123 was fun to use what little I did with it.
Up until 5 or 6 years ago, 123 was still around at works via some emulation.
The original 1-2-3 was lightning fast because it was written in assembler, and stored the entire sheet in active RAM memory.
That reminds me of a story. The State of Connecticut had a bureau that stored a large, important database in 1-2-3. Unlike dBase, Paradox or aRev it kept the whole thijng in active memory, so as the IBM-AT 80286 ran out of RAM memory, more RAM was added, from 512K to 1,024K, to 4 meg, and finally to 16MB. When they hit the hardware wall at 16MB, they lost the whole database. True story!