"I know I wrote it down somewhere!"

Brainstorming ideas for making wussy wizards in old-school dungeon crawls less miserable to play / a better part of the group dynamic...

Instead of having to memorise all spells, you can cast spells from your spellbook - at least, those with a reasonable casting time that don't require a zillion components or anything. However, this is awkward, occupies both your hands, and limits your ability to defend yourself or see trouble coming, so you probably need someone to cover you. As well as reading a spell aloud being slower than casting from memory, there's also the time required to flip through pages in your spellbook trying to find the right spell.

Which in a computer game situation could lend itself to a game in which you play the wizard, the rest of your party is your hired minions that you order around, and turning spellbook pages takes a round, so the strategy of how you've organised your spellbook before the fight is relevant.

"A wraith? Dammit, why didn't I put a bookmark in front of the On Matters Of Undead section?"

"... note to self, next time put the 'Banish Demon' spell next to the 'Summon Demon' spell, just in case..."

If you go further along the line of being brilliant and in charge of all these goons, then minions might have basic AI (which can be tweaked in dialog between fights) but if you want them to do something particularly clever in a battle you have to spend your round yelling commands.

"No, backstab the hobgoblin! The hobgoblin!"