The Museum of HP Calculators

HP Forum Archive 14

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HP 9915A
Message #1 Posted by rhahm on 17 July 2004, 12:04 p.m.

I recently aquired an HP9915A computer/calculator which is the industrial version of the HP85.

Does anyone have the owner's manual for this.

If any one has the keyboard and would like to sell it or trade for it email me.

Also anyone has any series 80 software they want to trade email me.


Re: HP 9915A
Message #2 Posted by Vassilis Prevelakis on 17 July 2004, 3:42 p.m.,
in response to message #1 by rhahm

Tony Duell sent me the pinouts for the 9915A/B keyboard and control connectors.

The keyboard connector is:

        1 : Shield      14 : C0
        2 : R0          15 : C1
        3 : R1          16 : C2
        4 : R2          17 : C3
        5 : R3          18 : C4
        6 : R4          19 : C5
        7 : Ground      20 : C6
        8 : Ground      21 : C7
        9 : R5          22 : Shift/
        10 : R6         23 : Ctrl/
        11 : R7         24 : Capslock/
        12 : R8         25 : Speaker
        13 : R9

The keyboard matrix is the same as the 85, and is connected between the row (Rn) and column (Cn) lines The shift, control, and capslock keys are connected between the appropriate pin and ground. The speaker is an 8 ohm unit, connected between pin 25 and ground.

The Control connector, a DA15, has the following pinout :

        1 : LED0         9 : Run/
        2 : LED1        10 : Test
        3 : LED2        11 : Power OK
        4 : LED3        12 : Ground
        5 : LED4        13 : StartSw/
        6 : LED5        14 : TestSw/
        7 : LED6        15 : Shield
        8 : LED7

It basically carries the signals used on the front panel PCB. LEDn are the 8 user-definable LEDs. Run and Test are the signals for the 2 LEDs with those labels on the panel (note that one seems to be inverted, the other isn't!). The 2 switch signals correspond to the run and test switches on the panel -- the external switches go between those signals and ground.

You can turn on these LEDs with the SLITE(A,B) command (where A is a mask identifying the LEDs that should be controlled and B is the action, 1 for ON, -1 for OFF).

The 4 function keys on the left of the front panel are just the user definable keys on the HP85, and appear in the keyboard matrix as you'd expect.

The video connector is composite monochrome video at (US) TV scan rates. Just about any composite mono monitor will work.

98155A Keyboard Matrix
Message #3 Posted by Vassilis Prevelakis on 19 July 2004, 2:48 p.m.,
in response to message #2 by Vassilis Prevelakis

I got the following info from ages ago. There were one or two minnor mistakes in the table which I corrected.


98155A Keyboard Matrix

Everything in caps is as it appears on the keyboard. Names that are too long are abbreviated and shown in lower case. A list of the abbreviations and their meanings is also shown below.

    pin     21      20      19      18      17      16      15      14
    2       nu      kl      K1      K2      K3      K4      ua      da
    3       1       2       3       4       5       6       7       8
    4       Q       W       E       R       T       Y       U       I
    5       A       S       D       F       G       H       J       K
    6       sb      Z       X       C       V       B       N       M
    13      nu      nu      -l      rd      -CHAR   REP     ->      <-
    12      nu      RESET   bs      nu      =       -       0       9
    11      nu      nu      nu      sca     )       (       P       O
    10      nu      nu      nu      nu      el      '       ;       L
    9       nu      nu      nu      RUN     PAUSE   ?       >       <


  • nu = not used
  • da = down arrow (up and down arrow are used to recall previous commands and for editing)
  • ua = up arrow
  • rd = roll down (key to allow screen roll up/down)
  • kl = Key Label
  • el = End Line (this is what HP uses for carriage return/Enter)
  • sb = space bar
  • bs = Back Space
  • -l = -Line (erases the entire line)
  • sca = Scratch (erases all memory, just variables, etc depending on what argument you give it)

Notes: The K keys are programable function keys. K5 through K8 are K1 through K4 shifted. You can assign programs or functions to these keys and use the Control input lines to trigger the program or function. The -Char key erases one character at a time. the REP key toggles between the insert and replace modes.

There are a few more keys that don't fit into a matrix. Here's a list of them and the two pins that they connect to:

  • Both SHIFT keys are tied together in parallel and connct to pins 18 and 7.

  • There is a 8 Ohm .2Watt speaker inside. It connects to pins 25 and 7.

  • CNTL key connects to pins 23 and 7.

  • CAPS LOCK key connects to pins 24 and 7.

Re: HP 9915A
Message #4 Posted by Eric Smith on 18 July 2004, 3:41 a.m.,
in response to message #1 by rhahm

I need a keyboard too!

I wonder if it's a dumb keyboard - just a key matrix wired to the connector. Since the 9915A mainframe probably has to have the keyboard controller anyhow for the firmware to function, this wouldn't surprise me. And if so, it should be easy to wire one up.

Re: HP 9915A
Message #5 Posted by Vassilis Prevelakis on 18 July 2004, 1:06 p.m.,
in response to message #4 by Eric Smith

eric smith wrote:
> I wonder if it's a dumb keyboard

Didn't you read my previous posting? Its just a matrix of key switches. According to Tony's email the layout of the matrix is identical to that of the Series 80 keyboards. So you can make a 9915 kayboard by taking the keyboard of an HP-85 and connecting it to the keyboard connector of the 9915A with passive wires (i.e. no logic).


Re: HP 9915A
Message #6 Posted by Tony Duell on 19 July 2004, 2:26 p.m.,
in response to message #4 by Eric Smith

It is just a matrix of switches (well, with separate connections for shift, control and caps lock). The matrix seems to be the same as on the 85 (which is documented -- with 1 error -- in the service manual on the museum CD-ROMs).

The same keyboard controller as on the 85 is on the mainboard of the 9915. Quite a few of the 'chips' on teh vertically-mounted I/O card are actually diode arrays to protect the MOS inputs on this chip from external ESD. Vassilis has posted the pinout of the connector.

Incidentally, the same keyboard chip is used in the 86B (I have one in bits on my bench at the moment) and presumably in other 80-series machines. The keyboard matrix of the 86B is basically similar to the 85, in that the 'standard' keys (letters, digits, etc) are in the same places.

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