Hewlett Packard HP-45

Serial Number 1349S02146: 1973, 49th week, Singapore
Accessories Power supply

Battery pack, can be equipped with regular AA batteries

HP-45 Quick Reference Guide

Manual: HP-45 Bedienungshandbuch (German), front page in bad condition, newly bound

Manual: HP-45 Owner's Handbook
Condition Silver lining a little scratched, has been manually repainted, unit has been opened (bent edges of rear label)
Repairs 27.6.2002 Fixed Bedienungsanleitung with a ring-binder. Cleaned inside (on/off switch) and out, especially keys. Cut open the battery pack so that now rechargeable or normal AA batteries can be inserted.
Has the built-in timer, see description below.
After letting the timer run for 2min it displayed "00.01 49  02" which is 1min 49sec - so indeed the timer is terribly inaccurate!
Acquired 19.6.2002
Inside HP-45
The picture shows the insides of the above 1349S02146 calculator.
The enumerated integrated circuits carry the following labels:
  1. 7343PEL, 1818-0078
  2. MOSTEK MK6105P, 1818-0057, ASSY IN MAL, 7343 H
  3. MOSTEK MK6106P, 1818-0082, ASSY IN MAL, 7343 H
  4. MOSTEK MK6036P, 1820-0993, ASSY IN MAL, 7341 L
  5. 7312KDL 1820-0848

Serial Number 1349S47236: 1973, 49th week, Singapore.
Accessories Pouch

Manual: HP-45 Bedienungshandbuch (German, 67 pages, dated March 1974)

Quick Reference: HP-45 Kurzanleitung (German, 25 pages, dated March 1974)

Leaflet: Zubehör für Taschenrechner Hewlett-Packard (List of Accessories, German)

4 sticky name tags

AC 220V power supply

Large gray protective plastic box.

Battery pack, dead
Condition Absolutely excellent! Only minor wearing of the silver lining near the power switch. The keys have a quite serious bouncing problem.
  • Has the built-in timer. But when pressing the decimal key to return to normal operation mode the display goes blank and the unit must be turned off and on to resume normal operation. 
  • When storing a time in one of the registers 1-9 and retrieving the number in normal operation mode strange things are displayed. Ie. a time stored after 6:37 sec is displayed as the non-normalized number 0.000000600 E 37 ! Multiplying this by 1 returns 6E30. This is different from the behaviour of the above unit!!
  • Letting the timer run for 2min displays 1:47 which is an even worse accuracy than the other HP-45 model.
Acquired 16.2.2004
HP codename, series Wizard, Classic
Type, Precision, Input Mode Scientific, 10 BCD digits, exponent ±99, Reverse Polish Notation
Programmable No
Memory No permanent memory. Registers 1-9.
Display 13 digit 7 segment red LED plus sign
Special features Earlier HP-45 models have code to implement a timer. This was never exposed as a user feature because the lack of a quartz crystal made the timer fairly inaccurate. Pressing RCL and then pressing CHS 7 8 all at the same time invokes the timer mode with the value of X as the starting time. Once in timer mode, the following commands are available:
  • CHS toggles it between running and stopped. 
  • SUM+  stops the timer.
  • CLx resets the timer to zero both in stopped and running mode.
  • EEX turnes on/off the 1/100th second display.
  • 1 - 9 stores the current time in that register when the timer was running or recalles the stored time when the timer was stopped. 
  • The decimal point key brings the calculator back to normal mode with the time still in the display. 
  • Enter also resumes normal mode but cleares the display.
It's possible to add a crystal to the HP-45. The timer software was later used in the HP-55.
Original Pricing, Production 1.5.1973 ($395) - 15.1.1976 ($195)
Batteries 3x AA pack. Calculator works with power supply and no battery pack installed
Dimensions Length 15.1cm, Width 8cm, Height 3.6cm
Links HP-45 Owner's Handbook, Nov 1974 (PDF)
HP-45 Applications Book, Dec 1974 (PDF)
HP-45 Bedienungs-Handbuch, October 1973 (PDF, German)
HP-45 Kurzanleitung (PDF, German)
Quick Reference (PDF)
Comparisn sheet with Corvus 500 (JPG)
Comment HP's third calculator.
Corvus tried to rival it with their Corvus 500 calculator. It was certainly cheaper and offered more functions (see also the Comarisn Seet)
The handbook tells the story about Henry Stafford who in his mind squared the number 365365365365365365 - something that reportedly even "today" (in 1974) no calculating machine can do. In 2004 this is of course quite different: An HP-49g+ in exact mode can easily perform this calculation and thereby prove that the result given in the German manual is wrong! But even an HP-45 is sufficient to see this immediately: Simply multiply 365*365=133225 and compare this to the number 133...255 given in the manual to see that the 2nd to last digit is wrong. This by the way is the only incorrect digit. And the English manual is correct in all digits.
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