I was reading a book on digital electronics and the gates with more than two input are drawn differently. I have seen many books that draw schematic in this style. I was wondering what software did they use. I am specifically talking about the way the OR gate is done here.
That doesn't look like any software was used, but a good old-fashioned drawing board, maybe a few symbol templates/stencils/curve templates used by someone who probably is a trained technical draughtman.
Making such drawings is a job where you actually needed quite some expertise, so technischer Zeichner (at least in Germany) is a proper Ausbildungsberuf (a recognised occupation requiring formal training).
Nowadays, you'll find a lot of circuit drawing software, but my guess is that you'd need to extend them quite a bit to make it easy to draw such legacy diagrams.
Other than that, standard vector graphics software can be used to draw anything that primarily consists of geometric elements.
As others have said, they probably didn’t have any particular software available at the time of publication. If you are interested in a modern solution, however, check out the Circuit macros package for LaTeX. It has the wide gate in its library. From the manual:
I don't believe this was drawn with any modern software tool. It appears to me to be a reproduction from a late-80s/early-90s era databook from before the days of online/digital datasheets. Go to ti.com and look up some of the CD4000-series logic datasheets that are reminiscent of this period. Dual 2-Input NAND
As to the "wings" on the OR, this is typically done to allow the user to better follow the interconnect of the wires by spacing them out.