IBM 5150

Desktop, 1981

The 1981 IBM Personal Computer. This one boots os8088 from a 360K floppy onto a green IBM 5151, carries the desktop across to a second monitor in CGA, and plays video with its sound from the PC speaker.

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IBM 5150, on the bench

IBM 5150 · IBM 5151 display · Model F keyboard

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Video: IBM 5150, PC speakerVideo by AcornsN64.

A green phosphor monitor filling the frame. The os8088 desktop carries a Bounce window, a Note Pad typed with the machine's card list, an About os8088 box reading Hercules 720x348, a Clock at 00:11:45, a Task Manager reading CPU 3% and RAM 150K of 640K, a Minesweeper board and a Disk window listing MINES.O88, HELLO.O88, NOTEPAD.O88 and RECORDER.O88. — IBM 5150, screen

A desk holding an IBM 5150 with a lit green IBM 5151 monitor on top of it showing the os8088 desktop, and beside it a Packard Bell case with an IBM 5153 color monitor on top whose screen is completely dark. A cassette recorder, a printer and other machines fill the rest of the bench. — IBM 5150, on the bench

CPU: 8088, 4.77MHz
display cards: Hercules GB101, CGA
monitors: IBM 5151, IBM 5153
boot drive: Tandon, 360K
hard disk: Seagate ST-225, 20MB
sound: PC speaker, 6500Hz

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History, photos & source references

An IBM 5150 Personal Computer with its Model F keyboard in front and an IBM 5151 monochrome monitor sitting on top of the case. The green phosphor screen shows the os8088 desktop: a menu bar, several overlapping windows and a dock along the bottom. — An IBM 5150 with a Model F keyboard and an IBM 5151 monitor, running os8088.

Two display cards, and os8088 takes the Hercules

720x348 on a green 5151, off one 360K floppy.

Both cards at once, and a soundtrack with no sound card

Hercules on the 5151, CGA on the 5153, one desktop.

Here both display cards are in use, joined into one desktop across the two monitors. There is no sound card. The Video Player plays the soundtrack through the PC speaker, switching it on and off faster than the cone can settle, and that alone takes about 70% of the processor. Drawing frames and reading ahead off the hard disk into 640K of RAM share the rest; a frame that is not finished in time is cut.

An IBM 5150 with an IBM 5151 monitor on top, its green screen showing os8088 with a Paint window open. Written by hand on the canvas in large black strokes: Pc SPK, 6500Hz, 4.77Mhz. A hand rests on a mouse on a blue pad in front, and to the right an IBM 5153 color monitor on a beige Packard Bell case is dark. — The 5151 in Hercules, with the setup written on Paint's canvas by hand. Still from the video by AcornsN64.

The IBM 5150 and both of its monitors side by side. The green 5151 on the left still shows the Paint window reading Pc SPK, 6500Hz, 4.77Mhz. The 5153 on the right, on a Packard Bell case, shows a Disk window titled MEDIA, reading Drive C: 14 files and listing CGAWOLF2.V88, ELYSIUM.MOD, GUIDE.TEX, MIKUMIKU.V88 and OS8088.GIF. — A Disk window moved across to the 5153, open on the MEDIA folder with `MIKUMIKU.V88` in it. Still from the video by AcornsN64.

The IBM 5153 color monitor filling the right of the frame, playing a video full screen in CGA's cyan, magenta, black and white: a cartoon figure in sunglasses on the left and the words I'M THINKING on the right. The 5151 to its left is blank, and a mouse and keyboard sit in front. — The video full screen on the 5153, in CGA's four colors. Still from the video by AcornsN64.

An IBM designed in a year, from parts off the shelf

The launch price bought no disk drive and no monitor.

