Spice series calculators, which include the LED HP-31E, HP-32E, HP-33E/C, and HP-34C scientific calculators, can be tested by simply pressing STO, then pressing ENTER. After a couple of seconds, all segments in the display will light to indicate the calculator successfully completed its internal self-test.

This STO then ENTER test probably also works with the HP-37E and HP-38E/C business calculators, but this has not been verified by this author.

Voyager series calculators, which include the HP-10C, HP-11C, HP-12C, HP-15C, and HP-16C have two separate test functions, the internal/display self-test, and a keyboard test.

To perform the internal/display self-test, with the calculator off, press and hold the multiply key, press and release the ON key, then release the multiply key. The calculator will flash "running" in the display for twenty-five seconds while the internal test is performed. The test ends with all segments and annunciators in the display turned on. (The internal self-test can be performed continuiously by pressing the ON and plus keys simultaneously. Pressing any key will end the test at the end of the current twenty-five second cycle.)

To perform the keyboard test, with the calculator off, press and hold the divide key,press and release the ON key, then release the divide key. Then, in order press each key from left to right on each row, from the top row to the bottom row. Press the ENTER key in order for both the third and fourth row. Different segments in the display will be turned on as each test key is pressed. If all keys are pressed in the proper order and are all working correctly, the model number of the calculator will be displayed. If a key is pressed out of order, or there is a problem with the keyboard, "Error 9" will be displayed.

The HP-18C built in internal, display, and keyboard test functions.

A continuous internal/display test is performed by simultaneously pressing the ON key and the fifth key on the top row (labeled "E" in the illustration below). Various internal and display tests will be performed until interrupted by simultaneously pressing the third key on the top row (labeled "C" in the illustration below) and the ON key. After the test is exited, "MACHINE RESET" will be displayed.

The more thorough internal/display/keyboard test is performed by pressing the ON key and the fourth key on the top row (labeled "D" in the illustration below). Press any key to step through the various display and internal tests until "KEYBOARD TEST" is displayed. Starting with the left keyboard, in order press each key from left to right on each row, from the top row to the bottom row. Then proceed to press each key on the right keyboard in order from left to right and top to bottom. If the test is successful, "OK-18C-E" will be displayed. If a key is pressed out of order or there is a keyboard problem, and error message will be displayed. This test can be interupted at any time as described above.

These same tests can probably be performed on HP's other clamshell business calculators, but that has not been verified by this author.

The HP-28C and HP-28S have built in internal, display, and keyboard test functions.

A continuous internal/display test is performed by simultaneously pressing the ON key and the left-arrow key (labeled "E" in the illustration at the right). Various internal and display tests will be performed until interrupted by simultaneously pressing the up-arrow key (labeled "C" in the illustration at the right) and the ON key.

The more thorough internal/display/keyboard test is performed by pressing the ON key and the down-arrow key (labeled "D" in the illustration at the right). Press any key to step through the various display and internal tests until "KEYBOARD TEST" is displayed. Starting with the left keyboard, in order press each key from left to right on each row, from the top row to the bottom row. Then proceed to press each key on the right keyboard in order from left to right and top to bottom. If the test is successful, "OK" followed by the model number will be displayed. If a key is pressed out of order or there is a keyboard problem, and error message will be displayed. This test can be interupted at any time as described above.

The Pioneer series calculators, which include the HP-10B, HP-14B, HP-17B, HP-17BII, HP-20S, HP-21S, HP-22S, HP-27S HP-32S, HP-32SII, and HP-42S all have built-in internal, display and keyboard test functions. The keystrokes to access the self-test functions of each calculator are the same for all pioneer models (ignoring the keyboard nomenclature for each specific model).

A continuous internal/display test is performed by simultaneously pressing the ON key (labeled "C", "CLR" or "EXIT" on various models) and the key labeled "E" (the fifth key on the top row) in the illustration at the right. Various internal and display tests will be performed until interrupted by simultaneously pressing the key labeled "C" (the third key on the top row) in the illustration at the right and the ON key.

