D&D General Mechanical differences between AD&D and Basic?

[Mannahnin]

Correct but not complete.

It HAS such a rule, even if it was officially optional. Where Basic didn't have one at all.

 

[rogueattorney]

On that .... not exactly correct.

D&D 5E - The -10 Myth: How a Poorly-Worded Gygaxian Rule Became the Modern Death Save

This is a little different; normally, I like to make certain I have my ducks in a row for a thesis, so that other people can shoot them down. It is the internet! However, I'd like to explore a concept I've been thinking about that popped up in a recent thread. @Lanefan wrote the following in...

www.enworld.org

How is it not exactly correct? The 1e DMG had the optional negative hit point rule, which was - at least in my experience - broadly adopted by most 1e players. 1e also had - as I stated in my previous post, but which you edited out - clerical healing spells available for first level clerics - as many as 3 CLWs for clerics with high WIS. Also, characters with more hit points - fighters had d10 instead of d8, clerics had d8 instead of d6, thieves had d6 instead of d4. A couple of the classes that weren't available in Basic, rangers and monks, started at first level with 2HD. So, in sum, 1e was more forgiving at low levels than B/X was.

 

[Snarf Zagyg]

Correct but not complete.

It HAS such a rule, even if it was officially optional. Where Basic didn't have one at all.

Well, the issue when discussing Basic is that the RC introduced a lot of additional and variant rules.

For example, the RC has the first example I know of for the death saves we see in 5e-

There's a variant rule that when a PC is reduced to 0hp or below, they make a death ray save every turn (10 minutes). Fail one and you die. But if you get magical healing or are tended by someone with healing skills, then you'll live.

I know! I think the minutiae in the RC is only exceeded by the DMG.

 

[Snarf Zagyg]

How is it not exactly correct?

Maybe if I wrote a very long post explaining my position, it might help?

Oh ... nevermind. Carry on!

 

[rogueattorney]

The term THAC0 first appears (in an official book, at least) in the monster statblocks appendix in the back of the 1E DMG. I think I remember hearing that Rob Kuntz was responsible for that. Of course, it wasn't "true" THAC0 as the combat matrices in the DMG had the repeating 20s, so I think you're correct that THAC0 as a mechanic was first really introduced in the Tom Moldvay-edited 1981 Basic set.

THAC0 was not introduced nor even mentioned in the B/X Moldvay/Cook rules. The B/X rules had the same repeating 20s that 1e did.

The OD&D Monsters & Treasure Assortments from 1977 had an "attack value," which was what we might call a "THAC9" as it was the number to hit armor-less opponents, which in OD&D was AC9 and that was the first attempt to move away from the charts.

The 1e DMG famously had its "To Hit A.C. 0" number in its monster listings, which was a helpful tool rather than a rule as it didn't work against better ACs due to the aforementioned repeating 20s.

The term "THAC0" started appearing in late 1e products, again as a helper or mnemonic rather than a rule. THAC0 didn't actually become the rule until 2e came out in 1989. THAC0 was then mentioned in the Rules Cyclopedia (1991), but confusingly, was still being used in the 1e fashion due to still having the repeating 20s.

I have a way-too-long and boring essay on the history of AC and the to hit charts from OD&D to 2e if anyone is really interested.

 

[Nikosandros]

I have a way-too-long and boring essay on the history of AC and the to hit charts from OD&D to 2e if anyone is really interested.

I am

 

[rogueattorney]

I am

You asked for it...

At some point between the publication of Chainmail miniature rules (1971) and the original Dungeons & Dragons rules (1974), the various armor types were assigned numbers 9 through 2. Nobody really remembers why those numbers were used. Supposedly it was from a naval warfare game. The theory I like best is that it was that number or less needed to roll to hit with 2d6.

Regardless, by the time of the original D&D rules, the Armor Class number really functioned only as the label at the top of the to hit chart and could have been anything - 1 through 8, A through H, whatever. It was a signifier of a specific armor type. AC 5 always meant chain and no shield. Dexterity did not affect the opponent’s ability to hit, and things like magic armor and so on didn’t change ones’ AC; it modified the opponents’ to hit roll. Thus, a guy in plate mail with a +1 shield still had an AC of 2; his opponent just had a -1 to his to hit rolls. (Also magic shields and magic armor didn’t stack; you took the best option of the two If you had +1 armor and +2 shield, your opponent only had a -2 to hit, not -3.)

The Greyhawk supplement (1975) changed the rule to make magic armor affect AC (and for magic shields and armor to stack), but instead of expanding the to hit chart, made an AC lower than 2 an addition to the score needed to hit AC 2. In other words, any AC below 2 didn't create a new column on the chart, but created a penalty to hit. It also introduced monsters with ACs out of the normal range of 9 to 2. Further, it introduced the rule of high dexterity reducing an opponent’s chance to hit, but only for fighters, and it was explicitly a “to hit” penalty and not an AC bonus.

For the next few years, adjustments to AC were treated inconsistently and more and more monsters with AC lower than 2 were introduced. Swords & Spells miniature rules (1976) had charts going down to AC -2. The Holmes version of Basic (1977) had no Dexterity adjustment to hits, had a chart running from 9 to 2, and went back to the rule that magic armor adjusted opponent’s to hit rolls instead of AC.

