On 3/10/2016 5:45 AM, David Crayford wrote:
We're building a new product which will have several UI's; ISPF, Web, Eclipse etc. For the ISPF we're wondering how we should optimize the screen real estate for todays customer.
While interesting, the results of this survey really should not matter to anyone developing a modern application with a 3270 interface.
There are three 3270 addressing choices: 12-bit, 14-bit and 16-bit. 12- and 14-bit addressing are fully self-describing (i.e., you can inspect the buffer address itself to know which addressing scheme is in use), so many products with 12-bit legacy heritage limit themselves to 14-bit addressing. Unfortunately, this includes ISPF -- for now.
If you're starting from scratch, then there's really no reason not to support 16-bit addressing. TSO/E does, SMCS consoles do, many of our products do, etc. There's almost no extra work involved to provide support for all terminal sizes.
You simply maintain one bit in your "terminal control block" to indicate that 16-bit addressing is in use. (You learn this from the Read Partition-Query response.) If that bit is on, buffer addresses are 16-bits wide. If it's off, you can fall-back to the buffer address inspection method i.e., if the top two bits are zero, you're dealing with a 14-bit address; if non-zero, you are dealing with a 12-bit address. It's really just that easy...
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