Serial number CNA 44206378, China, Plant "A", 2004
Accessories Pouch
Manual: "hp 33s wissenschaftlicher Taschenrechner Benutzeranleitung" (German, 2nd edition, Nov 2004)
Condition Bought new
Repairs, Comments
Acquired 22.2.2007 from Böttcher Datentechnik (www.taschenrechner.de)
HP codename, series Unknown
Type, Precision, Input mode Scientific, 12 BCD digits, exponent ±499, Algebraic or Reverse Polish Notation
Programmable Yes. Keystrokes, labels A-Z.
Performance Index 44
Memory 31277 bytes available by default. According to the manual the memory is shared by programs, formulas and variables.
26 number storage registers (A-Z), index register (i).
Interestingly, the free memory indication does not change when numbers are stored. So it seems the available bytes are available to programs and equations alone.
Assuming 32 kB of RAM 1491 bytes are used for number storage and internal data. There are 26 direct number registers (A-Z), the index register, LastX, 4 stack registers and 6 statistics registers, in total 38 registers. Assuming 8 bytes per number this adds up to 304 bytes. So approximately 1 kB is used by the calculator internally.
Display LCD with 2 rows and 14 digits each, 5x7 pixel per digit, annunciators
Special features RPN and algebraic entry mode, equations, hex, binary and octal mode, equation solver, integration, statistics, complex functions (but not a complex stack), fractions, unit conversions, many physical constants, program and formula checksums (used to verify transcriptions from printed listings).
Original Pricing, Production 61.95 Euro in 2007
Batteries 2x large button sized cells
Dimensions Length 15.8 cm, Width 8.3 cm, Height 1.6 cm
Links Manual: HP-33S Scientific Calculator User's Guide (PDF, English, 387 pages, 3rd edition, Nov 2004)
Manual: HP-33S Wissenschaftlicher Taschenrechner Benutzeranleitung (PDF, German, 408 pages, 2nd edition, Nov 2004)
HP-33s info on Finseth.com.
The Cosine bug.
Comments In the equation (EQN) and memory (MEM) menu it is possible to display the length of a program or an equation.
The "V" shaped keyboard together with the tilted labels and a wealth of commands make it very hard to find the right keys. In general, the design of this calculator doesn't look very appealing to me.

The Cosine Bug

Various sources on the internet report the "cosine bug". This bug is not present in the HP-33S' anchestors HP-32S or HP-32SII. And none of the other more recent units HP-6S/Solar, HP-30S or HP-50g are affected. So it must have been introduced with the HP-33s. This bug actually also affects the sine calulcation.

For one thing the identity sin(x) = cos(90 - x) is observed.
But for "somewhat small" arguments the iteration seems to be aborted too early. The critical point is between 5.7E-8 (correct) and 5.8E-8 (incorrect).
In Radians this corresponds to around 1E-9.
cos(90 - x)
1E-1 1.74532836590E-3
correct 1.74532836589 83E-3
1E-2 1.74532924306E-4 1.74532924306E-4
correct 1.74532924313 34E-4
1E-3 1.74532925091E-5 1.74532925091E-5
correct 1.74532925190 57E-5
1E-4 1.74532925000E-6 1.74532925000E-6
correct 1.74532925199 34E-6
1E-5 1.74532920000E-7 1.74532920000E-7
correct 1.74532925199 43E-7
1E-6 1.74532900000E-8 1.74532900000E-8
correct 1.74532925199 43E-8
1E-7 1.74532000000E-9 1.74532000000E-9
correct 1.74532925199 43E-9
1E-8 1.74532925199E-10 1.74532925199E-10
correct 1.74532925199 43E-10
1E-9 1.74532925199E-11 1.74532925199E-11
correct 1.74532925199 43E-11

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