Modern Digital Electronics by R. P. Jain is a definitive textbook for engineering students. You can access a version of this text on Google Drive or through the Google Drive Link on Docs. The Story of "Modern Digital Electronics"
Some universities upload scanned copies of sections or previous editions for internal student use. Search for: r p jain digital electronics pdf google drive
Google Drive links are often set to "View Only" by the original uploader. If the copyright holder submits a DMCA takedown request to Google, that link dies instantly. You might download half the book, only to find the rest missing or the file deleted when you need it for exam revision. Modern Digital Electronics by R
Institutional Repositories: Some academic sites host chapters or the full text for student use, like this full textbook copy from Dronacharya College. You can access a version of this text