Wacom worked very closely with Apple to get the necessary tablet support into OS X, and released its driver the same day that OS 10.1 became publicly available. There were many challenges that Wacom had to work through with Apple to get it all working, and this was the soonest date that tablet support was possible.

There are a number of reasons for Wacom's decision to not support ADB & serial tablets on OS X, most of which originate outside the realm of influence of Wacom:

(a) Apple's leadership and direction
Apple is an early leader in the move away from "legacy" connectivity. Wacom has worked closely with Apple to provide USB tablet functionality on OS X, however Apple is not prioritizing efforts towards legacy support. Apple has made clear to Wacom that any issues that arise related to OS X support for legacy (ADB or Serial) tablet connectivity will not be supported by Apple. Based on past experience, USB tablet support for OS X was impossible to achieve without specific support from Apple and the updates they implemented for USB tablet support in OS X version 10.1. The protocol and tablet communications requirements under OS X are different from OS 9 and intervention by Apple would be required to achieve support for Serial or ADB tables. Due to these reasons Wacom will focus future development efforts on providing the best possible USB tablet support for OS X. Wacom will continue to provide support to user’s of ADB and Serial tablets on legacy operating systems only.

Note: Apple did specifically add ADB mouse and keyboard support into OS X. Apple only added ADB support for standard devices. Apple added no support for non-standard device protocols, including pen tablets, many digital cameras, and many other input and output devices.

(b) Reliability and support problems of ADB and serial adapters
Most users that use ADB or serial tablets on a newer Mac do so through some sort of USB adapter. Wacom finds that these adapters pose many problems even under OS 9 - although they work well for many users, adapter problems are nevertheless one of the biggest reasons for Tech Support calls. For example, an adapter may work fine on OS 9.1 but will fail to work after an upgrade to OS 9.2 on some Macs. All such occurrences are a frustration and delay for our customers who cannot use their Wacom tablet until they find a new driver for their adapter, or some other solution. Since many tablet users end up calling Wacom with their adapter problems, this further represents an ongoing burden for Wacom's development and Tech Support (free to all customers).

(c) Data rate limitations of ADB adapters on OS X
Commercially available ADB-to-USB adapters (like the Griffin iMate) are low-speed USB devices. For them to work with a Wacom tablet on OS 9, they essentially push the limits of the low-speed USB interface by sending data at a rate that exceeds the low-speed USB specification by more than 10%. This works reasonably well in Mac OS 9 because OS 9 does not enforce data rate limits on low speed USB devices. During the development of the OS X tablet driver Wacom found that OS X is a lot stricter about enforcing interface specifications at all levels. Wacom is therefore convinced that OS X will not accept the excessive data rate of these ADB-to-USB adapters. At the same time, Apple has clearly indicated that they will not resolve any OS level issues regarding support for serial or ADB issues. It is even less likely for Apple to resolve this issue because it would require the OS to violate the very specifications that were implemented to assure its stable operation. So OS X will not accept the necessary data rate from the "overclocked" ADB-to-USB adapters and these devices will therefore not work on OS X.

(d) Performance problems of serial-to-USB adapters
Most serial-to-USB adapters are optimized for use with modems (Keyspan offers the only serial adapter that works o.k. with tablets under OS 9). They collect a number of data packets and then send them all at once. This helps the adapter to minimize the number of USB calls and to speed up data throughput for a modem - but it really cripples the tablet performance. Since the tablet data is sent in irregular intervals, the screen cursor gets updated in irregular intervals as well. Rather than smooth movements, users see very jerky behavior as the screen cursor pauses and then catches up with the next set of data packets passed along by the adapter. This performance is not acceptable, and implementing driver support for it does not make sense.

(e) Negative implications for all OS X tablet users
USB offers support for hot-plugging, which automatically unloads or reloads the device drivers as the USB devices are unplugged or re-connected. This means the computer does not have to run drivers for disconnected devices and there is less potential for conflicts with unplugged devices. These benefits disappear when ADB and serial tablets are supported, because the older technology does not support hot-plugging and requires the driver to be loaded and running at all times (whether the user has a tablet with adapter or a real USB tablet). So the addition of ADB or serial tablet support would have significant negative consequences for ALL tablet users on OS X.

(f) Long-term considerations
USB is the future. It makes sense for Apple, Wacom, and our mutual customers to focus on optimized USB integration for OS X. The USB tablet integration effort has been a huge effort for both Apple and Wacom and Wacom is pleased to currently offer USB support for OS X (10.1) with significant help and support from Apple. Attempting to add support for older tablets through adapters would pull away Wacom's resources from updating the driver for ongoing new releases of OS X and from assuring high quality functionality for USB tablets. Therefore, the decision to not support ADB and serial connections on OS X is best for everyone - for customers, for Wacom and for Apple.

For customers planning to continue using a serial or ADB tablet on an older computer, Wacom suggests not upgrading the operating system to OS X. Wacom understands that this may be disappointing news for some users of older tablets and appeals to all customers' good sense. Technology progresses continuously and it is this same progress that brings us the always new and better standards and products that we look forward to - including OS X itself. While this may not be the answer that they were hoping for, Wacom hopes that these details make it easier for its customers to understand and accept the situation.

- Product Management