Although the 5150 was not IBM's first microcomputer (the 5100 took that honor in 1975, at up to $20,000), it was the first IBM sold through retail stores, and it was assembled from other companies' parts: Intel's processor, Microsoft's BASIC and DOS, an Epson printer under an IBM label. IBM's own account gives 40 days for the motherboard design and four months to a working prototype. The business plan forecast 220,000 machines in three years. In 1983 alone IBM sold more than 750,000.

BYTE's review of January 1982 priced a usable machine -- 48K, the color adapter, one floppy drive and DOS -- at $2,575, against $2,175 for a comparable Apple II Plus and $1,995 for a TRS-80 Model III, and still called it "easily the best-designed microcomputer to date".

What IBM did not offer was a hard disk. The power supply could not start the drives of the day, DOS 1.0 and 1.1 had no support for one, and the first two BIOS revisions ignore the ROM on a controller card and count no more than 544KB of memory. The third, dated 10/27/82, lifts both limits. Neither of IBM's display cards gave everything either: the monochrome adapter drew sharp text and no graphics, the color adapter drew graphics at 200 lines. The Hercules card of 1982, which Van Suwannukul built to set Thai script for his doctoral thesis, put bit-mapped graphics on the monochrome display, and half a million had sold by 1985.

introduced: August 12, 1981
price at launch: $1,565
RAM: 16KB as shipped, 640KB with cards
slots: five, 8-bit
floppy drives at launch: up to two, 160KB each
power supply: 63.5W

Most of this one is newer than 1981

The parts in the photographs, and when each arrived.

Part	What it is
IBM 5151	The 11.5-inch green monitor for the monochrome adapter: 720 by 350 at 50Hz. It has no power switch and no mains lead of its own; it plugs into the back of the system unit and comes on with it.
IBM 5153	IBM's 13-inch color monitor, announced in February 1983, about eighteen months after the color adapter it was built for. A circuit inside it turns dark yellow into brown, which is why CGA has a brown, and why EGA and VGA kept one.
Hercules GB101	The 1983 revision of the Hercules card. It added a software switch that holds the card to the first of its two graphics pages until a program asks for the second, and that is what lets it share a PC with a color adapter.
Tandon TM100-2	The double-sided 5.25-inch drive IBM fitted, 40 tracks a side at 300rpm. The 360K format arrived with DOS 2.0 in 1983; the 1981 machine had single-sided drives.
Seagate ST-225	A half-height hard disk, first shipped in October 1984: 615 cylinders, four heads, 65ms average access. It can draw 2.2A from the 12V line as it starts, where the 5150's supply is rated for 2A, and the pairing is reported to work anyway. Its heads do not park themselves.
Keyboard	83 keys on the Model F mechanism, a buckling spring over a capacitive board. BYTE, January 1982: "bar none, the best keyboard on any microcomputer", with one complaint about where the shift keys sit.

Sources

The IBM PC IBM Heritage. The announcement, the launch price, the 40-day motherboard.
IBM Personal Computer Wikipedia. The 5100, the retail channel, slots, memory and sales figures.
A Closer Look at the IBM Personal Computer Gregg Williams, BYTE, January 1982, page 36. The verdict, the keyboard and the price comparison.
The IBM Personal Computer: First Impressions Phil Lemmons, BYTE, October 1981. The launch price list.
IBM 5150 BIOS revisions minuszerodegrees.net. The three BIOS dates and what the first two cannot do; the same site's pages on the power supply and hard disks.
Hercules Graphics Card GB101 Owner's Manual Hercules Computer Technology, 1984. The two graphics pages and the software switch.
Hercules Graphics Card Wikipedia. The Thai thesis, the revisions and the sales figure.
IBM Monochrome Display IBM Hardware Reference Library. The 5151.
IBM Color Display IBM Hardware Reference Library. The 5153.
Color Graphics Adapter Wikipedia. The 5153's brown.
TM100-1, TM100-2 Product Specification Tandon, 1984. The floppy drive.
ST225 OEM Manual Seagate, October 1985. The hard disk's geometry, access time and power; its first shipment date is from the 1985 Disk/Trend Report.

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