Teenage Engineering's PO-33 K.O! is an 8bit sampler. 

I've had mine for a few months and am just now finding the free time to play with it.  The video is a first attempt at a loop using samples from the Atari 130XE.  The MP3 is the same set of patterns looped 6 times.  

atari8ko33 loop01.mp3

You may recognize where some of the samples are from. You may also want to see how many you can recognize before you read on.

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It was easier for me to record sounds from the Atari using a Digital Audio Workstation(DAW) and then trimming and splicing the samples before recording into the PO-33.

The first to be recorded was the drum set.  The program "Drum Synthesizer" from Antic Feb. 1985 provided the drum samples.  The drums were recorded then assembled into one track.  The PO33 recorded the drums and splits the track for playback. The breaks can be adjusted but PO33 seemed to work well enough.

The first two melodic sounds were recorded from the program "Musical Atari Keyboard", Antic August 1983.  This keyboard has the option of defining a decay rate for the note.  Sound 1 and 2 were recorded with decay rates of 0.8 and 0.5.

The rest of the 6 sounds were produced from recorded tracks of Star Raider, Missile Command, Frogger, Pac-man, and Q*bert.  Recording a quick play of the first level provided a number of familiar sounds.  Again,  I found that selecting short sections of sound on the tracks and recording on the PO33  and  was easier then trimming them on the PO33. 

Once the sounds were in the PO33,  it was just a matter of creating a couple of catchy patterns and recording the loop back into the DAW.