First things first. This is not a "new" magic system. Been there, done that. It's a fun exercise, but this is different. I'm trying to describe a new way of looking at the mechanics. It's still the same system under the hood. I'm still using Spells Usable per Day, for example, just putting a different spin on it.
One more thing: this is written with Swords & Wizardry Core, 4th Printing in mind, although it is usable with any similar rules set.
Anyway, here goes . . .
Magic-users are called Scribes. Scribes know the ancient languages of magic, called the Eldritch Tongues, and use them to encode magical power and intent into scrolls. This is the only way magic is practiced. Technically speaking, anyone who knows at least one of the Eldritch Tongues can write spells to scrolls (known as encoding), and cast spells written to scrolls (known as pronouncing). The reality of such an endeavor is an entirely different matter.
The Eldritch Tongues
The Eldritch Tongues are all dead languages. They are very difficult to learn due to their intricate nature. Many subtle nuances of inflection and tone are required to control magical energies. The written language required to communicate such intricacies demands the utmost dedication from one who would master it. Scribes sacrifice the youth of their lives to just such an undertaking. Mastery of the lost languages of magic is not for the dabbler or casual student.
Scribes may use their "Max. Number of Languages" (pg7) to select Eldritch Tongues. Their are eight Eldritch Tongues, so no Scribe will know them all without some form of magical aid. However, knowing only one is enough to encode scrolls, and pronounce any scroll encoded in the selected tongue. Knowing a variety of tongues is useful for pronouncing scrolls discovered in musty libraries and lost temples. Such broad knowledge gives the scribe versatility.
Other classes may select one Eldritch Tongue at character creation. It requires four of their available language slots to do so. Such a character may pronounce any scroll encoded in the tongue they know. They may also encode scrolls in their chosen tongue, however time and material costs are both doubled. It is worth noting that locating spells to encode could be problematic (see Spellbooks below).
Table: The Eldritch Tongues (use d8 to randomize scrolls found in treasure)
It is possible that certain tongues are better suited to some spells than others. This is left for individual referees to determine.
Scribes maintain books of spells, from which to encode their scrolls. They are very protective and secretive about their spellbooks. They never allow other scribes to "thumb through" their spellbooks. They do not share spells. Rarely, and for great cost, will they sell one of their spells. Those strictures apply to other scribes. Scribes will never, under any circumstances, allow spells or spellbooks be in the possession of non-scribes. They will not sell, trade, or otherwise sanction such. If they come to know of a non-scribe in possession of spells or a spellbook they will pursue any avenue necessary to recover it.
The scribe must have the spellbook at hand in order to encode a scroll. The spell formula are far too complicated to memorize fully. A scribe without a spellbook is completely unable to encode scrolls. Spellbooks are also written in the Eldritch Tongues, so any spellbook found as treasure must be written a tongue known to the scribe to be of use.