Beginning this month, Apple is shipping Macs with an improved internal CD ROM drive, the AppleCD 300i Plus. The new unit offers a tray-loading feature similar to that found in home CD audio decks, eliminating the need for CD caddies. Over the next several weeks, all Quadra models with internal CD ROM drives will be modified to include the new drives. Future models will include the new drives as well.
Meanwhile, existing dealer and warehouse stock of the older units, containing the original caddy-loading AppleCD 300i, are likely to see price reductions aimed at clearing the way for the new models, so buyers who don't mind using the CD caddies are likely to find good deals. Model numbers for existing computers ending in "/A" include the old drive; the same part number with a "/B" instead indicates the new drive is installed. (This won't be true of new models.)
Tray-loading CD ROM drives have only recently become common in the personal computer industry, though such mechanisms have been the norm in the audio field since CD players became popular in the mid 1980s. The earlier tray mechanisms took up too much vertical space in drives designed for the tight spaces available in computer cases. Car CD players generally have a simple slide-in mechanism with neither a tray nor a caddy, and I hope to see these units in future CD ROM drives.