Most trade magazines of that era were pretty similar in size and number of ads , eg. PC Magazine. Pre-Internet they were one of the only ways to keep up with industry news, topics and products.
There were, and still are, a number of magazines in the electronics industry, EDN, for example, that were available for free to engineers that were 75% ads with a few articles. The publishers and advertisers expected the articles to draw the engineers who would be the ones to spec components for their current designs.
Then there was computer shopper...man I'd get 8 months out of one of those just paging through and dreaming