Other Cpu StrongARM

Digital Equipment Corporation's ARM-derived processor that made the Newton feel alive and quietly found its way into everything from handhelds to network silicon.

What It Was

The StrongARM began as a joint development between Advanced RISC Machines and Digital Equipment Corporation, producing an ARM-architecture core that delivered clock speeds and performance well beyond what the ARM7 family managed at the time. By the mid-to-late 1990s the SA-110 and the SA-1100 variants had turned up in an uncommonly wide spread of hardware: personal digital assistants, thin clients, Windows CE devices, and the guts of professional network switching silicon. That breadth was not an accident of marketing. It reflected a genuine performance-per-watt proposition that ARM's conventional licensees had not yet matched.

Intel acquired Digital's semiconductor operations in 1998, inheriting the StrongARM line and folding the core into its own embedded roadmap. The IXP 1200 network processor, explicitly described as containing Intel's StrongARM processor core, also incorporated six programmable RISC micro engines alongside it, each engine assigned to monitor a single line within a network switch and route packets accordingly.¹ That architecture could push 2.5 million packets per second through a single device, according to Intel's own figures.¹

The Newton Moment

The most viscerally legible demonstration of what the StrongARM actually meant in practice came in the Apple Newton MessagePad. Earlier MessagePads had a reputation (well earned) for sluggishness that the polite called "marginal responsiveness." The StrongARM at 167 MHz changed the character of the machine outright.⁴ A contemporary review in SunExpert described the difference without hedging: previous MessagePads belonged either to a "WORKS" or "DOES NOT WORK" category, and either way felt as if the user were dragging the device. With the StrongARM, the reviewer wrote, the machine communicated something closer to "You want that? You got that! ZIP!"⁴

The speed mattered most in an area prior MessagePads had not seriously attempted: wireless Internet access. With two PC Card slots and the StrongARM's headroom, the hardware could actually service that use case in the field.⁴ It is one of those cases where a processor upgrade does not merely improve a product. It changes what the product can honestly claim to be.

Windows CE & the Embedded Ecosystem

Microsoft's Windows CE platform treated the StrongARM as a first-class citizen alongside MIPS, PowerPC, x86, and SH3/SH4, five architectures supported equally, which the Windows CE team considered a meaningful differentiator in the embedded space.² In CE version 2.10, support for a 200 MHz processor and the StrongARM 1100 from Digital were both noted, and at least one customer deploying interpreted code judged the available performance sufficient for their application.²

The thin-client market also adopted the SA-110. A product comparison table published in SunExpert in mid-1998 lists the Digital StrongARM SA-110 as the minimum microprocessor for one device category, set against competitors using the ARM 7500FE, Motorola 821, and Intel Pentium-class parts.³ Sitting in that table between a Motorola 821 and a 166 MHz Pentium MMX says something about where the market positioned it: capable enough for serious networked work, efficient enough for fanless thin hardware.

Into the Network

Intel's use of the StrongARM core inside the IXP 1200 represents the architecture's most architecturally ambitious deployment documented in the surviving sources. The IXP 1200 was aimed squarely at network equipment vendors who had previously been forced to commit to fixed ASIC designs at least a year before shipping.¹ The StrongARM core, combined with the six programmable micro engines, offered a software-programmable alternative, allowing vendors to modify functionality without re-spinning silicon.¹ Analyst Nathan Brookwood of Insight 64 in Saratoga, CA, put it plainly: with a single IXP 1200 and an additional interface, a vendor could build a product that was primarily software-driven and still matched the functionality previously requiring dedicated hardware.¹

Network equipment companies including Broadband Access Systems, Cabletron Systems, Cisco Systems, and Newbridge Networks were already planning IXP 1200 support at the time of reporting.¹ That is a credible list. Cisco's presence alone signals that Intel was not pitching a niche experiment.

Legacy

The StrongARM occupies an odd position in processor history: genuinely influential, but rarely the thing anyone named when they named the thing they loved. Newton users remember the Newton. Windows CE developers remember CE. Network engineers remember the IXP line. The processor underneath all of them did the work without getting the credit, which is perhaps the most honest summary of a successful embedded architecture. Intel would eventually develop the StrongARM heritage into the XScale line, but the sources here are silent on that transition's details, and inventing a timeline would do the record no favors.

References

1. ServerWorkstationExpert-v10n11-1999-11 (1999)
2. Inside Microsoft Windows CE John Murray 1998 (1998)
3. SunExpert-v09n07-1998-07 (1998)
4. SunExpert-v08n03-1997-03 (1997)