IBM PC/XT-286

Introduction

Launched in 1986, the IBM Personal Computer XT Model 286 (Model 5162) was designed to sit between the XT and AT, and retailed for $3,395.

Like the Model 5170, it used the same 6 MHz 80286 microprocessor, and came as standard with 640 KB of RAM, a 1.2 MB floppy disk drive, and a 20 MB hard disk. It used the XT system unit case size which did cause problems when trying to use some taller expansion cards designed for the AT case.

Despite it being marketed as a lower-tier model compared to the Model 5170, it actually ran faster than its pricier big brother, due to having zero wait state memory - this meant around a 32% improvement over the original 6 MHz Model 5170 with its 1WS, and only marginally slower than the 8 MHz Model 5170. The use of "XT" in the model name was simply a marketing one - this was a full AT-class machine.

Early versions used the slower 20 MB hard disk that was shipped with the XT.

It was discontinued in the Spring of 1987 at the same time as the Model 5160 XT.

Model Variants

The following models were available to purchase:-

Model 5162, 640 KB RAM, single 1.2 MB floppy drive, no display adapter or monitor = $3,395 USD.

The price point for the XT-286 at $3,395 with no display adapter and monitor compared favourably to the 8 MHz Model 5170 available at the same time which had a list price of $5,295. The Model 5160 XT at the time had a list price of $2,300 for the 8088 system with 20 MB hard disk, 640 KB of RAM and no display adapter or monitor.

Retailers did provide discounts on IBM's list price, so you could typically get a Model 5162 with a monochrome display adapter and monitor for as low as $2,800.

Compared to compatible systems from other vendors, choosing IBM was still a costly choice. AST's Premium/286 listed for $3,190 and offered 10 MHz 80286 performance with zero wait states.

Supplied Software

Just as with the original IBM PC/XT and IBM PC/AT, no software was supplied with the XT Model 286.

 

Expansion / Compatibility

The XT-286 came with 8 expansion slots, of which five were 16-bit and three were 8-bit. Only one of the 8-bit slots could support a full-length expansion card, with the other two only catering for shorter cards no longer than about 5".

There was only one revision of the XT-286 motherboard.

It also came with a 25-pin parallel port and a 25-pin serial port.

 

BIOS / RTC

The XT-286 came with a battery-powered realtime clock/calendar.

 

Monitors / Graphics

The XT-286 was typically sold with the additional cost options of IBM Color Graphics Adapter and Model 5153 Color Monitor.

 

Keyboard / Mouse

The XT-286 came with the IBM Enhanced AT keyboard.

 

 

Floppy Disk Drives

The XT-286 came as standard with a single 5.25" 1.2 MB DS/HD floppy disk drive, which communicated with the motherboard via a combined 16-bit floppy/hard disk controller card.

Installing a 3.5" DS/HD 1.44 MB floppy disk drive was as easy as connecting it up and running SETUP to configure it.

 

Hard Disks

The XT-286 came as standard with a 20 MB hard disk. To support this, the power supply fitted to the machine was a 150-watt 120V-240V linear PSU, slightly below the XT's 157W.

Early machines got the slower hard disk sold with the XT, but this was soon replaced with a 40ms one offering similar performance to the 20 MB CMI-20 hard disk available for the AT. The drive defaulted to a 2:1 interleave which gave it a 33% boost in performance over the original 1985 AT hard disk's 3:1 interleave.

 

Memory

The maximum amount of memory supported by the IBM XT-286 was 16 MB. This

From the factory the 640 KB of 150ns memory was installed in two banks. Two 30-pin SIMM slots made up the first bank of 0-512 KB (256 KB in each slot), with a second bank making up the 512 KB-640 KB memory area. The latter comprised six DRAM chips near the motherboard's power connector. This 128 KB could be disabled with a jumper on pins 2 and 3 of J10.

It is not known whether the SIMM slots supported larger SIMM modules than 256 KB. The usual method of expanding memory in 1986 was to purchase memory expansion cards that fitted into one of the ISA expansion slots.

 

CPU

The Model 5162 came with the Intel 80286 microprocessor, which ran at 6 MHz. This was the same as the original IBM PC/AT Model 5170.

 

Operating System

The IBM PC Model 5162 is capable of running DOS versions from 1.0 right up to 6.22 - the default version on release was IBM PC DOS 3.20.

 

FAQ

Q:
A:

 

Physical Attributes

Item	Dimensions (mm)	Weight (kg)
System unit	19.6" (w) x 16.1" (d) x 5.5" (h)	21 lbs (no disk drives), 25 lbs (one drive), 28 lbs (two drives)
Keyboard unit	20" (w) x 8" (d) x 2" (h)	6 lbs
Matrix printer	16" (w) x 15" (d) x 4" (h)	12.5 lbs
Monochrome display	15" (w) x 14" (d) x 11" (h)	17 lbs
Colour display	372(w) x 365(d) x 330(h)	11.6