Connecting a modem to your HP48 or HP49G calculator
by E.Carta
Version 3.00
Warning: This is *NOT* a Hewlett-Packard official page. I assume no responsibility about any damage you could get by following these schematics.
These pages explain how connecting any standard-modem to your HP48 or HP49 calculator.
Following instructions below, you'll be able to join BBS services, to chat and to upload or download files, both on remote PCs and even on a remote HP calculator !
You'll learn to build the connection cable and to get all the FREE required software .
You need the computer only the first time, to transfer terminal programs to your HP calculator. Then, you won't need other devices than your HP, the cable and the modem.
Notice: you won't be able to send/receive fax, neither to access Internet directly.
LCD SCREEN +--------------------'--------+ | +-----------------------+ | | | .... OO | | \ | 1234 (IR-LEDS)| / \_|_______________________|_/
PINOUT NUMBERING:
HP48-4pin-M HP48-4pin-F
[ 1 2 3 4 ] [ 4 3 2 1 ]
PINOUT DESCRIPTION:
1. SHIELD
2. TX (TRANSMITTED = CALCULATOR OUTPUT)
3. RX (RECEIVED = CALCULATOR INPUT)
4. GND
LCD SCREEN /|-----------------------------|\ | +---^-----------------+ | |____| ..... <pin 1 to 5 |____| | | ..... <pin 6 to 10 | | | \---------------------/ | \-------------------------------/
PINOUT NUMBERING:
HP49G-10pin-M HP49G-10pin-F
+-------/-\-------+ +-------/-\-------+
| 1 2 3 4 5 | | 5 4 3 2 1 |
| 6 7 8 9 10 | | 10 9 8 7 6 |
\-----------------/ \-----------------/
PINOUT DESCRIPTION: 6. SHIELD 7. TX (TRANSMITTED = CALCULATOR OUTPUT) 8. RX (RECEIVED = CALCULATOR INPUT) 9. GND
DB9-M DB9-F
------------------- -------------------
\ 1 2 3 4 5 / \ 5 4 3 2 1 /
\ 6 7 8 9 / \ 9 8 7 6 /
--------------- ---------------
PINOUT DESCRIPTION:
2. TX (MODEM INPUT = DATA FROM CALCULATOR)
3. RX (MODEM OUTPUT = DATA TO CALCULATOR)
4. DTR
5. GND
6. DSR
7. RTS
DB25-M DB25-F
--------------------------- ---------------------------
\ 1 2 3 [..] 11 12 13 / \ 13 12 11 [..] 3 2 1 /
\ 14 15 [..] 23 24 25 / \ 25 24 23 [..] 15 14 /
----------------------- -----------------------
PINOUT DESCRIPTION:
2. RX (MODEM OUTPUT = DATA TO CALCULATOR)
3. TX (MODEM INPUT = DATA FROM CALCULATOR)
4. RTS
6. DSR
7. GND
20. DTR
The cable you need should connect the modem and the HP calculator directly together. No PC is needed.
The HP calculators don't support RTS and DTR pins, required by most of the modems. So, you have to connect them to the DSR pin, whose signal is originated by the modem itself, at the end of the modem cable. Simply short pins 4, 6, 20 (on modem DB25-M connector) or pins 4, 6, 7 (if your modem uses a DB9-M).
A cable like this is not available, so you have to build it by yourself.
You have two ways to do it:
To know the pinout numbering used by me, please refer to the previous section.
3.1. Project #1: HP48 - Building the whole cable.
What you need: a DB25-M connector (or DB9-M if your modem uses it), some wires and a 4pin-F connector to plug into the HP48 port. Note that in the calculator you only need to connect three pins (since SHIELD is not mandatory); so you can get it by recycling the 3 (or 4)-pin female connectors used into old computer mainboards (for example: CD-ROM cable, HDD power-connector for portable computers, etc.).
Ask to a computer shop or, better, to a surplus-dealer in order to find a computer connector that fits your HP48 port.
Building the cable: Solder the 4-pin-F connector to the DB25-M (or to the DB9-M if your modem uses it).
Schematic:
HP48-4-F DB25-M DB9-M
SHIELD (1)-+-------------(SHIELD)
+--------------------------------(SHIELD)
TX 2-----+---------->2
+----------------------------->3
RX 3<-+--------------3
+<--------------------------------2
GND 4-----+-----------7
+------------------------------5
4,6,20 4,6,7 <--SHUNTED
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3.2. Project #2: HP49 - Building the whole cable.
