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PC - Model 5150

The computer which caused the death of CP/M computers.

In the early part of 1980, IBM decided to create a microcomputer (up to this date, IBM produced only mini and mainframes). They didn't really know that they wanted and they didn't think for one second that producing microcomputer was a profitable business (who would have thought!)!
After hesitation between the Intel 8086 (16 bit) and the Motorola MC68000, they decided to use the Intel 8088 (8 - 16 bit) processor, as the two other ones were considered too powerful! Then they asked to Digital Research (the creators of CP/M) to create an operating system for their new computer, as DR was not very interested, they then asked a small company (famous for its BASIC Programming Language) to write the operating system: Microsoft.
Microsoft wasn't capable of doing it, Bill Gates bought the rights to a small, hacked OS written by a small company called Seattle Computer Products: QDOS (which reportedly stood for "Quick and Dirty Operating System", which itself bears a striking resemblance to CP/M) which became PC-DOS and then later MS-DOS!
In fact, when it was launched, three operating systems could run on the IBM-PC: PC-DOS, CPM-86, but also the UCSD D-PASCAL system.

The original IBM PC wasn't very powerful (and was certainly less powerful than lot of 8 bit computers at the time). The very first PC’s had only 16 KB RAM and no floppy disk units, they used cassettes to load & store programs (notice that the commands to handle the cassette drives were present in the operating system all the way up to MS-DOS 5!). In fact, units could also be purchased from IBM with drives and more RAM. Only the lowest cost version had no drives included (this is exactly how Apple and the other manufacturers did it as well).

The model 5150 was actually a success due to name and fame of IBM, high quality construction (especially the keyboard and monitor), great expandability and IBM's decision to publish complete technical specs. The IBM PC Technical manual included circuit diagrams and the full source code for the BIOS! The PC 5150 became a standard and IBM ran the business computer market up to the end of the 80's.

Now, we can consider that about 90% of the microcomputers are PC compatibles and run under MS-DOS or Windows (At the beginning, Windows was just a graphic interface for MS-DOS, but that’s another story).

Although the IBM PC XT was launched in 1983, IBM continued production of both units, in various configurations, for several years. The model types were followed by a xx version number, i.e. 5150-xx, where the xx represented the included options (amount of RAM, single or dual floppy disk drive, etc.).

Jeffrey H. Ingber reports that when these computers (PC and XT) were initially sold, they were built-to-order computers (sounds like Gateway or Dell, doesn’t it?). Retail outlets would carry the factory products, which consisted of a boxed computer with basic components such as the motherboard, power supply, floppies & floppy drives, etc. There was no official base model configurations for the PC and XT.
Customers had a choice of RAM, display, serial ports, etc. that they could have installed on-site before the computer went home.
One could not purchase a "new" PC/XT and run it out of the box becuase it was incomplete without additional configuration.

The PC was available with either CGA or MDA (on an MPA card). The CGA adapter actually has an RCA composite output to hook it up to your TV if you did not want the CGA monitor. The output quality was PERFECT!

Another notable great feature of the PC line was the expansion base: it added additional (I think it was eight) 8-bit slots in an external enclosure.