Speaking of saves, 5e lets you attempt saves every turn. Not so in AD&D, and you didn't have concentration either.
AD&D had plenty of caster concentration aspects in spells. Lots of things break concentration but there are some things you can still do while concentrating.
"As soon as the cleric
ceases concentration, the spiritual hammer is dispelled."
"The illusion lasts until struck by an opponent — unless the spell caster causes the illusion to react appropriately — or until the magic-user
ceases concentration upon the spell (due to desire, moving, or successful attack which causes damage)."
"The elemental conjured up must be controlled by the magic-user, i.e. the spell caster must concentrate on the elemental doing his or her commands, or it will turn on the magic-user and attack. The elemental, however, will not cease a combat to do so, but it will avoid creatures when seeking its conjurer.
If the magic-user is wounded or grappled, his or her concentration is broken. There is always a 5% chance that the elemental will turn on its conjurer regardless of concentration, and this check is made at the end of the second and each succeeding round."
"The spell caster can maintain the illusion with
minimal concentration, i.e. he or she can move at half normal speed (but not cast other spells)."
"Unless combat is spell versus spell, many such attacks will happen near the end of a melee round. This is because the spell requires a relatively lengthy time to cast, generally longer as spell level increases, so high level spells may take over a full melee round to cast. Furthermore, if the spell caster is struck, grabbed, or magically attacked (and fails to make the requisite saving throw — explained later), the spell will be spoiled and fail. Spell combat includes cleric and magic-user, as well as monster-oriented spells. Curative spells are handled likewise."
"SPELL CASTING DURING MELEE
These functions are fully detailed in PLAYERS HANDBOOK. Their commencement is dictated by initiative determination as with other attack forms, but their culmination is subject to the stated casting time. Both commencement and/or completion can occur simultaneously with missile discharge, magical device attacks, and/or turning undead. Being struck by something during casting will spoil the spell.
Spell-casters will always insist that they are able to use their powers during combat melee. The DM must adjudicate the success of such use. Consider this: The somatic (movement) portions of a spell must be begun and completed without interruption in a clean, smooth motion. The spell as a whole must be continuous and uninterrupted from beginning to end. Once interrupted, for any reason whatsoever, the spell is spoiled and lost (just as if used). Spells cannot be cast while violently moving — such as running, dodging a blow, or even walking normally. They are interrupted by a successful hit — be it blow, missile, or appropriate spell (not saved against or saveable against).
Thus,
casting a spell requires that a figure be relatively motionless and
concentrating on the effort during the entire course of uninterrupted casting. For example, a magic-user casting a fireball must be in sight of the intended area of effect during the course of the spell (although an associate could be there to open a door intervening between caster and target area at an appropriate time — provided the timing was correct, of course). The caster cannot begin a spell, interrupt it just prior to completion, run to a different area, and then complete the spell; interruption instantly cancels it. Unless a spell has no somatic components, the caster cannot be crouching, let alone prone, during casting.
It can thus be understood that spell casting during a melee can be a tricky business, for a mere shove at any time can spoil the dweomer! Any spell can be attempted, but success is likely to be uncertain. Use the following procedure for spells cast during melee:
1. Spell casters must note what spell they intend to cast at the beginning of each round prior to any knowledge of which side has initiative.
2. Attacks directed at spell casters will come on that segment of the round shown on the opponent’s or on their own side’s initiative die, whichever is applicable. (If the spell caster’s side won the initiative with a roll of 5, the attack must come then, not on the opponent’s losing roll of 4 or less.) Thus, all such attacks will occur on the 1st-6th segments of the round.
3. Intelligent monsters able to recognize the danger of spells will direct attacks against spell casters if not engaged by other opponents so as to be prevented from so doing.
4. The spell caster cannot use his or her dexterity bonus to avoid being hit during spell casting; doing so interrupts the spell.
5. Any successful attack, or non-saved-against attack upon the spell caster interrupts the spell.
Because spell casting will be so difficult, most magic-users and clerics will opt to use magical devices whenever possible in melee, if they are wise."