He’s worked here since before we even had a company. WOZNIAK: Yes, it’s used in EDASM, mostly in the editor portion.
#Sweet16 wozniak code
It was easy to mix Sweet-16 code with assembly language.īYTE: Isn’t Sweet-16 still used in Apple DOS and ProDOS editor/assemblers? But I did use it in later years to write things like BASIC renumbering routines totally in Sweet-16. WOZNIAK: No, I never had the time to reimplement the BASIC to use it. It ran about 30 times as slow as 6502 assembly language, but it saved tons of code every time I used it in a program.īYTE: Did you actually use it in your Integer BASIC? So I decided to write a little emulator and implement a 16-bit machine that could interpret pseudocodes and implement registers 0 to 15 in the 6502 base page. There were several places where I had to handle 16-bit pointers with an 8-bit processor. I had been thinking about ways to save code. In this part, the conversation switches to various aspects of the Apple II design, later personal history, and Steve’s thoughts about the personal computing industry.īYTE: One of the more interesting things in the Apple II ROM was your 16-bit pseudomachine called “Sweet-16.” How did you come up with that? Steve talked about his background, the evolution of the Apple I and II, and the early days of the company. They can be contacted at POB 372, Hancock, NH 03449. Rob Moore is a hardware designer and frequent contributor to BYTE. Gregg Williams is a senior technical editor at BYTE.
Apple Computer then turned to Microsoft to adapt their version of BASIC, which supported floating-point instructions, into Applesoft BASIC.Conducted by Gregg Williams and Rob Moore Because scientific users requested floating-point support, Wozniak included routines that could be called from the ROMs, but did not have time to integrate them into his Apple BASIC interpreter, which he considered to be the most challenging part of designing the Apple I and II computers. Īpple BASIC was included directly in the ROM of the Apple II computer, released in 1977. However, it was not compatible with the dialect of Microsoft BASIC that Bill Gates had based on Digital Equipment Corporation's BASIC-PLUS.
As games at the time mainly relied on integer functions, he implemented a small virtual machine called "Sweet 16" to support 16-bit integers. Because the standard configuration of the Apple I only contained 4KB of RAM, Wozniak did not have enough room to implement floating-point instructions, which he said also saved himself a few weeks' worth of development time. In 1976, Apple BASIC was provided to Apple I owners on a cassette tape that took about 30 seconds to load. Preliminary Apple BASIC users manual, dated October 1976
The first program that Wozniak tested on the Apple I's BASIC interpreter was an early Star Trek text game the source code had already been ported to HP BASIC for the HP 2000C minicomputer. Wozniak designed the Apple I around this implementation of BASIC, but was unable to afford a compiler at the time, so he hand assembled the instructions which he coded directly into machine language for the MOS 6502 processor. Wozniak assembled folders of papers for his BASIC design, which was based on a dialect developed for minicomputers by Hewlett-Packard, where Wozniak worked at the time.
#Sweet16 wozniak software
The Celebration Apple-1 BASIC Cassette TapeĪfter working on the video game hardware of Breakout with Steve Jobs at Atari in 1975, Wozniak started work on Game BASIC so he could write games in software without resorting to machine language.
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