kdb123: Dflex2/4Rev. B and Dflex8 Rev. D Multiport Serial I/O Changes - Connect Tech Inc.
An enhanced Interrupt status port has been added. Some operating systems utilize a status port on non-intelligent cards to improve the Interrupt handling efficiency, some examples are SCO Unix and the COMi serial driver (OS/Tools Inc.) for OS/2. We have replaced the Status port buffering chip with a GAL (programmable logic device). By default we have preserved the compatibility of the status port with previous revisions, but customers can now order custom versions of the status port chip. Please contact Connect Tech customer support for more details regarding custom GALS.
A new jumper has been added, J2. This new jumper controls the functionality of the new status port. By default the jumper is NOT installed, this is the compatible with previous revisions mode. If the jumper is installed the custom status port mode is enabled. This jumper allows the user to use either a custom or standard status port, without altering the hardware or losing any backward compatibility. Technical support recommends that you not install the jumper, unless you are using a custom status port GAL.
The layout of the board has been redone. The board is physically smaller and is now routed as a four layer board.
The DIP package UARTS have been replaced with PLCC UARTS to save space.
None of these changes impact the compatibility with older revisions of boards. The new DFlex revisions are fully compatible with the previous revision.