Macintosh Processor Upgrade Card

The generically named Macintosh Processor Upgrade Card was a central processing unit

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

 upgrade card sold by Apple Computer

Apple Computer

Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...

, designed for many 68040

68040

68040 may refer to:* The Motorola 68040 computer processor chip* The Zip Code for the town of Malmo, Nebraska...

-powered LC

Macintosh LC

The Macintosh LC was Apple Computer's product family of low-end consumer Macintosh personal computers in the early 1990s. The original Macintosh LC was released in 1990 and was the first affordable color-capable Macintosh. Due to its affordability and Apple II compatibility the LC was adopted...

 and Performa model Macintoshes. The card contains a PowerPC 601 CPU and plugs into the 68040 CPU socket of the upgraded machine. The Processor upgrade card required the original CPU be plugged back into the card itself, and gave the machine the ability to run in its original 68040 configuration, or through the use of a software configuration utility allowed booting as a PowerPC 601 computer running at twice the original speed in MHz (50 MHz or 66 MHz) with 32 KB of L1 Cache, 256 KB of L2 Cache and a PowerPC Floating Point Unit

Floating point unit

A floating-point unit is a part of a computer system specially designed to carry out operations on floating point numbers. Typical operations are addition, subtraction, multiplication, division, and square root...

 available to software. The Macintosh Processor Upgrade requires and shipped with Macintosh System

Mac OS

Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...

 7.5.

Apple described the Macintosh Processor Upgrade Card as giving a performance increase of "two to four times" for general purposes, or "up to 10 times" for floating point intensive programs.

While the Macintosh Processor Upgrade did not plug into the LC Processor Direct Slot

Processor Direct Slot

Processor Direct Slot or PDS introduced by Apple Computer, in several of their Macintosh models, provided a limited measure of hardware expandibility, without going to the expense of providing full-fledged bus expansion slots.Typically, a machine would feature multiple bus expansions slots, if any...

, due to power used and the space taken by the upgrade, LC PDS cards could not be fitted while the card was installed. This limited the usefulness of the Processor Upgrade Card, as internal ethernet, Apple IIe compatibility, video cards and other LC PDS expansion options must be removed.

DayStar Digital

DayStar Digital

DayStar Digital, Inc., was founded in 1983 by Andrew Lewis as a subcontract manufacturer of electronic assemblies and circuit boards. In 1986, the company released memory upgrades for Apple Macintosh Computers, its first product. In 1987 the company began to market processor upgrades exclusively...

 manufactured the Macintosh Processor Upgrade Card for Apple, sold the same card as their Daystar PowerCard 601-50/66 and also manufactured a Daystar PowerCard 601/100 which reached 100 MHz. After Daystar went out of business the 100 MHz model was manufactured and sold by Sonnet Technologies as their Sonnet Presto PPC 605.