Hewlett-Packard HP-700LX

Datasheet legend
Ab/c: Fractions calculation
AC: Alternating current
BaseN: Number base calculations
Card: Magnetic card storage
Cmem: Continuous memory
Cond: Conditional execution
Const: Scientific constants
Cplx: Complex number arithmetic
DC: Direct current
Eqlib: Equation library
Exp: Exponential/logarithmic functions
Fin: Financial functions
Grph: Graphing capability
Hyp: Hyperbolic functions
Ind: Indirect addressing
Intg: Numerical integration
Jump: Unconditional jump (GOTO)
Lbl: Program labels
LCD: Liquid Crystal Display
LED: Light-Emitting Diode
Li-ion: Lithium-ion rechargeable battery
Lreg: Linear regression (2-variable statistics)
mA: Milliamperes of current
Mtrx: Matrix support
NiCd: Nickel-Cadmium rechargeable battery
NiMH: Nickel-metal-hydrite rechargeable battery
Prnt: Printer
RTC: Real-time clock
Sdev: Standard deviation (1-variable statistics)
Solv: Equation solver
Subr: Subroutine call capability
Symb: Symbolic computing
Tape: Magnetic tape storage
Trig: Trigonometric functions
Units: Unit conversions
VAC: Volts AC
VDC: Volts DC
Years of production:   Display type: Graphical display  
New price:   Display color: Black  
    Display technology: Liquid crystal display 
Size: 7"×7½"×2" Display size:  pixels
Weight: 16 oz    
    Entry method: Spreadsheet calculation 
Batteries: 2×"AA" alkaline + 1×"CR-2032" Lithium Advanced functions: Trig Exp Lreg Grph Solv Fin Cmem RTC Snd Mtrx BaseN 
External power: HP adapter   Memory functions: +/-/×/÷ 
I/O: Serial port, IR port, PCMCIA, cell phone     
    Programming model: Spreadsheet data 
Precision: 16 digits Program functions: Jump Cond Subr Lbl Ind  
Memories: 1(0) megabytes Program display: Formula display  
Program memory: 1 megabytes Program editing: Formula entry  
Chipset: Intel 80x86   Forensic result:  

hp700lx.jpg (59846 bytes)The HP-700LX is a special version of the HP-200LXhandheld computer, with an integrated NOKIA 2110i cellular telephone.

The machine I received from Singapore recently appears to have been well used. Worse yet, at first it wasn't behaving properly. Although it powered up, its display appeared corrupted, and invariably after a few seconds, it lost its mind: froze, went blank, started beeping, or exhibited other forms of erratic behavior.

It is easy to disassemble the lower half of the HP-700LX, which provides access to the main CPU board. Unfortunately, I found no obvious signs of any problems there. One possibility was that it could have been a clock-upgraded machine, but I eventually had to discard that theory as well.

So I decided to disassemble the upper portion. This is much harder, as you must remove the plastic bezel around the display, you must "pop" the plastic hinge cover, and after removing four screws, you must also "pop" the two halves of the display portion apart. I managed to do all this without damaging the plastic or breaking anything. Once I had access to the inside, I was able to thoroughly clean the display, free a stuck component that did not permit the cellular phone to be fully latched, and I also cleaned and reseated pressure contacts that connect the display to a ribbon cable. After reassembly, the display corruption disappeared, and at first, the machine actually seemed to operate normally.

Eventually, however, it froze again. This is when I realized that a mechanical impact (the technical term is a "whack") had a visible effect. So the problem is a bad contact after all! I once again disassembled the machine, reseated ribbon contacts, and looked for other signs of faulty mechanical contacts or bad solder joints. I haven't found anything. Right now, the machine works, but I fear that it may again stop working, either in response to impact, or entirely on its own if the faulty contact misbehaves again.

nk2110i.jpg (21139 bytes)The integrated cell phone is an early data-capable GSM model from Nokia, the 2110i. Since it is a 900MHz single-band model, I cannot test it on the Rogers AT&T's 1900 MHz North American GSM network. It is also misbehaving when I insert my SIM card. Whether it is because the phone is faulty, SIM-locked, or some other reason, I don't know.

The cellular phone is inserted at the top of the machine. When it is pushed into position, it is latched securely. Since the keypad and display face upward, the phone+PDA combo can in fact be used as a somewhat bulky telephone without having to unlatch the phone first.

When you open the machine with the phone attached, the top half is very heavy, so the machine would tip over, were it not for an extra stub that is attached to the battery compartment door and can be folded out to provide extra stability. Whacky.

Accompanying the cellular phone is a Nokia DTP-2 cellular data card. This card is cleverly hidden inside the HP-700LX, connected to a second PCMCIA slot that is accessible only internally.

The standard suite of ROM-based drivers and applications found in the HP-200LX has been expanded and modified to work with the cellular phone. A good example is the SMS application that lets you retrieve, view, and send SMS messages using the wireless phone.