IBM PC/XT Images

External Pics

Here's a nice picture of the 5160 in action. This one has the IBM 5153 RGB colour monitor.You can tell a 5160 over a 5150 by the single floppy drive and hard drive taking the right-hand bay, as well as the badge denoting "XT" (see below). Aside from those exterior changes, from the front there's no difference.

more external pics to come shortly...

Monitors

Here's the IBM 5151 monochrome monitor, which was the cheaper option for new buyers of the IBM PC and XT. The same identical monitor was sold with both these computers, and was designed to work with the IBM Monochrome Display Adapter (MDA), which produced no graphics modes, but had a very clear 80x25 text mode. The monitor can support a resolution of 720x350 at 50 Hz if used with a graphics card.

It has a 12" (diagonal) display area, with constrast and brightness controls on the front.

It uses digital TTL (transistor-transister logic) signalling from the PC via a 9-pin DSUB male connector. It is powered from the PC itself via the female AC ("kettle lead") socket on the back of the PC power supply, so there is no power switch on the monitor.

Drives and Controllers

DOS 2.0, introduced with the XT, was the first version to support hard drives. Since the motherboard's BIOS doesn't support hard drives, the original full-length disk controller cards supplied with the XT contain their own 8 KB BIOS ROM. These types of ROMs would later be referred to as BIOS extensions, or BIOS expansions.

The standard 10 MB hard disk drive supplied with the XT was the Seagate ST-412. This wasn't Seagate's first drive - the ST-506 preceded it, having a capacity of 5 MB. Both were the first drives to use MFM encoding. The ST-412 had 8 read/write heads, 4 platters, spun at 3,600 rpm and weighed 2.1 kg. Bought separately, it would have cost £263 in 1983. Typical for its time, the average seek time was 28ms with data transfers up to 5 Mbps. These drives had a MTBF (Mean Time Before Failure) of 150,000 hours (that's 17 years if continuously running).

You can tell if your drive was supplied by IBM rather than fitted later by a third-party because the original drives have "IBM" embossed in the top-left corner of the black fascia.

The hard disk controller card for the XT is manufactured by Xebec, with the BIOS extension code authored by IBM. Several versions of hard disk controller were provided with the XT, depending on the year. The first had model number "IBM 1501492". The second was "IBM 6135983".

When 20 MB hard disks arrived around 1986, IBM offered the "20MB Fixed Disk Drive Adapter", which was a later controller card that supported the larger capacity. This had model number "IBM 62X0775" or "IBM 62X0786".

All were full-length cards, i.e. they used the entire length of the case from front to back. The front of the PC and XT cases have special plastic guide rails that give more support for full-length cards.