In its final incarnation, Belle was composed of a PDP-11/23 with a LSI-11 processor and many custom boards. There were three custom boards for move generation, four custom boards for position evaluation, and one board with custom microcode which controlled the whole thing. The computer also had one megabyte of commercial memory which was used for transposition tables. At the end of its career, Belle was donated to the Smithsonian Institution. The overall architecture of Belle was used for the initial designs of ChipTest, the progenitor of IBM Deep Blue.
In 1982, Belle was confiscated by the US State Department at Kennedy Airport when heading to the USSR to compete in a computer chess tournament; its shipping was considered to be an illegal transfer of advanced technology to a foreign country. It took over a month and a $600 fine to get Belle out of customs. Thompson learned that the reason for confiscation was the attached HP 2640 terminal which had internal VLSI memory and a microprocessor.