What you need: a DB25-M connector (or DB9-M if your modem uses it), some wires and a 10pin-F connector to plug into the HP49G port. Note that in the calculator you only need to connect three pins (since SHIELD is not mandatory), all in the bottom-row (pin 7 to 9); so you can get it by recycling the 3 (or 4)-pin female connector used into old computer mainboards (for example: HDD-led, turbo-led, keylock-switch, etc.), or get it from some broken hardware (for example, an old mouse).
Ask to a computer shop or, better, to a surplus-dealer in order to find a computer connector that fits the pins (6),7,8 and 9 in your HP49G.
Building the cable: Solder the 3-pin-F connector to the DB25-M (or to the DB9-M if your modem uses it).
Schematic:
HP49-10-F DB25-M DB9-M
SHIELD (6)-+-------------(SHIELD)
+--------------------------------(SHIELD)
TX 7-----+---------->2
+----------------------------->3
RX 8<-+--------------3
+<--------------------------------2
GND 9-----+-----------7
+------------------------------5
4,6,20 4,6,7 <--SHUNTED
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3.3. Project #3: HP48 and HP49 - Building the adapter for cable F1897-66000.
What you need: some wires, a DB9-M and DB25-M connector (or two DB9-M connectors if your modem uses it) and the HP serial PC-Link cable. In this section I'm referring to newer models of cable (like F1897, F1207B or 8120-6736), that can be used on both HP48 and HP49G. For older cables (like F1015-80002) see section 3.4 or 3.5. The HP38 has the same pinout as the HP49G, so you can use also a HP38 PC-Link.
NEVER (**NEVER**) plug this cable directly into your DB9 modem. You could damage it!
To use this cable you need to build a DB9-DB25 adapter (or DB9-DB9 if your modem uses a DB9 connector).
Using the adapter.
+-----------------+ +-----------+ +---------+ | HP CALCULATOR |<-----------------><--| ADAPTER |-->| MODEM | +-----------------+ PC-LINK +-----------+ +---------+
Schematic of the adapter:
(TO PC-LINK) (TO MODEM) (TO MODEM)
DB9-M DB25-M DB9-M
(SHIELD)-+-------------(SHIELD)
+--------------------------------(SHIELD)
TX 2-----+---------->2
+----------------------------->3
RX 3<-+--------------3
+<--------------------------------2
GND 5-----+-----------7
+------------------------------5
4,6,20 4,6,7 <--SHUNTED
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3.4. Project #4: HP48 - Building the adapter for cable F1015-80002.
What you need: some wires, a DB9-M and DB25-M connector (or two DB9-M connectors if your modem uses it) and the HP serial PC-Link cable. In this section I'm referring to older models of cable (like F1015-80002). For newer cables (like F1897, F1207B or 8120-6736) see section 3.3. For using this cable with the HP49G see next section.
NEVER (**NEVER**) plug this cable directly into your DB9 modem. You could damage it!
To use this cable you need to build a DB9-DB25 adapter (or DB9-DB9 if your modem uses a DB9 connector).
Using the adapter.
+----------+ +-----------+ +---------+ | HP48 |<-----------------><--| ADAPTER |-->| MODEM | +----------+ PC-LINK +-----------+ +---------+
Schematic of the adapter:
(TO PC-LINK) (TO MODEM) (TO MODEM)
DB9-M DB25-M DB9-M
(SHIELD)-+-------------(SHIELD)
+--------------------------------(SHIELD)
TX 2-----+---------->2
+----------------------------->3
RX 3<-+--------------3
+<--------------------------------2
GND 5-----+-----------7
+------------------------------5
4,6,20 4,6,7 <--SHUNTED
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3.5. Project #5: HP49 - Building the adapter for cable F1015-80002.
What you need: some wires, a DB9-M and DB25-M connector (or two DB9-M connectors if your modem uses it) and the HP serial PC-Link cable. In this section I'm referring to older models of cable (like F1015-80002). For newer cables (like F1897, F1207B or 8120-6736) see section 3.3. For using this cable with the HP48 see previous section.
NEVER (**NEVER**) plug this cable directly into your DB9 modem. You could damage it!
WARNING: This cable cannot be used as HP49G PC-Link. But can be used as HP49G-Modem cable by building the adapter below.
To use this cable you need to build a DB9-DB25 adapter (or DB9-DB9 if your modem uses a DB9 connector).
Using the adapter.
