The IBM PC Model 5150 was originally introduced in August 1981. Price at Introduction: $1,995.00. Standard Memory: 16k bytes . Built at a new, automated factory in Boca Raton, Fl. Initially introduced with a massive (insert many smilies here!) 16k of memory, (expandable to 64k on the main board) monochrome (green) display capable of only rudimentary line-character graphics, a cassette I/O port for program storage, and a price tag just under $2000.00US, this machine set the bar for the second age of the personal computer.
Comments from James Willigen: "Yes, the creature from Boca! The
beginning of the end for the first age of the personal computer.
Initially introduced with a massive (insert many smilies here!) 16k of memory, (expandable to 64k on the main board) monochrome (green) display capable of only rudimentary line-character graphics, a cassette I/O port for program storage, and a price tag just under $2000.00US, this machine set the bar for the second age of the personal computer.
The basic machine had no I/O capability beyond its keyboard, display, and cassette data port, but it did seem to have two things going for it... You did not have to build it, and it had a name tag - I.B.M.
However, it did come with some baggage associated with its parentage... Add-on items (memory, floppy drives, etc.) cost a lot! And IBM did not want to tell you anything about the machine.
The prime example of this was the 40 pin socket located next to the 8088 microprocessor. While it was generally accepted that this socket was destined for the 8087 math co-processor that Intel had developed as a companion to the 8086/8088 microprocessors, IBM went out of their way to deny this and warn (in no uncertain terms) that should you ever plug something into this socket it would bring death and destruction to your poor unsuspecting computer. (not to mention that it would void your warranty)
Perhaps its saving grace was that the specification for the expansion bus was made available and this allowed the rapid development of third-party add-on cards that were compatable with the unit. Once that began, the march to fully compatable 'clones' was inevitable. (in a rapid repeat of the history that surrounded the 'Altair') "
128 KB memory
2 floppy disk drives (360K)
Built-in Basic Compiler
6 Slots for plug in cards
Cards for Connections for Parallel printer, modem, joystick
Other manufacturers produce compatible cards
|IBM PC (display under construction) |
IBM announced its entry into the personal computer market in 1980>. Standard models had 64K of memory and one or two drives for floppy disks (A,B) of 360K each. Memory capacity could be increased to 640K. Memory addresses above 640K were dedicated to special functions, as the display. The standard, black and white display tube, as shown, required about yy K for its 640 by 480 pixel display. Standard characters of 8 by 12 pixels allowed displaying 40 lines of 80 characters each. Later models provided a 10 Megabyte hard disk (C), replacing one of the floppy drives.
|Two aspects of the
IBM PC marketing strategy were unusual:|
The operating system was produced by an independent vendor, Microsoft, rather than developed, or purchased and adapted, for exclusive use by IBM.
The interface specifications were open, and allowed other manufacturers to make compatible hardware and software components, without the risk of design changes making their products obsolete. These decisions created a market for compatible and competing cards and software, and broadened the appeal of the PC. Later hardware attached to PCs included communication gear, the mouse, and an ever-increasing complement of storage and input-output hardware. Once these components were available, competing companies making alternate, but compatible, PCs were assured of being able to buy an operating system, the required plug-in parts, and application software, greatly lowering the cost of entering the PC market.
Keeping the base PC architecture compatible has also led to
complexities. When memory capability had to be increased a logical
hole had to be left between 640K and 1M. Limits in disk addressing
also had to be adjusted periodically, so that high-capacity disk units
may not work well on older models.
The particular PC partially shown here was manufactured in 1984 and used to control a mass spectrometer at Stanford Chemistry until early 1999.