In 1988 Atari manufactured the Atari PC-3, a computer very much like the Atari PC-1 and the PC-2, but with a new case, a 5.25 or 3.5" Floppy Disk Drive and a Seagate 30MByte Hard drive.

The machine has 640KByte RAM and Onboard EGA Graphics, using the NSI Logic EVC315-S in early machines and ST-Microelectronics EGA in later revisions.

Atari bundled the follwing software with the PC-3

• Micrsoft MS-DOS 3.21
• GW Basic 3.2
• GEM Desktop EGA 2.2
• GEM Paint 2.0
• GEM Write 1.01

As in the earlier models, Atari continued to use Atari components in their PC-line, and this machine has the Atari STM1 Mouse (but relabeled as PCM1) connected to an Atari mouse port located on the side of the case where also the XT keyboard connector is.

The Intel 8088 microprocessor is a variant of the Intel 8086. The 8088 has an 8-bit external bus instead of the 16-bit bus that the 8086 has. The 16-bit registers and the 1MByte address range are unchanged, however. The 8086 and the 8088 have the same execution unit (EU), only the Bus Interface Unit (BIU) differs.

The original IBM PC architecture is based on the Intel 8088. The CPU runs at 5 to 16 MHz, has a 20-bit address bus and can work together with the 8087 Co-Processor. The 8088 was launched in 1979. The 8088 is compatible with the Intel 8085.