The Apple IIGS Megahertz Myth

Article & Video Reception

• Readers praise the piece (and related YouTube video) as unusually detailed “digital archaeology,” especially on Apple’s early ARM involvement and Apple IIGS history.
• Some enjoy the narrative style and references; others find the heavy alliteration off‑putting.

Nostalgia, Hardware Durability & Preservation

• Multiple posters still own Apple II machines (often from childhood) that still boot after decades in attics.
• Strong warnings to replace the IIGS lithium backup battery (especially soldered ROM01 versions) before it leaks, and to proactively replace RIFA capacitors in power supplies to avoid catastrophic failure.
• Specific Mouser part numbers are shared for adding a removable battery holder.

Apple II Line, IIGS Identity & Hypothetical Apple IV

• The long commercial life of the Apple II (into the mid‑90s in education) is seen as remarkable.
• Some view the IIGS as a different computer that only emulates the IIe/IIc; others embrace it as the natural evolution, noting accelerators, graphics cards, TCP/IP stacks, and multitasking OSes like GNO/ME.
• There’s playful talk of an “Apple IV” or retro‑styled beige modern machine as a symbolic apology for the Apple ///.

Clock Speed, “Megahertz Myth,” and 6502 vs Z80

• Posters recall 1 MHz 6502 systems feeling faster than higher‑MHz Z80 systems, but others argue this is overestimated.
• Technical points: 6502’s efficient cycles, simple pipeline, and dense zero‑page addressing vs Z80’s more complex instructions and multi–T‑state machine cycles.
• Discussion of why Apple II clocks stayed at 1 MHz: tight coupling of CPU speed to video, DRAM refresh, Disk II timing, and software loops dependent on cycle counts. Accelerators, IIc+ at 4 MHz, and compatibility issues are noted.

Interrupts, VBlank & Game Design

• Lack of standardized vblank interrupts on 8‑bit Apple IIs led to inconsistent frame timing in games.
• Later models and firmware (mouse firmware, status bits) exposed some timing hooks, but they were quirky or underused compared to platforms like C64, consoles, and arcade systems.

Broader 1980s Ecosystem & ARM Origin

• Posters reminisce about the “Cambrian explosion” of incompatible home computers, cassette‑based storage hassles, and minimalist RAM.
• The thread highlights how Acorn’s brush with the 65816 spurred them to design their own RISC CPU, ultimately leading toward ARM and today’s ARM‑based Macs.