The AD&D PHB (1978) first introduced dexterity as a bonus or penalty to AC, expanded the range of normal AC to include an AC 10 (shoving the new AC column into the middle of the chart between Leather and Chain), introduced the distinction between Armor Class and Armor Type, reiterated Greyhawk’s rule that magic armor affected AC instead of the "to hit" roll, and introduced a bunch of new kinds of armor to buy with overlapping armor classes. The effect was that whereas before "AC 5" always meant Chain mail, now there were any number of different combinations of armor and dexterity bonus/penalty that could result in someone having AC 5.

The AD&D DMG (1979) took another few steps to varying ACs by specifying that spells and other magic effects didn’t affect opponent’s to hit rolls, but rather changed the affected party’s AC, and gave a number of cases where AC bonuses/penalties from dexterity didn’t apply. It also introduced magical armor other than plate mail - before there was no magical leather or chain. It had to hit charts running from 10 to -10, and added the additional complication of non-linear to hits - the 5 repeating 20s.

So the transition of AC from 1971 to 1979 was from a static designation of a limited number of 8 specific armor types on a linear "to hit" chart, to a frequently changing number that could signify many different combinations of armor and abilities that would slide up and down a non-linear chart depending on the situation.

The Monster & Treasure Assortment (1977) first introduced an attack value stat in its monster stat blocs. This was called “attack level” or “AL” and was what we’d now call THAC9. That is the number needed to hit AC 9 which was at that time the AC for humans with no armor. The DMG (1979) had a similar big list of stat blocs and had a stat called “To Hit A.C. 0.” Because of the repeating 20s, this was a reference and not a rule. You couldn’t necessarily add negative ACs to that number and get the right to hit amount. Especially for smaller monsters and lower leveled characters. If you didn’t memorize where those repeating 20s were, you still had to go to the chart.

I also think it was an indication that - at least as intended by the author - negative armor classes were supposed to be vanishingly rare.

The 1981 Basic and Expert rules adopted AD&D’s rules with respect to dexterity and magic armor affecting AC. It had to hit charts running from 9 to -3. It didn’t have numbers beyond 20 on the to hit chart because it had a rule that a result of 20 always hit. The Expert rules (1983) changed things up by reintroducing the 5 repeating 20s from AD&D and stating that a roll of 20 only hits if the chart indicates a 20 or less is required to hit. Thus, 20 was no longer an "auto-hit." The Companion rules (1984) had "to hit" charts going to AC -20 and said that AC had no limit and could go beyond the charts. The Master rules (1985) expanded the "to hit" charts to from 19 to -20, had five repeating 2s on the high end like the repeating 20s on the low end, and expressly adopted the AD&D rule that defensive effects change the AC and not the attacker’s to hit roll.

In 1989, 2e AD&D came out. It dropped the "to hit" charts and turned ThAC0 from a reference into the rule. Completely linear - subtract AC from THAC0, that’s what you need to hit. It didn’t matter whether an effect modified a to hit roll or AC, it all worked out in the wash. This is where AC completely turned away from a designation on a chart to a variable in an equation. This is where subtracting a negative number really became a thing because negative ACs now meant, "Do math," and not, "Look at the chart."

The Rules Cyclopedia came out in 1991. It confusingly adopted the THAC0 nomenclature, while retaining the nonlinear chart from the Master rules. So not only were you subtracting negative numbers, that process wasn’t even guaranteed to give you the right answer.

The important thing to remember with both 2e and the RC is that they weren’t ground-up new systems. They were revisions of existing systems designed to be as backwards compatible with the previous products as possible. In that regard they were successful. You could still pretty easily use products that came out in 1977 with these rules that came out in 1989 or 1991. Plate Mail and Shield is AC 2 in every D&D product from 1974 to 1999. It’s just that the change in how Armor Class worked (from static and discreet to variable and infinite) was a real pain in the ass.

 

[Snarf Zagyg]

@rogueattorney
You might want to consider updating your post with some of the additional research and work done by Jon Peterson and others, showing the influence of certain groups (such as those at UCLA) in the development of THAC0.

Source:

To Hit Armor Class Zero

The die roll value required for an attack to hit an armor class of zero, or "THAC0," is the signature combat mechanism of the second edit...

playingattheworld.blogspot.com

EDIT- the comments, as always, are fascinating. Notice Schick "confessing" to adding the "To Hit AC 0" column to the DMG. Heh.

 

[teitan]

On that .... not exactly correct.

D&D 5E - The -10 Myth: How a Poorly-Worded Gygaxian Rule Became the Modern Death Save

This is a little different; normally, I like to make certain I have my ducks in a row for a thesis, so that other people can shoot them down. It is the internet! However, I'd like to explore a concept I've been thinking about that popped up in a recent thread. @Lanefan wrote the following in...

www.enworld.org

I was wondering what 1e he was talking about for a second

 

[Mannahnin]

Well, the issue when discussing Basic is that the RC introduced a lot of additional and variant rules.

For example, the RC has the first example I know of for the death saves we see in 5e-

Sure. The RC, in 1991, did add some more rules that weren't in Basic at all. Rogueattorney was talking about B/X, though.