perhaps what you should do in asking a question such as this is provide more information about what you require, both in speed and in I/O capability. Several fellows have suggested serial I/O to external hardware. Without knowing what the update performance requirements of your external I/O are, it's hard to say whether that will meet them.

First of all, you can still buy 82C55's in moderate quantity. A Google search will support that. Additionally, you can pretty easily create an equivalent circuit fast enough to interface with the fastest MCU's in low-cost CPLD's, as has been amply pointed out already.

I'm pretty familiar with the single-cycle chips, and they don't all have to run at full speed all the time. Since your device is external, you can adjust the external cycle length to accomodate an external device.

Another alternative, however, would be, simply, to place 805x IP in an FPGA and integrate it there with the precise hardware you need, in a package that accomodates your I/O pin count requirements. You can do this with free IP or you can purchase an appropriate IP license. By choosing an appropriate combination of FPGA technology and IP, you can achieve a nearly arbitrary level of performance. It depends mainly on how much cost you can tolerate.

There's free IP for parallel I/O, too, and, in fact, you can build your own parallel I/O without some of the restrictions and limitations of the 8255. You may find this a much more pleasant path to a suitable solution.

RE