The buzz in the tech world reached a fever pitch when Microsoft CEO Steve Ballmer unveiled the HP Slate during his CES 2010 keynote, brandishing it as Windows 7's answer to the burgeoning tablet revolution. Yet, conspicuously absent from the initial fanfare was a critical detail: precisely what silicon heart would power this ambitious device. HP's coyness ignited intense speculation across forums and analyst reports, transforming a simple hardware question—"What processor is inside?"—into a referendum on the very viability of running a full-fledged desktop OS like Windows 7 in a sleek, portable form factor. Would HP prioritize raw performance with Intel’s Core series, or chase iPad-rivaling battery life with the low-power Atom—specifically the then-unreleased "Moorestown" platform? This ambiguity wasn't just technical nitpicking; it foreshadowed the fundamental compromises and challenges that would plague Windows tablets for years.

The Contenders: Silicon Showdown for HP's Tablet Ambitions

Industry whispers and HP’s own internal deliberations, later confirmed by executive interviews and leaked roadmaps, centered on three distinct Intel architecture paths, each representing a starkly different vision for the Slate:

  • Intel Atom "Moorestown" (Z5xx Series): The presumptive frontrunner, designed explicitly for smartphones and tablets. This system-on-chip (SoC) promised dramatically reduced idle power consumption compared to its "Menlow" predecessor (used in netbooks), theoretically enabling all-day battery life. Integrated graphics (GMA 600) and a single-core architecture (like the Z540 at 1.86GHz) targeted basic tasks and media playback. Crucially, it allowed for fanless designs, essential for thin-and-light tablets. As Phil McKinney, then HP's CTO for Personal Systems, hinted in numerous interviews, battery life was paramount. "You have to have a device that doesn't become a boat anchor... that doesn't die on you halfway through a flight," he emphasized, aligning strongly with Moorestown’s pitch.
  • Intel Core 2 Duo (SU Series): The established ultra-low-voltage (ULV) mobile chips, like the SU9600 (1.6GHz dual-core). These offered significantly higher CPU and GPU (GMA 4500MHD) performance, capable of smoother multitasking, light photo/video editing, and better compatibility with legacy Windows applications. However, they came with steep penalties: higher thermal design power (TDP ~10W vs. Moorestown's ~1.3W idle/~2.5W load), necessitating active cooling (fans) and thicker chassis, plus drastically reduced battery endurance—perhaps 3-4 hours versus a target of 8+.
  • Intel Core i3/i5 (UM Series): The newer "Arrandale" ULV processors (e.g., i5-520UM, 1.06GHz dual-core with Turbo Boost). These represented a performance pinnacle for the form factor, introducing modern features like hyper-threading and significantly better integrated graphics (Intel HD). Yet, they exacerbated the Atom's downsides: even higher TDP (~18W), demanding active cooling, greater cost, and battery life likely measured in hours, not a full workday. Their presence on the rumormill likely stemmed from HP's desire to position the Slate as a true laptop replacement for business users, but practical implementation in a true iPad competitor seemed improbable.

Why Not ARM (like Apple's A4)? Speculation briefly flitted around the Apple A4 chip powering the iPad, but this was swiftly dismissed by technical reality. Windows 7, in its entirety, relied exclusively on the x86 instruction set. ARM processors, including the A4, used a fundamentally different architecture (ARMv7). Porting Windows 7 to ARM would have been a monumental, multi-year undertaking—far beyond the scope of HP's imminent Slate project. Microsoft wouldn't attempt this until Windows RT, years later.

The Battery Life Conundrum: Windows 7's Hefty Appetite

The processor choice was intrinsically linked to the Slate's most critical usability metric: battery life. Independent testing by AnandTech and Laptop Mag during that era consistently demonstrated a harsh truth. Even Intel’s most frugal Atom netbooks running Windows 7 struggled to exceed 6-7 hours under light use. The iPad, powered by the efficient ARM-based A4 and a lightweight OS (iOS), effortlessly achieved 10+ hours of video playback. Windows 7, designed for desktops and laptops with larger batteries, carried inherent overhead:
- Background Services: Automatic updates, indexing, security suites.
- Graphics Driver Complexity: Full DirectX support vs. simpler mobile rendering.
- Memory Footprint: Requiring 1-2GB RAM just for the OS, compared to iOS's leaner usage.
- x86 Inefficiency: Legacy support and architectural differences meant x86 chips consumed more power per operation than contemporary ARM designs for similar tasks.

Choosing a Core-series processor would doom the HP Slate to battery life figures far below consumer expectations set by the iPad, making "all-day computing" impossible. McKinney's public focus on battery life strongly signaled that Moorestown was the only viable path if HP wanted to compete on mobility.

