IBM Personal Computer XT
The IBM Personal Computer XT (Type 5160) or simply XT (for e X tended T echnology), introduced on March 8, 1983, is a minor further development of the IBM PC . Both devices, PC and PC XT, are often grouped under the abbreviation PC / XT and thus differentiated from the technically significantly changed successor model, the IBM PC AT .
In contrast to the original PC, it has a hard disk ( MFM ) with a capacity of 10 MB , a correspondingly larger power supply , a ST-506 compatible hard disk controllers , and more slots for memory and XT bus - expansion cards on the motherboard . It was also delivered with the newer PC-DOS 2.0, which for the first time supported the subdirectories that are almost indispensable when working with hard drives .
A late model of the PC XT , the PC XT 286 ( type 5162 ) was only introduced on September 2, 1986. Instead of the 8088 - it has an 80286 - CPU , which made it a cheaper alternative to the IBM PC AT , which has been available since 1984 . Although the 80286 CPU in the XT 286 was only clocked at 6 MHz instead of 8 MHz in the PC AT , it achieves a higher speed due to its faster working memory. And it also has the 5.25 ″ floppy disk drive with a storage capacity of 1.2 Mbytes and half the height (1.75 ″) that was already introduced in the PC AT .
IBM also manufactured the EMR (ElectroMagnetically Resistant) XT for military and diplomatic applications. It was secured by careful shielding measures against "eavesdropping" on electromagnetic radiation in accordance with the American TEMPEST standard.
The PCs XT and XT 286 can be expanded with the Expansion Unit Model 5161 by an identical housing with space for additional drives and expansion cards. For this purpose, a card with driver modules was inserted into the XT, which connected the bus of the XT with that of the expansion unit via a cable. The same option was available for the original PC.