IBM 5150

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IBM 5150.jpg
Manufacturer: International Business Machines
Year Introduced: 1981
Word Size: 16 bit

The IBM 5150 was IBM's entry into the personal computer marketplace; the IBM PC. It was introduced in stores on 1981-08-12.

The original configuration had a motherboard with 16K built in, designed for up to 64KB of RAM, and a cassette tape drive, but could be expanded to include a diskette drive, and a hard disk.

At the beginning they were advertised for around $1,600 for a unit with just 16KB of RAM and a keyboard[1]. Retail would be around $1,000 though[2], or maybe more likely in the $1,300 - $1,400 range[3]).

In practice you would add a at least a video adapter, probably some RAM, and a floppy disk drive. Then the price would be quite different. Back then, both types of disk drives were of the 5 1/4" full height form factor, single sided or double sided.

IBM made the PC an open standard, publishing not only schematics, but also including a BIOS listing in the technical reference. When people wished to build clones of the IBM PC, IBM would license them for a 5% royalty fee, which not only made the PC a popular platform to clone, but also with the available schematics, allowed for everyone to be pin compatible with the ISA slots, creating a thriving hardware expansion business.

IBM PC Motherboard

The IBM PC included Microsoft BASIC in ROM, called Cassette Basic, which allowed the PC to function like many of the computers of the time with a simple ROM BASIC. With the addition of a disk drive, OS options included CP/M-86 and MS-DOS 1.0, and later MS-DOS 1.1 at the time of sale. DOS included a simple version of BASIC, known as disk BASIC, and a graphics version known as Advanced BASIC (BASICA.COM)

The IBM PC, also established the 8 bit expansion slot, or ISA bus standard as it was later called.

The PC started the IBM PC line; it was replaced by the wildly popular IBM XT, adding 3 more slots, and support for more memory on the motherboard ( 64k, expandable to 256k ).

The picture shows 5 ROMS, one was the ROM BIOS, and the other 4 were cassette BASIC.

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