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IBM Personal Computer AT (5170)

5170 · 1984–1987 · desktop

Specifications

Cpu: Intel 80286, 6 MHz
Ram: max: 16 MB via the 286's 24-bit address bus, though most period expansion cards topped out well below that · base: 256 KB (512 KB on some configurations)
Ports: Keyboard port (5-pin DIN) · 8 internal ISA expansion slots (6 16-bit, 2 8-bit) · Parallel (Centronics) via add-in card · Serial (RS-232) via add-in card
Display: IBM Enhanced Graphics Adapter (EGA, optional) up to 640x350 in 16 colors, or CGA/MDA cards from earlier PC models, all sold separately
Storage: base: 20 MB hard drive plus one 1.2 MB 5.25" floppy drive · options: 30 MB hard drive · Second 1.2 MB floppy drive
Os Support: latest: PC DOS 6.22 / early Windows 3.x ran, though most owners kept the AT on DOS given its real-mode era chipset · shipped: PC DOS 3.0
Release Price: $5,795 (base configuration with 20 MB hard drive)

Upgrade paths

RAM

Up to 16 MB addressable by the 80286, though period expansion cards typically maxed out around 2-4 MB · The 286's protected mode allowed more RAM than the 5150/5160, but DOS software of the era could rarely use more than 640 KB directly.

~$500-$1,000 for a period memory expansion card

MODERATE

storage

30 MB internal hard drive, or third-party MFM/RLL controller cards for larger drives · Standard ISA hard disk controller interface, widely supported by third-party cards.

~$1,000+ for a period drive kit

MODERATE

CPU

Locked to the socketed 80286 (6 or 8 MHz depending on revision) · No official IBM upgrade path beyond the socketed 286; some hobbyists later fitted NEC V-series or faster 286 replacements.

HARD