The simplest configuration has only 16K on-board RAM and uses an audio cassette to load and save data—the floppy drive was optional, and a hard drive was not supported.
A basic system for home use attaches to an audio tape cassette player and a television set (that means no floppy drives or video monitor) and sold for approximately $1,565. PC-DOS, the operating system, was not available on cassette, so this basic system is only capable of running the Microsoft BASIC programming language, which is built-in and included with every PC.
A more typical system for home or school with a memory of 64K bytes, a single diskette drive and its own display, was priced around $3,000.
An expanded system for business with color graphics, two diskette drives, and a printer cost about $4,500.
Five internal ISA expansion slots on the motherboard provide the ability to add additional memory and other capabllities, although one slot is usually occupied by the video card, and another by the optional floppy drive controller. A third slot typically has an RS-232 serial port card installed. A modem card for dialing-up remote computer systems became a popular option as well.
Although the original IBM 5150 "PC" supported only 64K of RAM memory on the motherboard, later versions used higher capacity memory chips, allowing up to 256K onboard - up to 640K with internal expansion cards.