TL;DR
Let's say that computers were invented at a school for the blind in mid-1800s. How would today's technology, based on these non-screen-based computers, be different?
ETA: To clarify and hopefully narrow this enough -- I'm assuming that both the newer products will be influenced by functional computers predating movies & television: radio & telegraph/telephone may be more of the communication models. Also, that just like numpads on phones and computer keyboards are arranged differently due to vestigial bits from their separate origins, and our "Save" icon may confuse those who hadn't grown up with 3.5" floppies (I'm from the 5.25" era myself - Apple //c!), and we still call that thing in a car a "glove compartment" despite not wearing specific driving clothing any more).
So while sighted potential users greatly outnumber the blind ones, they're from a world where computers have always been fully accessible to the blind (so accessibility is not an afterthought), and that has probably driven the development of the CS field for quite a while.
Background elements
Braille had already been invented by the early 19th century, and it was derived from a military application (Night Writing, for Napolean's army) -- much like our computers (stored programs, some of the more theoretical elements were codified during WWII ) https://en.wikipedia.org/wiki/Braille
Punch Cards for Weaving had been invented in 1803 -- for a while schools for the blind were often trade schools-- the first one (https://en.wikipedia.org/wiki/Institut_National_des_Jeunes_Aveugles (first school for the blind was also named "National Institute of the working blinds", and was famous for graduating Organists.)
So now let's say they got an early Jacquard Loom head type machine (instead of Organs) from https://en.wikipedia.org/wiki/Jacquard_loom#Importance_in_computing
... The ability to change the pattern of the loom's weave by simply changing cards was an important conceptual precursor to the development of computer programming and data entry. Charles Babbage knew of Jacquard looms and planned to use cards to store programs in his Analytical Engine. In the late 19th century, Herman Hollerith took the idea of using punched cards to store information a step further when he created a punched card tabulating machine which he used to input data for the 1890 U.S. Census.
(Note that this Loom appears to also be a French invention.)
Charles Babbage & Analytical Engine - according to Wikipedia (sorry that I keep going back to that source, but I'm assembling fragments of things I thought I knew or picked up (I'm no tech historian), and Wikipedia's the easiest place to assemble the threads.) -- he was self-taught from reading many mathematicians, some of which were French, and was definitely fighting the British Establishment.
from https://en.wikipedia.org/wiki/Charles_Babbage#Computing_pioneer
While Babbage's machines were mechanical and unwieldy, their basic architecture was similar to a modern computer. The data and program memory were separated, operation was instruction-based, the control unit could make conditional jumps, and the machine had a separate I/O unit
So a computer doesn't need to be print-derivative
We have punched cards (tangible, non-alphabetic) manipulating rules and representations of numbers. As Ada Lovelace said:
"We may say most aptly that the Analytical Engine weaves algebraical patterns just as the Jacquard loom weaves flowers and leaves."
So what if punched cards went in, braille results came out? Things may have stayed mechanical longer, instead of moving to processors as we know them, but there'd also be almost a century's extra progress. "Screens" may have moved to Refreshable Braille Displays - but would there be "windows" and other simultaneous processing?
The "World Building" or AltHistory part --
Just like the Internet was very US-focused in the beginning, so it has some legacy effects on domain names and rules, perhaps in this world, the computer world (and thus internet?) were dominated by French research, and blind computer scientists. Look at the Minitel for an example of France being way ahead of the curve! They started as phone-book replacements, but provided message boards and finance stuff.
why I'm asking
I'm documenting navigation of applications designed with minimal concern for accessibility. My particular job seems to be describing how to navigate web applications for screen readers. Screen Readers (which read aloud text to blind/low-vision computer users) address everything in a pretty linear way. (Also, we have to keep all navigation keyboard-focused -- it's more predictable than a mouse.)
When windows pop-up, where did the focus go? Do the users know there's a new dialog on screen? Where does the focus go when the error message goes away? (To the last place it was, to the line with the error, or to the top of the page?) It's easy for the sighted to notice a missing field, the blinking cursor, or that something changed on the screen: but if the default were audible and tactile? How would the interfaces change?
What different communication elements may be emphasized? Would casual computers (like cell phones) do the same things or different ones?
I know answers could go in a steam-punk way, but they doesn't have to, or the proposed tech doesn't need to stay that way.