The Atari PC-5 is really not an Atari computer anymore other than by branding. The proprietary Atari motherboard has been replaced by an American Megatrends (AMI) 386XT Series-4 board. The machine runs on a 80386DX at 16 or 20MHz, and there is a socket for a 80387 Co-processor. The CPU can also be upgraded to a 386DX-25Mhz. The machine has a Seagate 66MByte hard drive, a 1.2MByte 5.25" or 1.44MByte 3.5" floppy drive and a Western Digital VGA Plus 16 VGA graphcis adapter.
Intel 80386 CPU
The Intel 80386, later renamed to i386, is a 32-bit microprocessor introduced in 1985. It was the 32-bit extension of the 80286 architecture. The instruction set, programming model and binary encoding are common throughout all 32-bit x86 processors, which is now referred to as the x86, or i386-architecture.
The 80386 can correctly execute code intended for the earlier 16-bit processors such as the 8086 and the 80286. Production of the 80386 processors was stopped in 2007. Even though the CPU was no longer used in PCs, it was still used in many embedded systems.