MPUs inching closer to 64-bit computing

Electronic News, Sept 19, 1994 by Reinhardt Krause

NEW YORK - The advent of "64-bit" computing will inch a bit closer as IBM/Motorola, Hewlett-packard and Sun Microsystems reveal more details about their new 64-bit microprocessors. While demand for 64-bit computing is just beginning to percolate, the PowerPC 620 and PARISC 8000 MPUs to be described at the upcoming Microprocessor Forum and the UltraSparc MPUs to be unveiled this week - as well as incumbent Alpha AXP and MIPS processors - target the industry's transition from the 32-bit to 64-bit world.

Estimates vary on how and when 64-bit computing will emerge. While demand may just now be appearing in applications such as video servers, 64-bit addressing will not be accepted in enterprise servers, high-end engineering/commercial workstations and other early adopters until sometime after 1995. The wait for 64-bit computing on the desktop will take even longer and could stretch out until the next decade.

The stakes will be big, though. Intel - through its recent alliance with HP to develop a 64-bit binary-compatible MPU (EN, June 13) will try to move into new high value applications. Sun Microsystems, whose Sparc architecture has fallen behind in the performance race of late, will attempt a comeback (see story, page one). DEC, having endured a transition from its VAX architecture to the Alpha AXP platform, will try to make its gamble pay off. The PowerPC alliance of IBM and Motorola - now attempting to catch Intel in its traditional base - will have a new playing field.

But many pieces need to fall into place before 64-bit computing takes hold, according to several MPU vendors interviewed by Electronics News. And the industry's transition from the 32-bit to 64-bit systems - while bearing some similarities to the 16-bit to 32-bit transition - will have important differences.

For example, since 32-bit MPU architectures provide a 4GB address space - there will not be pent-up demand as took place earlier during the move from 16-bit to 32-bit systems, said Andy Keane, MIPS Technologies manager of microprocessor product marketing.

While the 64KB address space of 16-bit MPUs was very limiting, it will still be some time before the 4GB provided by 32-bit architectures becomes constrained. One of Mips system customers will roll out a system with 4GB main memory later this year, however.

In fact, pricing and density trends in the DRAM market will have a big impact on when 64-bit computing really takes off, several MPU vendors agree. Except for national laboratories, who can afford the physical memory in the machines to make use of giant addressing? they ask. Some, such as Sun's David Ditzel, chief scientist and director of SPARC Labs, suggest 64-Mbit DRAMS will need to move into volume production or even 256-Mbit devices.

Aaron Bauch, DEC's manager of semiconductor applications, said system memory cost will be a factor for some time. "You can plot out all kinds of trends with a bit and half per year kind of estimates for the hunger or thirst on memory space and it also does follow the trend of the cost of memory. So if you say my system can tolerate $200, $500, or $1,000 worth of memory what that buys you at any point in time is constantly increasing by the way the DRAM increases in density."

While video servers and high-end CAD environments are beginning to push multigigabyte address spaces, Mr. Bauch noted that desktops are still shipping with 2MB to 8MB of main memory and high-end workstations with 128MB. "It's a question of do you hit that wall in 1994, 1995 or 1997 or 1998 or is it 2001," he said. "That's where you get interesting discussions. But I don't think anyone will argue that you hit it toward the end of this decade."

While the installed base of 64-bit hardware is likely to arrive before 64-bit operating systems, some MPU vendors see the emergence of new operating systems as another important factor. However, there is some debate as to what will emerge first - a standard for 64-bit Unix or a 64-bit version of Microsoft's Windows NT.

Despite the success in forging Spec 1170, not all think there will soon be a 64-bit Unix version to follow. Spec 1170 - a new 32-bit specification that will attempt to unify the many flavors of Unix by ensuring portability of applications between platforms - has just been completed. Spec 1170 incorporates about 1,170 Unix application programming interfaces (APIs) and will supersede the current XPG4 specification. It is currently being reviewed by X/Open Co. Ltd. and is expected to be approved in Q3.

Larry Inman, HP's program manager for Advanced Technologies, sees open system standards as critical for independent software vendors (ISVs) to begin writing 64-bit applications. "From their standpoint, they are keen on the ability of leveraging across multiple platforms," he said. "It's the latter half of the '90s when we really see ISVs starting to embrace and push forward with applications that take advantage of 64-bit functionality. It'll be the year 2000 and beyond when the end-user is pushing for 64-bitness."