Support element has to be more or less full-blown computer as the mainframe itself does not have any real firmware to boot^H^H^H^HIPL itself. Before support elements the IPL process involved initalizing various things by toggling switches on the console.
Also why the mainframe would even have a framebuffer?
Providing a console interface (ie. 3270 terminal emulator) to whatever OS runs on the mainframe is only small part of what SE does.
> Also why the mainframe would even have a framebuffer?
The mainframe itself wouldn't, but it might be running a VM that has one (and also has reserved capacity on the system, preventing other tasks from fighting it for priority.) I was picturing the support element as simply a physical extension of that VM, sort of like x86 VMs can use IO-SRV to lay claim to graphics cards and such. It'd be like the BMC on an x86 server motherboards, but virtual.
What you say about the support element also being used to IPL the system makes sense, but I'm surprised that responsibility is pushed into such a fragile component as a laptop. Why not just make the "IPL booter" a single-responsibility SoC card-edge daughterboard (I'm picturing a game-cartridge-looking thing), and leave the support element for, well, support?
Just a word of caution for anyone reading this. I highly discourage anyone from actually learning ^w. I learned it, then had to forcefully un-learn it when I kept accidentally closing tabs on my browser, other people's browsers, my file manager, etc. etc. ad nauseam. Don't make the same mistake I did, just press backspace a lot. I know life is short but the sudden rage of having unexpectedly closed a tab is just not worth the added efficiency. I am passionate about this subject; however, I mean no disrespect for those who have (somehow) managed to use ^w productively.
Also why the mainframe would even have a framebuffer?
Providing a console interface (ie. 3270 terminal emulator) to whatever OS runs on the mainframe is only small part of what SE does.