Apple II

Atari 2600 Hardware Acceleration

January 23, 2023 Big Mess o' Wires

Atari 2600 programming techniques are fascinating. The hardware is so very limited, and programmers must use every possible trick to scrimp and save the last CPU cycle and byte of RAM. For a refresher on the 2600 hardware, check out my previous Atari overview. The console’s longevity is remarkable, …

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Apple II

Thoughts on an Apple II FPGA Coprocessor

January 22, 2023 Big Mess o' Wires

I’ve been kicking around the idea of using the on-board FPGA in my Yellowstone Universal Disk Controller as a general-purpose Apple II coprocessor. With an FPGA on a peripheral card connected to the 6502 address and data buses, I can’t make the CPU run any faster, but maybe I can …

Apple II

New Macintosh Firmware Updates for Floppy Emu

December 21, 2022 Big Mess o' Wires

Here’s another big Macintosh firmware update for the BMOW Floppy Emu disk emulator, and it’s got some good stuff! Writable MOOF images, in-emulator disk formatting, performance improvements, and a significant bug fix. If you’re the impatient type, skip the rest of this text and download the new firmware now …

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Apple II

BMOW Quality Control Breakdown

December 20, 2022 Big Mess o' Wires

I need a QA team with a suite of regression tests! The BMOW Floppy Emu disk emulator supports many different emulation modes, disk image types, and usage scenarios, so it’s easy to break something without realizing it. If I break something big and obvious that escapes my testing, people will …

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Apple II

AVR-GCC Compiler Makes Questionable Code

December 16, 2022 Big Mess o' Wires

Most people believe that modern compilers generate better-optimized assembly code than humans, but look at this example from AVR-GCC 5.4.0 with -O2 optimization level: 7b96: 10 92 34 37 sts 0x3734, r1 ; 0x803734 7b9a: e0 e0 ldi r30, 0x00 ; 0 7b9c: f0 e0 ldi r31, 0x00 ; …

Apple II

Mysteries of Macintosh High Density MFM Disks

December 16, 2022 Big Mess o' Wires

In the classic Macintosh world, 400K and 800K floppy disks use GCR encoding but 1440K disks use MFM encoding. The BMOW Floppy Emu disk emulator has supported 1440K MFM disk emulation for years, and I thought I knew everything about how it worked. Recently I dug into Mac MFM again, …

Apple II

MOOF disk image support for Floppy Emu

December 3, 2022 Big Mess o' Wires

Good news! Today’s BMOW Floppy Emu firmware update brings support for the Macintosh MOOF disk image format. MOOF is a new disk image format for 3.5 inch Macintosh floppy disks, designed by John K. Morris, with the goal of capturing all the low-level disk information needed for copy-protected software. …

Apple II

An Idea for Macintosh Disk Daisy-Chaining

November 30, 2022 Big Mess o' Wires

The Apple II family of computers supports daisy chaining disk drives, but the classic Macintosh family sadly does not. This means it’s impossible to create a Mac equivalent of Floppy Emu‘s Apple II Dual 5.25 Inch Floppy emulation mode, or its four-disk Smartport hard disk mode. Apple II computers …

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Apple II

Floppy Emu Update: Odds and Ends

November 28, 2022 Big Mess o' Wires

Here’s one more firmware update for the BMOW Floppy Emu disk emulator for classic Apple computers. This update resolves some minor problems and inconsistencies that were discovered in the previous version, but don’t get too excited because it’s all small stuff. Macintosh/Lisa Fixed a bug that broke the display …