It is also one of the few methods for transferring molecular structure definitions between different programs. This experiment should ideally be performed on the Silicon Graphics computers. If you use a Macintosh, a program called MacX will start up, and following prompts, you will need to enter your SGI account and its password. MENU On a Macintosh computer, enter the line quest penicillin in the MacX window that appears, followed by TERM X11 MENU You will need to search the Cambridge crystal structure database for the penicillin and cephalosporin sub-structures. The first menu allows a molecule to be drawn.
Further clicks add a further atom to the last atom.
If you want the next atom not to be added to the previous, select MOVE first. To convert a single to a double bond, select DOUB, then MOVE and click on the bond desired. To convert a carbon to another atom on the menu, select the type from the screen menu and then MOVE before clicking at the desired atom. In this case they are sub-structures, but many other definitions are possible, including author names, formulae, etc. It is possible to combine several of these using logical operators.