Open your preferred digital audio workstation, such as Pro Tools, Cubase or Logic. Depending on your interface preferences, a new session or the last saved session will open automatically. If you want to start a brand new track, click "File" and select "New." If you want to add the bass slide to a work in progress, click "File" and select "Open Recent."
Connect a MIDI controller to your computer with a USB cable. The MIDI controller sends data commands to your computer, telling the digital audio workstation which notes to create. If you don't have a MIDI controller, some programs permit you to use your typing keyboard as a MIDI input device. For example, if using Garageband, click "Window" and select "Musical Typing."
Open a new MIDI channel. The exact command sequence varies according to program, but you typically click an icon on the channel strip. Alternatively, click "File" and select "New Track" from the drop-down menu. By selecting MIDI, as distinct from audio, you assign the MIDI protocol as the primary input method.
Double-click on the MIDI channel to name it.
Open the instruments menu and select your preferred bass sound. Typical options include "Plucked Bass," "Double Bass" and "Electric Bass."
Select a tempo. The typical default tempo for a new session is 120 beats per minute (BPM). Increase or decrease the tempo by altering the figure in the Beats Per Minute box. Audition a variety of tempos until you find one that suits you.
Click the "R" icon on the channel strip. This makes it record-ready.
Click "Record" and play the sequence of notes to be included in the slide. In real-time, this won't sound like a slide as the notes will have a distinct stepped sound.
Open the "Piano Roll" interface. This is a universal MIDI-editing interface that represents the notes on a virtual piano keyboard.
Highlight all of the notes, click "Tools" and select the "Glue" tool. This tool is typically used for undoing trim edits and joining separate notes together. By gluing the notes together, the attack of the note becomes muted so each ascending note blends into the one before, approximating the glissando sound of a bass slide.