The Moorestown Mirage: Promises vs. Reality

Intel heavily promoted Moorestown (officially the Atom Z6xx series) as a revolution for smartphones and tablets. Benchmarks leaked to Engadget and ZDNet in early 2010 touted significant idle power reductions—up to 50x lower than Menlow. However, deep dives by AnandTech upon its release revealed critical shortcomings:
- Load Power Wasn't Low Enough: While idle power was impressive, power under load was only marginally better than older Atoms. Running Windows 7, especially with multiple applications or HD video, still drained batteries quickly.
- Performance Lagged: The single-core, in-order execution architecture struggled with the demands of full Windows 7. Tasks like opening complex Office documents, multitasking with several browser tabs, or even navigating the OS itself felt sluggish compared to Core chips or even contemporary ARM tablets.
- Graphics Limitations: The GMA 600 GPU, while improved, still couldn't handle HD video decoding efficiently in software or provide a fluid experience for basic UI animations expected on a touch device. Hardware acceleration in Windows 7 was patchy.
- Ecosystem Delays: Moorestown arrived later than anticipated, contributing to the HP Slate's delayed launch.

The Verdict Revealed: Atom Inside, Compromises Ensue

When the HP Slate 500 finally launched in October 2010, the mystery ended: it featured an Intel Atom Z540 processor (single-core, 1.86GHz), part of the Moorestown platform, paired with 2GB of RAM. HP's choice validated the focus on form factor and battery life over raw power. Specifications listed on HP's official datasheets and reviewed by CNET and PCWorld confirmed the fanless design and a quoted battery life of "up to 5 hours," a figure real-world tests often found optimistic for anything beyond light use.

Critical Analysis: A Well-Intentioned Misfire with Lasting Lessons

The HP Slate 500 was a bold, necessary experiment, but its processor choice encapsulated its fundamental struggles:

Strengths & Intentions:
- Commitment to Full Windows: HP delivered a genuine Windows 7 PC in a tablet form, ensuring complete compatibility with existing enterprise software, peripherals, and security tools—a key differentiator versus the iPad for business users.
- Fanless, Compact Design: The Atom Z540 enabled a relatively thin (0.6 inches), quiet device without compromising the full OS experience.
- Niche Enterprise Appeal: For specific vertical markets (healthcare, field service, point-of-sale) needing a ruggedized Windows tablet with pen input (it included an active digitizer), the Slate 500 found a dedicated, if small, audience.
- Pushing Intel: HP's commitment forced Intel to accelerate its low-power x86 roadmap, paving the way for future, more successful iterations like the Atom "Clover Trail" in Windows 8 tablets.

Weaknesses & Risks Realized:
- Battery Life Shortfall: The "up to 5 hours" paled against the iPad's 10+, undermining the core promise of mobile productivity. Moorestown couldn't overcome Windows 7's inherent power demands.
- Performance Bottlenecks: The single-core Atom proved inadequate. Navigation felt laggy, app launches were slow, and multitasking was painful. Ars Technica's review bluntly stated it "struggled with the basics," creating a poor user experience compared to snappier ARM tablets.
- Cost vs. Value: At $799, the Slate 500 cost significantly more than the entry-level iPad ($499) while offering worse battery life, performance, and app ecosystem for consumers. This pricing, partly driven by the Windows license and business features, hindered mass adoption.
- Windows 7's Touch Unfriendliness: The OS wasn't designed for touch-first interaction. Tiny interface elements, reliance on right-clicks, and poor keyboardless operation made it awkward, regardless of the silicon. The processor choice couldn't fix this OS-level flaw.
- Thermal Throttling: Despite being fanless, sustained loads could cause the Atom chip to throttle, further reducing performance—a catch-22 for users pushing the device.

The Unraveling and Legacy:
The HP Slate 500 arrived late, underperformed, and was quickly overshadowed. HP's acquisition of Palm shortly after signaled a strategic pivot towards webOS for tablets (the ill-fated TouchPad), effectively abandoning the Windows tablet path it had championed. The device faded from the consumer market, becoming a cautionary tale.

Yet, its legacy is profound. It highlighted the impossibility of grafting a desktop OS designed for high-power x86 chips onto a mobile form factor without revolutionary changes. Moorestown proved insufficient. This failure directly influenced Microsoft's future strategies:
1. Windows 8 & RT: Microsoft aggressively optimized for touch and created Windows RT (for ARM) alongside x86, acknowledging the need for OS-level change and ARM's power efficiency.
2. Intel's Urgent Evolution: Intel redoubled efforts on low-power x86, leading to the more competitive Atom "Bay Trail" and "Cherry Trail," and eventually the hybrid Core "Y-series" and successful "Core M" (later Core i5/i7 Y and U-series) chips that finally balanced performance and battery life adequately for tablets and thin laptops.
3. The App Gap Lesson: The Slate experience underscored that simply running legacy Windows apps wasn't enough; touch-optimized applications were essential, driving investment in the Windows Store model.

The HP Slate 500's processor saga wasn't just about choosing a chip; it was a high-stakes gamble on whether traditional PC architecture could adapt swiftly enough to a mobile world defined by ARM efficiency and intuitive touch interfaces. By choosing the Moorestown Atom, HP made the only realistic choice available at the time for a Windows tablet, but it laid bare the harsh limitations of both the silicon and the operating system. It proved that competing in the tablet arena required more than just shrinking a laptop—it demanded a fundamental rethinking of hardware-software synergy, a lesson Microsoft and its partners would spend the next decade learning, iterating, and ultimately, with devices like the Surface Pro line, finally mastering. The ghost of the Slate's struggles—the eternal tension between performance, battery life, and usability in a mobile Windows device—still echoes in every modern tablet design.