HP 35s Scientific Calculator - Manual (Page 350)

F-4 Messages
   SOLVE (include EQN and PGM mode)cannot find the
root of the equation using the current initial guesses (see
page ). These conditions include: bad guess, solution
not found, point of interest, left unequal to right. A
SOLVE operation executed in a program does not
produce this error; the same condition causes it instead
to skip the next program line (the line following the
instruction  variable).
 Warning (displayed momentarily); the magnitude of a
result is too large for the calculator to handle. The
calculator returns ±9.99999999999E499 in the current
display format. (See "Range of Numbers and Overflow"
on page .) This condition sets flag 6. If flag 5 is set,
overflow has the added effect of halting a running
program and leaving the message in the display until
you press a key.
  Indicates the "top" of program memory. The memory
scheme is circular, so   is also the "line" after
the last line in program memory.
  The calculator is running an equation or program (other
than a SOLVE or ∫FN routine).
  Attempted to execute  variable or ∫  d variable
without a selected program label. This can happen the
first time that you use SOLVE or ∫
FN after the message
 , or it can happen if the current label
no longer exists.
  A running program attempted to select a program label
(label) while a SOLVE operation was running.
 A running program attempted to solve a program while
a SOLVE operation was running.
 ∫ 
A running program attempted to integrate a program
while a SOLVE operation was running.
 The calculator is solving an equation or program for its
root. This might take a while.
 Attempted to calculate the square root of a negative
number.