here is a ti 59 from 1977. this was the most advanced model
at the time with 960 program steps (max) and 100 memories (max). program
steps and memories are interchangeable. it did not have continuous memory,
but was equipped with a magnetic card reader/writer similar to that of the
like the ti58, it could accommodate a rom module
that fitted into the back of the machine. the module contained a library
of programs and came with a wallet of cards describing the functions of
the A-E keys for each program when selected. use of the rom programs did
not occupy program memory and could even be called from user programs as
build quality was adequate, better than the ti57,
but not in the same league as hp. the buttons click and they do not last
the test of time. a common fault of these machines is for buttons to
bounce or become squelshy. i could forgive the ti57
but not on the more expensive 58 and 59.
the unit is powered by a rechargeable battery pack (bp-1a) and comes
with a mains adapter/charger. the battery pack contains 3 AA ni-cad cells
and is sealed. this is a pity because it would have been handy if the
cells could be popped out and replaced by new ones.
the machine operated a 10 digit result with 3 internal digits making a
total of 13 digit precision very accurate for the time (and indeed today).