The more thorough internal/display/keyboard test is performed by pressing the ON key and the key labeled "D" (the fourth key on the top row) in the illustration at the right. Press any key to step through the various display and internal tests until after the copyright notice is displayed. "KBD" on calculators with alpha-numeric display capability or "01" on calculators with only a numeric display will be displayed to indicate the start of the keyboard test. In order press each key from left to right on each row, from the top row to the bottom row. The calculator will indicate "OK" or "good" when the keyboard test is successfully completed. If a key is pressed out of order or there is a keyboard problem, and error message will be displayed. This test can be interupted at any time as described above.

WARNING: Invoking the tests described below may result in the clearing of data memory, program memory, and mode settings. Also seen the annunciator note below.

The HP-33S has built-in internal,display and keyboard test functions. The keystrokes to access the self-test functions are similar to that for the pioneer models.

A continuous internal/display test is performed by simultaneously pressing the C (Clear/ON) key and the ¹/x key. Various internal and display tests will be performed until interrupted by pressing any key - the current test cycle, lasting up to a couple of seconds, will finish first. This test may be immediately interrupted by simultaneously pressing the LN key and the C key.

The more thorough internal/display/keyboard test is performed by simultaneously pressing the C key and the y^x key. Press any key eight times to step through the various display test patterns. A copyright notice ("© HP DEV CO. L. P.") will be momentarily displayed, then "KBD 01" will be displayed to indicate the start of the keyboard test. In order, press each key from left to right on each row, from the top row (starting with the e^x key) to the bottom row. Then continue by pressing the keys in the silver chevron below the display in the following order: ENG, cursor-up, MODES, cursor-left, cursor-right, SOLVE, cursor-down, and DISPLAY. The calculator will display "33S-OK" when the keyboard test is successfully completed. If a key is pressed out of order or there is a keyboard problem, an error message will be displayed. The self-test is exited by simultaneously pressing the LN and ON keys.

Note: Due to an apparent ROM bug, the annunciators indicating the various modes and states of the calculator may not be properly displayed after completing the self-test. You must manually set these modes to place the annunciators in their proper state.

WARNING: Invoking the tests described below may result in the clearing of data memory, program memory, and mode settings.

The HP-335 has built-in internal,display and keyboard test functions. The keystrokes to access the self-test functions are similar to that for the pioneer models.

A continuous internal/display test is performed by simultaneously pressing the C (Clear/ON) key and the MODE key. Various internal and display tests will be performed until interrupted by pressing any key - the current test cycle, lasting up to a couple of seconds, will finish first. This test may be immediately interrupted by simultaneously pressing the GTO key and the C key.

The more thorough internal/display/keyboard test is performed by simultaneously pressing the C key and the XEQ key. Press any key eight times to step through the various display test patterns. A copyright notice ("© 2007 HP DEV CO. L. P.") will be momentarily displayed, then "KBD 01" will be displayed to indicate the start of the keyboard test. Starting with the R/S key, press the first four keys on the top row from left to right. Then press the up-cursor key, left-cursor key, and right-cursor key. Then, starting with RCL key, press the first four keys on the second row. Then press the down-cursor key. Then, starting with the SIN key on the third row, continuing pressing each key from left to right on each row, and continue to the bottom row. After the last key, the + (plus) key is pressed, the calculator will display "35S-OK" to indicate the keyboard test has successfully completed. If a key is pressed out of order or there is a keyboard problem, an error message will be displayed.

The self-test is exited by simultaneously pressing the GTO and C keys.

The HP-71B has an internal ROM self test which can be invoked by simultaneously pressing ON and the divide key ("/"). Then press 2. Finally press END LINE to start the test.

WARNING: Invoking the test described below may result in the clearing of data memory and mode settings.

The HP-30S has built in display and keyboard tests. The test menu is accessed by pressing 2nd, then Reset (the reset menu is displayed), then simultaneously pressing 2nd, +/- and DEL. The test menu is displayed: "TEST:1)D2)K".

Display test. Press 1 to access the display test. Press ENTER repeatedly to cycle through the three different test patterns. Press DRG to abort the display test and return to the test menu.

