Hewlett Packard HP-35s
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Hewlett Packard HP-35s
- Type: Programmable RPN/Algebraic Electronic Calculator
- Size: 3.25 x 6.25 inches / 8.5 x 16 cm
- Serial number: CNA 73502313
- Date of Manufacture: September 2007
Hewlett-Packard celebrates the 35th anniversary of the HP-35, their new-fangled electronic slide rule device, with a new back-to-the-future offering, the HP-35s.
The first thing you notice is the "retro" styling, the black faceplate, the keys overloaded with several functions and the double width ENTER key. (Especially the ENTER key. I'm cheered that HP is no longer ashamed of the ENTER key and no longer feels the need to hide the poor thing on the bottom row.) The functions shown on the keyboard are consistent with the HP-33s and my initial thought that the 35s was a restyling of the 33s. Well, if you've ever seen a 33s, that would be reason enough to upgrade. If you haven't seen the 33s, here are the two calculators side by side:
Some secondary functions are drawn on the key faces which drastically declutters the backplate. The "retro" styling brings back the gold and blue keys for secondary functions. Blue labels are reasonably visible in good light despite the lack of color contrast. Related functions are closer together. The XEQ and RTN functions are on the same key on the 35s. On the 33s they were nowhere near each other. Some additional decluttering was achieved by moving some functions to menus, for example the RPN/Algebraic selection has been moved off of a key and into the MODE menu.
The styling is great, but there are a number of improvements under the hood as well. Both calculators make 31K of memory available to the user; the 35s gives the user more access to this space by providing up to 800 indirect storage registers. Gone is the i-register the 33s used for indirection, but the 35s allows you to use two general-purpose registers, I and J, to access indirect registers. The 35s doesn't handle matrices directly as the HP-15C does, but the added memory access and two indirection registers should permit effective matrix programs.
Keystroke programming is similar to the 33s. There are 26 labels, A-Z. You can GTO and XEQ any label, or any line between labels. [XEQ] [ A ] [ENTER] executes subroutine A from the beginning. You can also XEQ A002 to start the routine two instructions in. While this is great when writing programs, it adds one keystroke to the execution. Neither calculator has programmable hot keys.
Complex number operations are greatly improved. The 33s required two stack levels for each complex pair, allowing you to have only two numbers on the stack. The 35s allocates three memory registers per stack level. Using two of these registers allows a complex number to be stored in each of the four stack levels. The trigonometric and transcendental functions work with complex numbers, but the square and square root keys do not. You can't take the square root of -1 directly. (Work around: [ 0 ] [ i ] [ 0 ] [ + ] [ 2 ] [ 1/x ] [ yx ]). Complex numbers can be entered in rectangular form (3 i 4) or polar (5 θ 53.13). Entries will be automatically converted to the selected display preference. There are no polar-rectangular conversion functions; to "convert" select the appropriate display choice.
Making use of the third memory register in each stack level, the 35s supports some basic operations on two- and three-dimensional vectors. You can add, subtract, multiply and divide by a scalar, absolute value and dot product. The manual gives a program listing for cross products.
The 35s includes HP's famous equation solver. You may store user-defined equations in memory and solve systems of linear equations in two and three dimensions. The last extension to the 33s's functionality is simple operations on binary integers. Binary, octal and hexadecimal are available. Arithmetic is two's-complement and the word size is fixed at 36 bits. (Clearly HP has been infiltrated by the PDP-10 crowd!)
The manual is complete. If you get this unit, keep it handy.
The unit is powered by two CR2032 cells. If you replace them one at a time, memory will be preserved.
If you own an HP-33s, grab it, place it under the back wheel of your car and drive over it. Now, since you're in the car anyway, drive to the store and get an HP-35s.
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