![]() It shows that code density of modern RISC CPUs is way behind where it could be. Sweet 16 is an impressive example for high code density.Ħ bytes for a memcpy routine! Try that on modern processors.Īnd also note that this code would work the same way in a 32-bit or 64-bit environment. The code can of course be ported to any other processor or written in C.ĠB RS (Return from Subroutine - Stay in Sweet16 mode The high byte of the address to be identical) On the 6502, an 8-bit Jumptable was used, which required all relevant code to be located in the same page (meaning However, the code can use any other range.įor program space, about 300 bytes are required for the implementation on the 6502. In the original Apple implementation, the first 32 bytes located from $0 -$1F were used, SWEET16 requires storage in the zero page area for the registers. For more information on SWEET16, see Memory allocation Despite its simplicity, Sweet 16 achieved an amazing code density, which is still hard to beat today. 6502 assembler and Sweet 16 could be mixed easily: Sweet 16 code was inlined and simply preceeded by a function call to the executer, which was located at a known address (0xF689 or in Apple speech $F689) could easily be started by a subroutine call. The Sweet 16 executer was implemented in the ROM of the original Apple ][. Typical programs written in SWEET-16 needed about half the size and 5 to 10 times as much time as pure 6502 assembly code. It required 32-bytes in the Zero page of the 6502, to hold the values of these registers and needed less instructions than the 6502 for most programs. R13 – stores the result of all comparison operations.Some registers have well-defined functions: Do not approach your loved one while in your fighting stance or she’ll kick you in the head.SWEET16 has 16 internal 16-bit registers, named R0. ![]() Ars Technica’s Casey Johnston reviews Karateka, 30 years later.Jason Scott of The Internet Archive debuts the Historical Software Archive based on JSMESS.Charles Mangin’s joystick adapters, courtesy option8 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak for the Apple machines.Building an Apple-1 replica from scratch.Apple Time Warp podcast with John Romero and Craig Johnston (also available on iTunes).Chrisann Brennan’s book about Steve Jobs, The Bite in the Apple.Steve Weyhrich’s Sophistication & Simplicity, based on the Apple II History site, now available from and Barnes & Noble Though only virtual, the similarities in architecture, the instruction set, and the nibble-based opcodes make me wonder if Woz built an Elf just prior to.Twine - an open-source tool for telling interactive, nonlinear stories.Andrew Plotkin’s Hadean Lands: Interactive Fiction Kickstarter.Creating Interactive Fiction with Inform 7, by Aaron Reed.Xbox One first impressions with Lon Seidman.Apple II guest speakers at Emerson College.Finally, Ken, in his quest to be more Woz-like, adopts his hero’s fashion sense.Ĭlick past the jump for links mentioned in this episode. Jason Scott has integrated the JSMESS emulator into the Internet Archive, granting users unprecedented access to historical software right in their browsers. Both Steve Weyhrich’s history book and the Steve Jobs movie are available for home delivery, but there’s only one we want to find under our Christmas tree. Text adventures are enjoying a resurgence in popularity and access, and Andrew guides us through the tools and resources available for aspiring game authors. This month on Open Apple, Mike and Ken chat with Andrew Schultz - gamer, FAQ author, and Interactive Fiction Competition participant.
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