# How the Apple Macintosh Works How the 1984 Apple Macintosh turns a mouse click and a keystroke into the picture on its screen, from the processor and memory to the electron beam\. By sunny\-koala\-10215ae1 Topic: Computing, AI & Electronics [Open the interactive Jig](https://ask.jig.com/j/DbHLs00Vw9bh) ## Transcript ### 1. A computer for everyone In January 1984 Apple launched the Macintosh: a screen, a computer and a disk drive in one beige box\. Instead of typing commands, you pointed at little pictures with a mouse\. Let's look inside and see how it works\. It cost US$2,495 and weighed 7\.5 kg \(16\.5 lb\)\. Drag anywhere to turn the desk around\. ### 2. Slide off the case The back of the case slides away, leaving a metal frame packed with parts\. The picture tube sits at the top, the disk drive under it, and a board along the side turns wall power into what the parts need\. There is no fan: warm air simply rises out of the vents\. Never open a real one\. The picture tube can hold a dangerous charge long after it is unplugged\. ### 3. The brain is a chip The logic board lies under everything\. Its Motorola 68000 processor, the long black chip, follows millions of simple instructions every second\. It reads built\-in programs from ROM chips \(read\-only memory\) and keeps its work in RAM chips \(memory that forgets when the power goes off\)\. 128 KB of RAM in sixteen chips, 64 KB of ROM in two, and a clock ticking about 7\.8 million times a second\. ### 4. A picture made of bits The screen is a grid of 512 by 342 dots called pixels\. Each dot is only black or white, so one bit of memory, a 1 or a 0, is enough to remember it\. Slide to zoom in and see the dots\. That is 175,104 pixels, stored in about 21 KB: a sixth of all the memory\. ### 5. Painting with electrons At the back of the picture tube, an electron gun fires a thin stream of electrons at the glass\. The copper coils, called the yoke, steer it across one row at a time, and wherever it lands a coating called phosphor glows\. Here it is slowed right down; the real beam repaints the whole screen about 60 times a second\. The real beam is invisible\. The glowing line only shows its path\. ### 6. Point and click Under the mouse is a rubber ball\. As it rolls, it turns two little slotted wheels, one for left and right and one for forward and back\. The computer counts their flickers and moves the arrow on the screen to match\. ### 7. Feed it a disk The first Mac had no hard drive\. It started from a 3½\-inch floppy disk that holds 400 KB\. Until a disk goes in, the screen shows a disk with a blinking question mark\. There is no eject button: you drag the disk's picture to the Trash and the Mac pushes the disk out\. ### 8. Everything together Press a key and the keyboard sends a code down its coiled cord\. The processor changes the picture in memory, and the beam paints the new letters on its very next sweep\. It all happens faster than you can blink\. The signatures of the team who built it are moulded inside the case, like artists signing their work\.