I have one of these, too, a model from 1992. They're interesting since they've got persistent memory and programmability and also used to have expansion cards(!

I have one of these, too, a model from 1992. They're interesting since they've got persistent memory and programmability and also used to have expansion cards(!) which are very rare nowadays. However, programming them is rather complicated, you have to literally count bytes and enter the correct offsets. You can get these interesting machines new from Ukraine for about $20 on Ebay (with condensators fixed, which tend to go bad after so long time). Be aware that the keyboards tend to mushy and are not high quality, though.