“Okay,” came the reply, “that’s it. We’ll get rid of the disadvantages of the Apple and cram our computer into one box without cables all over the place.” In ads the Apple looked incredibly compact. Actually, though, serious computer users needed disk drives to store large amounts of information for quick retrieval. They also needed a TV-like monitor to see the letters and numbers they typed out on the computer. And Kay wisely wanted everything squeezed into one box. If you bought his machine, you’d get the whole works except perhaps for the printer, which spewed out your calculations or typed up your letter. Also, it would cost you less than a full Apple system. Kay could bring down the cost of a complete machine if he planned on every computer being one.
All this was the logical culmination of Kay’s skill in shrinking gear for the military and aerospace industry. For years he had been making printed circuit boards and filling them with components. And he could order the disk drives, keyboards, and other special computer-type parts from outside suppliers.
The way Kay tells it, he had no idea—at first—that he was about to take on Adam Osborne. “It was six months,” he said, “before we ever saw Osborne’s literature. He introduced his computer in March 1981, but I didn’t know anything about it.” Some would question that statement, of course, given the novelty of the Osborne 1 and its creator’s flair for publicity.
Whatever happened—with Osborne in mind or not—Kay selected the same basic technology and essentially similar parts.
A Z80-Style Microprocessor
A microprocessor is simply the main brains that tie together the memory devices, the keyboard, and other parts of the computer. You can also call it a central processing unit (CPU).
Okay, but why a Z80 in the Kaypro?
That’s simply a style of chip from a company called Zilog. “You could buy those all over the place,” Kay said. “We wanted something proven and reliable.” The Z80 was the only kind of CPU that could run CP/M (Control Program for Microcomputers)-style programs, then an industry standard.
The Z80, though, can’t handle programs as complicated as the newer 8088 chip that ended up in IBM PCs and countless clones. Here’s why.
A bit is a “1” or a “0.” Patterns of bits form bytes. And what’s a byte? Nothing more than a letter or number. So how does this tie in with the early Kaypro’s Z80 versus the IBM’s 8088?