Keyboard test. Press 2 to access the keyboard test. Forty-eight columns of pixels on the top line are displayed. Unlike other HP keyboard tests, the keys do not need to be pressed in any particular order. As each key is pressed, a column of pixels is turned off. The keyboard test is complete when all pixel columns are turned off. Then press ENTER to return to the test menu.

From the test menu, press ENTER" to return to the reset menu.

WARNING: Invoking the test described below may result in the clearing of data memory and mode settings.

The HP-10BII built in test consists of a combined display and keyboard test. The display test consists of eight distinct test patterns (amortization annunciators, cash flow annunciators, error annunciators, mode and status annunciators, vertical segments for each digit, horizontal segments for each digit, decimal points, and decenders for the commas). The keyboard test, which tests each row and column scan line, is accomplished as eight keys are pressed in the order enumerated below. There is no comprehensive keyboard test as found on many other HP calculators.

The display/keyboard test is invoked by simultaneously pressing the ON and PMT keys. Then an unusual sequence of eight additional keys is pressed, exactly in the order enumerated below, to step through the display/keyboard test. Finally, ON is pressed to exit the test mode.

With the calculator on, simultaneously press the ON key and the PMT key to invoke the display test and display the first test pattern, the amortization annunciators. Then, press the following eight keys in order:
[N] to display the cash flow annunciators.
[MU] to display the error annunciators.
[CFj] to display the mode and status annunciators.
[RM] to display the vertical segments for each digit.
[÷] to display the horizontal segments for each digit.
[6] to display the decimal points.
[2] to display the decenders for the commas.
[0] to start the calculator automatically cycling through the eight test patterns.
If any key is pressed out of order, "FAIL" will be momentarily displayed before the calculator exits the display test.

Press the ON key to exit the display test. The message "GOOd" is momentarily displayed.

WARNING: Invoking the test described below may result in the clearing of data memory, program memory, and mode settings.

The HP-39G has built-in internal, display, and keyboard test functions. These functions are accessed by pressing and holding the ON key then pressing one of the keys on the top row of the keyboard, as is done on many other late model HP calculators.

A continuous internal/display test is performed by simultaneously pressing the ON key and the fifth key (labeled "E" in the illustration to the right) on the top row. This test will cycle through ERAM, CPU, RAM, and display tests, then briefly display "HP 39/40 OK" before starting again. This cycling test is cancelled by simultaneously pressing the ON key and the third key (labeled "C" in the illustration to the right) on the top row.

Individual tests can be performed by simultaneously pressing the ON key and the fourth key (labeled "D" in the illustration to the right) on the top row. A menu listing seven test options will be displayed. These test options are Hard, Cpu, Kbd1, Kbd2, FullRAM, RS232, and IR. Press the appropriate number for the test. This test mode can be exited either by pressing ON, or simultaneously pressing ON and the third key (labeled "C" in the illustration to the right) on the top row.

• 1: Hard. This test displays the messages "Write to ERAM OK" and "Calculator is HP39G."
• 2: Cpu. This is the CPU test, and displays three lines of results.
• 3: Kbd1. This test requires you to press each key from left to right, from the top row to the bottom row. The Up-Cursor key is the right most key of the second row. The Left-Cursor, Down-Cursor, and Right-Cursor keys are the last three keys of the third row. The calculator beeps as each key is pressed. If a key is pressed out of order or bounces, a different beep is heard and a four-digit hexadecimal number will be displayed, and the test will expect the remaining 51 key depressions before displaying a failure message. Upon successful completion of the test, the message "Kbd1 OK" is momentarily displayed before the test menu is redisplayed.
• 4: Kbd2. This test required you to press only some of the keys on the keyboard. (The HP-48GX Kbd2 test appears to test keyboard scan lines, so presumably this test does the same thing.) The following keys must be pressed in the following order to successfully finish this test: the six keys on the top row from left to right, SYMB, PLOT, NUM, HOME, APLET, VIEWS, Cursor-Left, and finally the Comma key. If a key is pressed out of order or bounces, a different beep and a four-digit hexadecimal number will be displayed. The message "Kbd2 OK" is momentarily displayed upon successful completion of the test.
• 5: FullRAM. This test tests all 256K of RAM in the calculator. "OK" is displayed as the test of each 128K bank is completed.
• 6: RS232. Tests the RS232 I/O port.
• 7: IR. Tests the IR I/O port.
• ON: Reboot. Exits the self test function and resets the calculator.

