The ШахматныЙ Партнер (which translates as Chess Partner in English), the Elektronika IM-29, was manufactured in 1992 at the Svetlana factory in St Petersburg, Russia. The Chess Partner is a very close copy of the Mattel Computer Chess. In some ways a strange choice for ‘cloning’ dating as it does from 1980, some twelve years previously. Therefore the Mattel is a much weaker, feature limited and trickier to use handheld chess computer than many later models which could have been chosen for copying. Perhaps by 1992, coming out of the Soviet era Russian manufacturers were more restricted by copyright law and therefore chose an easier and older cloning target in legal and technical terms?
Whatever the logic the IM-29 was produced and in a strange form. What the Mattel had going for it was a compact all-in-one format using batteries, with the LCD screen replacing the need for a board and fiddly chesspieces, which means it was a highly portable pocket-sized handheld. The first portable with a LCD display. Unless you count the much larger heavier Super System III with battery pack. However use of the IM-29 with batteries is compromised by the pcb which intrudes into the ‘Mattel’ battery compartment space (see photos below). So the IM-29 has a DIN socket for its own mains power adaptor.
In other respects the IM-29 is a very close copy of the Mattel with only minor manufacturing differences, and colour and language differences distinguishing the two. On playing the two machines side-by-side I did not notice any significant differences in play, though it will take much more testing to be sure that the Julio Kaplan/Craig Barnes program in the Mattel was ported exactly as it was to the IM-29. Neither machine has an opening book.
The technical details for the Mattel are - INS8050 8 bit singlechip processor running at 6 MHz, with 4KB program ROM and 256 byte RAM.