The Apple Macintosh Computer Mouse-window-desktop technology arrives for under $2500 by Gregg Williams Apple established itself as one of strengthened that reputation with a The Macintosh arrives, finally, after the leading innovators in personal new machine, the Macintosh (above). a history of colorful rumors. It will computing technology a year ago by In terms of technological sophistica- cost from $1995 to $2495, weighs 22.7 introducing the Lisa, a synthesis and tion and probable effect on the mar- pounds, and improves on the mouse- extension of human-interface tech- ketplace, the Macintosh will outdis- window-desktop technology started nology that has since been widely tance the Lisa as much as the Lisa by the impressive but expensive Lisa imitated. Now the company has has outdistanced its predecessors. computer. A system with printer and 30 February 1984 C BYTE Publications Inc. second disk drive costs about $900 corner are selections for the current commercial product: the graphics/ more, but even at that price, the line width. By selecting the "open mouse orientation, the desktop meta- Macintosh is worth waiting for. oval" tool and the thickest line width, phor, the data-as-concrete-object we can draw empty ovals with thick metaphor, and the shared user inter- The Macintosh at Work borders (figure 1d). By selecting the face between programs. The Mac has Before we look at the Macintosh (or "paint bucket" tool and the "diagonal inherited these concepts; for further Mac) in more detail, lets look at how bricks" pattern, we can fill the oval details on them, see my article, "The it works. When you turn the Mac on, with that texture (figure le). The Lisa Computer System" (February 1 its screen tells you to insert a 3 /2-inch "eraser" tool lets us erase part of the 1983 BYTE, page 33). Sony floppy disk. When you do that, image (figure 1f); for finer control, we Four differences between the Lisa the Macintosh puts a disk icon on the can give the FAT BITS command and the Mac make the latter a screen along with the disks name. As (figure 1g), which allows us to erase second-generation computer. First, with the Lisa computer, you first or paint on a pixel-by-pixel basis. the Mac runs at a higher clock speed, select an object, then choose a menu When we are finished with our im- 7.83 MHz (compared to the Lisas 5 item that works on the object. Say, for age and select the QUIT command, MHz). Second, the Mac, which has example, we choose the disk by mov- the program displays an alert box that a smaller amount of memory to work ing the cursor to the disk icon and asks if we want to save our changes with than the Lisa, uses its memory clicking the mouse button once (figure 1h). more efficiently because its programs (figure la). The disk "opens up," and subroutines are coded in 68000 showing a window containing icons, Foundations of Macintosh Design assembly language (as opposed to each one of which corresponds to an The Macintosh computer is built on the Lisa, which uses less efficient item on the disk. To start using the three cornerstone ideas: second-gen- 68000 machine-language programs Mac Paint program, we select the eration Lisa technology, reliability that are compiled from high-level Mac Paint icon and choose the menu and low cost through simplicity, and Pascal source code). Third, the item "open," as shown in figure lb. maximum synergy between hard- Macintosh eliminates add-on periph- (We also could have opened Mac ware and software. Each of these eral cards and uses instead a high- Paint by double-clicking on the icon.) ideas contributes significantly to the speed serial bus that implements What follows is a brief example of uniqueness of the Macs design. what Apple calls "virtual slots." (I will how the Mac Paint program works. talk about this in greater detail When we open the program, we get Second-Generation below.) the screen of figure 1c. The large Lisa Technology The final difference is actually an blank area is a window onto the Without question, the strongest in- important limitation of the Macin- drawing area, the boxes on the left fluence on the Mac is that of the tosh: it allows only one major ap- are tools, the boxes on the bottom Apple Lisa computer, which proved plication program to be active at a row are patterns, and the lines in the the viability of certain concepts in a time (the Mac BASIC and "desk ac- Memory Hardware Options At a Glance 128K bytes of RAM. 64K bytes of ROM Second disk drive, keypad, Imagewriter Standard Configuration printer, security kit (for chaining com- Name Main unit with 128K bytes of RAM, 64K puter to table) Macintosh bytes of ROM, integral Sony 3½-inch Software Options disk drive, 9-inch video monitor, two Mac Paint (drawing program), Mac Write Manufacturer serial ports; external mechanical mouse: (a si mple word processor), Mac BASIC, Apple Computer external keyboard Mac Pascal, others (see text) 20525 Mariani Ave. Mass Storage Prices Cupertino, CA 95014 One Sony 3½-inch disk drive; 3½-inch Standard system, S1995-S2495 : Mac Paint (408) 996-1010 disk holds 400K bytes and is encased in and Mac Write (together), bundled at no a rigid plastic housing charge for the first 100 days, S195 (for the Dimensions Video Display two) thereafter; Macintosh Pascal, BASIC, 9.75 by 9.75 by 13.5 inches 9-inch monitor, noninterlaced 60.15-Hz Logo. Terminai, and Assembler/Debugger, Weight image, 512- by 342-pixel resolution S99 each; Mac Draw and Mac Project, Main unit. keyboard and mouse—22.7 Pointing Device $125 each; keypad, S99; second disk Ibs Mechanical mouse drive, $395: Imagewriter printer, $495 Power Requirements Keyboard 105-130 V AC, 60 Hz (U.S. model); Detached keyboard; 58 keys (59 in inter- 85-135 V AC, 50/60 Hz (international national version); autorepeat; two-key model) rollover February 1984 BYTE Publications Inc. 31 Macintosh System Architecture by Burrell C. Smith Inside the Macintosh, hardware and pears in memory as a linear array of 10,944 a tightly coded routine generates 370 software work together to provide a system 16-bit words of data, with the most signifi- samples of sound data and places them into capable of supporting high-performance cant bit representing the pixel farthest left. the sound buffer just after a vertical retrace graphics, built-in peripherals, and commu- Each 512-pixel horizontal line consists of interrupt. The 68000 's 32-bit registers are nication channels to the outside world. 32 words of data, with bits shifted out at used to control pitch with 24 bits of preci- From the beginning of the Macintosh pro- 15.67 MHz (322.68 µs per 512-pixel line) sion, providing each of four possible voices ject, the product-design goals of small size, followed by 12 words of horizontal blank- with 16,777,216 possible frequencies. For light weight, and moderate end-user cost ing (taking 12.25 as). The last memory bus simpler sounds, a timer in the systems encouraged us to create a low-power, low cycle ofeach horizontal line is reserved for VIA provides a square wave of program- component-count design. The large num- sound DMA, where a byte of sound data mable pitch. All sounds pass through a ber of I/O devices that are built into each is fetched from the sound buffer and sent software-controlled volume adjustment unit, combined with our desire for high to the sound PWM (pulse-width modula- that creates approximately 20 decibels of performance, caused us to explore many tor) for conversion into an analog level. The total amplitude variation in eight discrete alternatives for each aspect of the hardware update rate of the sound channel is then steps. implementation. A cooperative spirit equal to the video horizontal rate, or The Macintosh disk controller is a single among the people working on the in- 22,254.55 Hz. In the vertical direction, LSI (large-scale integration) component dustrial design, analog electronics, digital 342 active scan lines are followed by a ver- referred to as the IWM ("integrated Woz electronics, and low-level software resulted tical retrace and enough inactive horizontal machine") chip. The device, a one-chip in- in the synthesis of detailed implementa- tegration of the disk controller originally tions that combined strengths from each The product-design designed by Steve Wozniak for the Apple group, providing an integrated design solu- It, handles data at 500 kilobits per second. tion for all aspects of the product. goals of small size, To control the disk drives motor speed, a The heart of the Macintosh digital elec- light weight, and pulse-width modulator located on the tronics is the MC68000 processor and its digital board allows the disk to move at one memory (both RAM and ROM). In the moderate end-user cost of 400 possible disk motor speeds; the Macintosh, the data-output lines from the encouraged us to PWM is driven from a table in memory in system RAM drive a data bus separate create a low-power, a fashion similar to that of the sound sys- from that used by the rest of the machine tem. By varying the motor speed, we (see figure 2). The RAM is triple-ported; low component-count created a more reliable disk drive that puts this means that the 68000, screen-display- design. significantly more data on the same disk. ing hardware, and sound-output hardware The Macintosh communications chip, have periodic access to the address and data lines to take up the same time as 28 hori- the Zilog 8530 SCC (serial communica- buses, so that the video, the sound, and zontal lines, providing a vertical retrace tions controller), provides synchronous and the current 68000 task appear to execute time of 1.258 ms.