A quick test can be performed by simultaneously pressing ON and the sixth key (labeled "F" in the illustration to the right) on the top row. This test cycles through the ERAM, CPU, RAM, display, Kbd2, RS232 and IR tests. This test can be exited by pressing ON and the third key (labeled "C" in the illustration to the right) on the top row simultaneously.

WARNING: Invoking the test described below may result in the clearing of data memory, program memory, and mode settings.

The HP-48 series calculators have built-in internal, display, and keyboard test functions. These functions are accessed by pressing and holding the ON key then pressing one of the keys on the top row of the keyboard.

A continuous internal/display test is performed by simultaneously pressing the ON key and the E key (the fifth key on the top row). This test will cycle through CPU, display, IROM, and IRAM tests. "OK-48" is briefly displayed before starting over. This cycling test is cancelled by simultaneously pressing the ON key and the C key (the third key on the top row).

Individual tests can be performed by simultaneously pressing the ON key and the D key (the fourth key on the top row). No menu is displayed, however a vertical line is displayed down the center of the display. Most of the keys in the top five rows of the keyboard have a unique test assigned to them, however only those tests associated with the top row of keys will be discussed. Simultaneously press ON and C (the third key on the top row) to exit the individual test mode.

• A: SPD. This appears to be a CPU test.
• B: Display. This display test generates a series of test patterns. A key must be pressed to sequence through the seven test patterns.
• C: IROM. This test tests the internal ROM of the calculator. If the test completes successfully, "IROM OK" is displayed.
• D: IRAM. The internal RAM of the calculator is tested. If the test completes successfully, "IRAM OK" is displayed.
• E: KBD1. This test requires you to press each key from left to right, from the top row to the bottom row. The calculator beeps as each key is pressed. If a key is pressed out or order, a different beep is heard and a five-digit hexadecimal number will be displayed. Upon successful completion of the test, the message "KBD1 OK" is displayed.
• F: KBD2. This test appears to test the keyboard scan lines, and requires only a few keys to be pressed. The following keys, outlined in yellow in the illustration at the right, must be pressed in the following order to successfully complete this test: B, CST, Cursor-Left, y^x, Backspace, Alpha, 4, 2, SPC. "KBD2 OK" displayed upon successful completion of the test.

WARNING: Invoking the test described below may result in the clearing of data memory, program memory, and mode settings.

The HP-50G, software wise, represents the continuing evolution of the HP48G family. The HP50G has built-in internal, display, and keyboard test functions. These functions are accessed by pressing and holding the ON key then pressing one of the keys on the top row of the keyboard.

A continuous internal/display test is performed by simultaneously pressing the ON key and the F5 key (the fifth key on the top row). This test will cycle through tests for the display, ROM, RAM, flash memory, RS-232 loopback, IRDA loopback, SD flash card (if present), and the beeper. The pass/fail status is briefly displayed for each test as it completes. This cycling test is cancelled by simultaneously pressing the ON key and the F3 key (the third key on the top row).

Individual tests can be performed by simultaneously pressing the ON key and the F4 key (the fourth key on the top row). Software build information is briefly displayed, then a test menu is displayed.

   1.LCD      2.KEY
   3.FLASH    4.SRAM
   5.USB      6.RS232
   7.BUZZER   8.IRDA
   9.CARD     A.AUTOTEST

Simultaneously press ON and F3 (the third key on the top row) to exit test mode.

