monitors status, and buffers I/O data - the Top Half makes a Bottom Half usable for application software.
BSP - Board Support Package, the boot code and basic I/O interface initialization code needed by an RTOS to boot and cycle on an embedded system board.
BSS - uninitialized global C program data - because the data is not initialized, this data need not take up space in non-volatile memory, but must be allocated a data segment in working main memory.
Bt878 - Brooktree Video/Audio encoder which can digitize an NTSC input
Burst Transfer - A bus transaction which involves an initial address cycle followed by many data read/write cycles terminated by the bus master (similar to Block Transfer, but of unlimited length).