Are We Ready For 64-Bit CNCs?

I've got more bits than you so I'm better! It's a debate that is as old as computers and still going on. I first became aware of the debate in the early 1970's as mini-computers were being integrated into control systems.

I've got more bits than you so I'm better! It's a debate that is as old as computers and still going on. I first became aware of the debate in the early 1970's as mini-computers were being integrated into control systems. The issue then was 8 bits versus 16 bits. Historically, the winner was the one who had the most bits—or at least this was the case between 8 bits versus 16 and between 16 bits versus 32. But, is that rule true for the 32 bit verses 64 bit debate going on today? The following takes a look at the new computer "bit debate" which has recently moved into the CNC arena.

Two technology challenges have been consistent driving forces for processor manufacturers and these are the central issues of the "bit debate": (a) skyrocketing demands for CPU horsepower and (b) bit limit that affects the size of file addressing. Almost all segments of the computing industry, including file servers, workstations, desktop PCs and even CNCs have had an insatiable appetite for CPU horsepower. But, the demand for faster desktop PCs and their high volume use has fueled the rapid development of processors and made them economically feasible. Large file addressing on the other hand, is an issue in workstations and file servers where the bit issue determines the maximum number of files that can be addressed.

A lot of exciting capability is enabled by 64-bit processors. They are inherently twice as fast as their 32 bit counterparts, but there are other ways of gaining performance improvements making the performance issue not necessarily a critical reason to go to 64 bits. More important, however, is the address space improvement that 64 bits enables. A 32-bit computer can address, and work on, 2-to-the-32nd power bits of data at any one time. This translates to a file size limitation of 2 GB. A 64-bit computer on the other hand, can address and work on 2-to-the-64th power bits of data at any one time. That translates to 4 billion times more bits of data.

No one can deny that the capability of 64-bit processors is overwhelming, but there are transition issues that must be worked out before there can be widespread use of 64-bit processing at all levels of the PC environment. For example, Intel's first entry into the 64-bit processor will be the Merced, scheduled for sometime next year. Its first target will be the high-end server market which means the cost will probably be much higher than the general public will support for PC use. There are obviously other 64-bit processors that exist today but a second issue which impacts their use is the operating systems that support 64-bit PCs. Today, Windows 95 and Windows 98 do not support 64-bit computing and Windows NT provides only limited support on a special compiled version for workstations. Microsoft has promised to have an enhanced version of NT (anticipated to be version 5.0) available when Merced is released. It will incorporate 64-bit Very Large Memory (VLM) addressing, but NT's kernel and various programming interfaces will remain 32 bit for some time. This all leads up to the point that if CNCs are to stay PC compatible and remain low cost, they must also stay on 32-bit platforms.

When it comes to PCs and CNCs staying on 32-bit platforms there may not be a performance issue when you look at what Intel has planned. Intel is still positioning its 32-bit P2 family toward the mass market. Additionally, it is planning a next-generation 32-bit family targeted at the workstation market along with its 64-bit processors. This means that 32-bit processors and the necessary operating systems to support them will be with us for some time. Intel's CPU designers are ramping up production more quickly than expected, bringing low cost, higher clock rate, 32-bit chips to market. For example, between now and mid 1999, Intel will introduce to the market a wide range of new 32-bit processors. At the low cost end of the spectrum they will introduce a 300 and 333 MHz version of a 32-bit Celeron processor. In the Pentium II class, they will introduce a 32-bit Deschutes processor that starts at 333 MHz and a 32-bit 400 and 450 MHz version of Xeon processor, and a 32-bit 500 MHz Tanner processor.

Today's 32-bit PC based controls have the advantage of sharing low cost PC hardware and third party software. It seems most logical for CNCs to track this platform where the action is and move to 64-bit platforms only when they have become a solid part of the PC environment.