An original Apple 1 motherboard from 1976 sold at auction today for $374,500, while a hand-written note from Steve Jobs's days at Atari went for $27,500, according to Sotheby's.

An original Apple 1 motherboard from 1976 sold at auction today for $374,500, while a hand-written note from Steve Jobs's days at Atari went for $27,500, according to Sotheby's.

The auction house originally expected the Apple 1 motherboard to sell for between $120,000-$180,000 and the memo .

The Apple 1 lot includes: a circuit board with four rows A-D and columns 1-18; a MOS Technologies 6502 microprocessor, labeled MCS 6502 3776; a video terminal; keyboard interface; 8K bytes of RAM in 16-pin 4K memory chips; 4 power supplies including 3 capacitors; firmware in PROMS (A1, A2); low-profile sockets on all integrated circuits; breadboard; heatsink; expansion connectors; and a cassette board connector, according to the Sotheby's description.

The buyer will also get various manuals that go along with the motherboard, including one with the original Apple Computer Co. logo on the wrapper, though they have all endured a bit of wear and tear.

"An exceptionally rare, working example with original Apple cassette interface, operation manuals and a rare BASIC Users' Manual. It is thought that fewer than 50 Apple I Computers survive, with only six known to be in working conditions," Sotheby's said in its item description.

The Apple 1 motherboard dates back to 1976, when Steve Jobs and Steve Wozniak convinced Paul Terrell to sell the devices in his Byte Shop chain of computer stores. Terrell ordered 50 Apple 1 motherboards at $500 each, provided Jobs and Wozniak deliver them pre-assembled rather than as DIY kits. The duo soon moved on to more modern computing endeavors, but the Apple 1 represents that start of the Macs we know today.

In Nov. 2010, an Apple fan for an Apple-1 when it went up for auction at Christie's in London.

The Atari listing, meanwhile, features a four-page, handwritten manuscript from Jobs that he wrote in 1974 for his then-supervisor Stephen Bristow. According to Sotheby's, Jobs details a way "to improve the functionality and fun of World Cup, a coin arcade-game with four simple buttons and an evolution from Atari's Pong game." That includes circuit diagrams, as well as designs for paddles and alignment of players defending a soccer goal.