The Blue/Black Whale is a modified Keyboard Component used by Mattel Electronics as development/debug systems when the standard dev hardware became scarce due to hiring so many engineers. The RAM of the Blue Whale was mapped to Intellivision console ROM.
Joe Zbiciak released a reverse engineering document in 2018 with how it was probably used.
Source Links:
web.archive.org/web/20221204051119/history.blueskyrangers.com/hardware/keyboardcomponent.html
media0101.intvprime.com/ba4ef/intellivision-echo/Hardware-Components/Keyboard-Component/Keyboard-Component-Black-Whale-Reverse-Engineering-Report-20180423a.pdf
media0101.intvprime.com/ba4ef/intellivision-echo/Hardware-Components/Keyboard-Component/Keyboard-Component-Black-Whale-Reverse-Engineering-Report-20180423b.pdf