in 1982 in a joint venture with Toshiba. The "X" in all current TI-30 models refers to the addition of a 10+2 display (that is, a 10 digit mantissa plus a 2-digit exponent) in 1993; with the addition of a 2-line display and a D-pad in the XIIS/XIIB in 1999, the TI-30 line split in 2, with the TI-30Xa becoming TI's overall entry-level scientific, and the enhanced XII designs offering more input flexibility to the user. The MultiView models, introduced in 2006 and 2007, replace the 2-line display with a dot matrix display similar to a graphing calculator, and move many of the functions traditionally placed on or next to individual calculator keys off onto menus very similar to those used on the popular TI-83 calculator line. At one time or another, most models in the line since the introduction of the LCD models have been available in both solar powered and battery versions; the Xa retains solar power only on models sold in a few markets in Europe, while the XIIS and XS MultiView models run off both solar and battery power depending on available ambient light. The earliest model, however, uses a 9 volt battery, which is expected to last for approximately 20 hours of use, according to the Owner's Manual. However, two rechargeable kits were offered, the RK-1 and the RK-2, which each contained a battery allowing for two hours and four hours of continuous use, respectively, before needing to be recharged. TI-30 models TI-30 (1976): first version; LED display TI-30 LCD (1978): the first LCD version. European market only. In 1986, TI had a recall (at least in Germany) where they offered replacement due to (possible) defects. TI-30 replacement free of charge, or TI-31 Solar with 10,- DM payment. Other models replaced were the TI-55II, TI-35 and TI-57LCD. TI-30 II (1981): slimline format with the TI-30 key layout TI-30 III (1984) TI-30 SLR (1982): with Toshiba calculating chip. It had 9 digits of calculating precision. (US units had 11 digits at that time.) TI-30 SLR+ (1987): solar TI-30 Stat (1988): added basic statistical functions TI-30 Galaxy: part of a line of landscape format calculators from the mid-1980s TI-30X (1993): the X signifies an expanded 10 digit display (from the original 8). Switching to a new circuit board design introduced a logarithm bug. TI-30Xa (1994): added the constant key to the TI-30X TI-30Xa (rev 1996): introduced a