• 1.LCD. This display test generates a series of test patterns, pauses at a contrast test (press + or - to adjust the contrast, and ENTER to continue), turns off the display momentarily, and waits for ENTER to be presssed to return to the main test menu.
• 2.KEY. This test requires you to press each key. Unlike prior HP calculators, this test does not require the keys to be pressed in any particular order. A grid, with small squares is displayed. As each key is pressed, the square associated with that key is cleared. Once all the keys have been pressed, the calculator automatically returns to the main test menu.
• 3.FLASH. This test option displays a submenu with two options: 1-QUICK FLASH TEST, and 2-FULL FLASH TEST.
• 4.SRAM. This test is performed in less than a second, and displays "SRAM TEST OK" when completed. ENTER must be pressed to return to the main test menu.
• 5.USB. This test asks for a USB cable to be plugged into the calculator. Press ENTER to return to the main test menu.
• 6.RS232. This test performs an internal loopback test, and displays "RS232 TEST OK." Press ENTER to return to the main test menu.
• 7.BUZZER This test option displays a submenu with three options:

     1-ALARM
     2-KEYTONE (120MS)
     3-KEYTONE (180MS)
  

  Each buzzer test allows the frequency to be adjusted. ENTER must be pressed to return to the buzzer test submenu. From the buzzer test submenu, ENTER must be pressed to return to the main test menu.
• 8.IRDA. This test performs an internal loopback test, and displays "IRDA TEST OK." Press ENTER to return to the main test menu.
• 9.CARD. This test requires an SD memory card. If no memory card is present, the message "PLEASE INSERT CARD" will be displayed if you try to execute this test. When a memory card is present, the following submenu is displayed:

     1.TEST
     2.FORMAT
  

  When the FORMAT option is selected, the following submenu will be displayed:

     1.START FORMATTING
  

  (If the memory card is write protected, the message "WRITE PROTECTED" and "FORMAT FAILED" will be displayed.) When the memory card is formatted, it will tell you how it is being formatted (e.g. "FAT32") and the size of memory card. When finished, "FORMAT FINISH" is displayed. At the end of each test or action, press ENTER to return to the previous menu or submenu.
• A.AUTOTEST. This test option (intiated by pressing F1) initiates the continuous/internal test described above. It is exited by simultaneously pressing the ON key and the F3 key (the third key on the top row).

WARNING: Invoking the test described below may result in the clearing of data memory, program memory, and mode settings.

The HP-38G has self test functions which are very similar to the HP-48 series (discussed above). Because of the similarities to the HP-48 series, only the differences will be discussed.

The continuous internal/display test briefly displays "OK-38" instead of "OK-48."

The KBD2 test requires the following keys to be pressed in the following order to successfully complete the test: B (second key on top row), NUM, Cursor-Left, the X,T,Ø key, X^y, A...Z, 4, 2, comma. These keys are in the same position and order as the yellow outlined keys shown in the HP-48G illustration above.

WARNING: Invoking the test described below may result in the clearing of data memory, program memory, and mode settings.

The HP-9G has built in display and keyboard tests. The test menu is accessed by pressing 2nd, then RESET (the reset menu is displayed), then simultaneously pressing the 2nd key, the (-) (change sign) key, and the ALPHA key. Three self test menu options are displayed.

   TEST:
   1D 2K
   3LOOP

Display test. Press 1 to access the display test. Press ENTER repeatedly to cycle through the three different test patterns. Press DRG to abort the display test and return to the test menu.

Keyboard test. Press 2 to access the keyboard test. Forty-eight dashes are displayed in a pattern that looks similar to the keyboard layout of this calculator's Kinpo SG1 cousin. Unlike many other keyboard tests, the keys do not need to be pressed in any particular order. As each key is pressed, a dash is turned off. The keyboard test is complete when all dashes are turned off. Then press ENTER to return to the test menu.

Looping display contrast test. Press 3 to access the display contrast test. The calculator automatically cycles through the display contrast settings with all pixels energized until the test is interrupted by pressing DRG. After interrupting this test, the test menu is redisplayed.

From the test menu, press "ENTER" to return to the reset menu.

(Based on several factors, I believe this calculator is manufactured by Kinpo Electronics, Inc., and is functionally identical to the Citizen/Kinpo SG1.)