Here’s the BOSS JS-5 JamStation, discontinued in 2004. This thing can do a lot. You can play along with preset accompaniments or create new ones with your own arrangements. I used it mostly as a glorified metronome and practice tool. For the solo-giggers, you can program fully accompanied songs with drums/bass/keys, to play live with. If thats what you're going for, this gets you there - without having to haul a laptop to gigs.

The beauty of the JS-5 is in its utility. Once you orient yourself, it’s relatively easy to use. Some menu-diving but mostly hands-on tweaking with controls and buttons, laid out with good UX in mind. The included sounds are very hi-fi.

This unit is in great shape. Some light signs of use and almost mint. I just replaced the internal battery and serviced it. It has a long life ahead. It works as new. 

Includes the power supply and original manual, but no box. This sale does not include a SmartMedia card. For added storage, it accepts SM cards up to 64MB.

This unit HAS onboard memory, including 200 preset accompaniments and 100 slots to create your own arrangements (with the sounds/rhythms/effects/etc included). The onboard memory was more than enough for my needs.

JS-5 description from BOSS (copy/paste into a new tab): boss.info/global/products/js-5/

I will package and ship with care. 

Thanks for looking and let me know if you have any questions.