The IBM PC/XT 286, Model 5162, was an 6MHz 286 AT-class PC made by IBM from late 1986 to early 1987. It was basically an AT redesigned to fit inside an XT-class chassis, and it was made to compete whith the low-budget AT-clones which were increasing in popularity at the time. Some sources claim that it was made with the sole purpose of emptying the stock of XT chassises to prepare for the production for the PS/2. Due to the short production span, the PC/XT 286 is by many considered to be the rarest of the IBM PC desktops. The number of produced units is estimated to be somewhere between 20 000 and 50 000 units, and working systems in good condition often sells for more than $100 USD on common webmarkets. Despite it's name, it has very little in common with the actual [wiki="IBM_PC_XT_(5160)"]IBM PC/XT[/wiki].
It shares most of the features of the [wiki="IBM_PC_AT_(5170)"]IBM PC/AT[/wiki] with a few differences:
- The motherboard is smaller (to fit in an XT chassis), and has a different layout.
- The CMOS battery is a CR-P2 battery in a proper battery holder, which can be operated from the outside of the chassis.
- It uses a Zero-waitstate RAM interface compared to the AT which uses one-waitstate RAM interface.
- The 287 runs at 4.77MHz rather than at 6MHz.
- The later 512KB of RAM is placed on SIMM memory modules rather than on expansion cards.
- It doesn't have any tuning capacitor for the CGA adapter's composite out color-burst signal.
- The BIOS is different, but it uses much code taken directly from the second 6MHz PC/AT BIOS from 06/10/85.
- It has three 8-bit-only slots instead of just two.
- No sockets are present for additional BIOS ROM chips. Instead; The main BIOS is mirrored in the E000 segment (where the additional BIOS ROM chips should have been mapped).
- The ISA Bus is fully terminated.