Tomado de Forbes.com – por Zorro
IBM (NYSE: IBM ) introduced the PC, or Personal Computer, on August 12, 1981. At the time of its introduction, most computers were still processing 8
bits of information per clock cycle. IBM revolutionized the industry by hitting the market with a computer based on the Intel 8088 processor, which was compatible
with 8-bit computers but processed information internally at 16-bits per clock cycle. The PC featured an expandable design, known as «open architecture», which
made it possible for users to add features to their machines without replacing the whole computer.
The original IBM Personal Computer (PC) (Model 5150) came standard with 16k of RAM (9x16kbit chips, soldered), expandable to 64k of RAM on the system
board (3 more banks of sockets) and 540k total (not 640, due to a hardware bug), a green-on-black slow-phosphor TTL Monochrome Monitor (Model 5151)
which plugged into the female AC port on the a 63.5 Watt black power supply (and so needed no power switch of its own), a Monochrome Graphics Adapter with
25-pin female parallel printer port, 25-pin Serial Port with 25-pin male interface (possibly first in the industry), 2 full-height drive bays (with no screw holes for
half-height drives), 1 full-height floppy diskette drive capable of using single- and double-sided, single- and double-density disks with 8 or 9 512-byte soft sectors on
40 Tracks at 48 Tracks Per Inch (a capacity range of 80-360k), and IBM PC-DOS v1.1 (limited to 8 tracks or 320k) and v2.0 (the 1.0 version was too buggy to
use effectively and was replaced quickly). A second parallel port, second 360k floppy diskette drive, Color Graphics Adapter (without Printer Port), and color
monitor (Model 5152) were optional. The second version, which carried the same model number but had five screws holding the case to the chassis instead of 2,
came standard with 64k (9x64kbit chips, soldered) of RAM, expandable to 256k (also 3 more banks) on the system board and 540k total. Both carried the
nameplate ‘IBM Personal Computer’. Because of its expandability, third-party manufacturers quickly started selling hard drives that could be used to add mass
storage capability to the IBM PC.
On March 8, 1983, IBM released the Personal Computer XT, short for eXtended Technology, or PC/XT, or just XT. It came equipped with a 10 megabyte MFM
Full-Height Hard Disk Drive with 306 Cylinders, 4 Heads, and 17 512-byte Sectors, was expandable to 640k of RAM on the Motherboard, and came with
MS-DOS v2.1, which supported directories and subdirectories. It had one or two half-height 5 1/4 inch floppy drives, and was later available with a 20 megabyte
Half-Height Hard Disk Drive with 615 Cylinders, the Seagate ST-225, interleaved at 3:1. It carried the nameplate ‘IBM Personal Computer XT’.« The expansion
bus also contained eight slots instead of the original five. This gave users greater flexibility in the addition of peripherals to their machines. Because this machine was
so popular, many manufacturers began copying IBM’s design. These copies were referred to as ‘clones.’
Since the introduction of the XT, there has been an explosion in the PC industry. This was largely made possible by the open architecture of the IBM PC and XT.
Many 286,386, and 486 computers have been built with the same slot-width as the IBM XT, resulting in the term ISA, or Industry Standard Architecture.
- Release Date: Mar 8, 1983
- Original Price: $7,545.00 (according to IBM price list)
- Processor Speed: 4.77 mhz non-Turbo model, 8+ mhz Turbo (8086 or 8088 CPU)
- Memory: 64k to 640k of RAM, 40-64k BASIC ROM on true IBM models.
- Graphics: Varied. 80 x 25 text mode standard.
- Input/Output Devices: Too many to list. Basically, you want it, you can get it.
- Drives: Built-in support for 360k and 160k 5.25» drives and 720k 3.5« drives. Also supports most hard drives that you can find 8-bit controllers for. Originally had 10MB or 20MB Winchester drives.