+-----------+ +-----------+ +---------+ | HP49G |<-----------------><--| ADAPTER |-->| MODEM | +-----------+ PC-LINK +-----------+ +---------+
Schematic of the adapter:
(TO PC-LINK) (TO MODEM) (TO MODEM)
DB9-M DB25-M DB9-M
(SHIELD)-+-------------(SHIELD)
+--------------------------------(SHIELD)
TX 8-----+---------->2
+----------------------------->3
RX 7<-+--------------3
+<--------------------------------2
GND 9-----+-----------7
+------------------------------5
4,6,20 4,6,7 <--SHUNTED
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Before using your new cable for the first time, check it!
4.1. Testing the HP48-Modem Cable.
No matter what method you've followed. The cable you use MUST have:
HP48-4-F DB25-M DB9-M
SHIELD (1)-+-------------(SHIELD)
+--------------------------------(SHIELD)
TX 2-----+---------->2
+----------------------------->3
RX 3<-+--------------3
+<--------------------------------2
GND 4-----+-----------7
+------------------------------5
4,6,20 4,6,7 <--SHUNTED
4.2. Testing the HP49-Modem Cable.
No matter what method you've followed. The cable you use MUST have:
HP49-10-F DB25-M DB9-M
SHIELD (6)-+-------------(SHIELD)
+--------------------------------(SHIELD)
TX 7-----+---------->2
+----------------------------->3
RX 8<-+--------------3
+<--------------------------------2
GND 9-----+-----------7
+------------------------------5
4,6,20 4,6,7 <--SHUNTED
You need a terminal program to have your HP calculator to talk with the modem.
Most of these programs are FREE and can be found in hpcalc archive:
Running these programs, you'll be able to talk directly with your modem. The same your do when using Telix or HyperTerminal on your PC.
Note that you can get the echo of your chars only if you connect to the modem!
6. Connecting your HP to a remore PC or a remote calculator.
Run your favorite terminal program on the HP calculator.
To dial a number, simply type ATDTnnn (dial-tone) or ATDPnnn (dial-pulse), when nnn is the number you have to talk with.
Example: to dial-tone number 555-1234, type ATDT 5551234 when running terminal.
The welcome-message or login-request will soon appear on the screen.
6.1 Upload/Download files using Kermit protocol.
This is the most interesting feature.
You can download/upload any file from/to remote services, using Kermit protocol.
Be sure you set binary transfer both in local (HP calculator) and in remote (PC, or another calculator).
The trick is to start the process on remote device, using terminal program. Then, quit the terminal program and start the Kermit of your HP to complete the operation. Keeping the modem offhook during all the time.
Then you can re-start the terminal program and close the remote connection.
Kermit official web page is http://www.columbia.edu/Kermit.
6.1.1. Download a file from a remote PC.
Assuming you have logged-in, are running the terminal program, and the remote Kermit-server is called KERMIT.
Prompt> KERMIT ;Start remote Kermit server
Kermit> BIN ;Set to binary. Also used: SET FILE TYPE BINARY
Kermit> SEND FILENAME ;Ask to send a remote file called FILENAME
"Kermit is ready to send FILENAME. Please run your local Kermit client..."
Now you have to quit from your terminal program.
From the stack, type
RECV ;Start local Kermit client
Your Kermit client (built in HP calculator ROM) will download the file in current directory.
Now, restart your terminal program:
"File FILENAME has been sent successfully."
Kermit> QUIT ;quit remote Kermit server
Prompt>
6.1.2. Upload a file to a remote PC.
Assuming you have logged-in, are running a terminal program, and the remote Kermit-client is called KERMIT.
Prompt> KERMIT ;Start remote Kermit client
Kermit> BIN ;Set to binary. Also used: SET FILE TYPE BINARY
Kermit> RECEIVE ;Ask the remote client to wait for a file
"Kermit is ready to receive a file. Please run your local Kermit server..."
Now you have to quit from your terminal program.
From the stack, type
-35 SF ;set to binary
'FILENAME' SEND ;ask to send a local file called FILENAME
Your Kermit server (built in HP calculator ROM) will upload the file to the remote client.
Now, restart your terminal program:
"File FILENAME has been received successfully."
Kermit> QUIT ;quit remote Kermit client
Prompt>
6.2. Connect two HP calculators through the telephone line.
Connect each HP calculator to a standard modem. Then, run a terminal
program on both calculators.
From client calculator, type:
ATA ;Set client-side modem in autoanswer-mode
From server calculator, type ATDTnnn (dial-tone) or ATDPnnn (dial-pulse), when nnn is the phone-number of client calculator.
Client and server calculators will connect to each other.
Now, quit both terminal programs (order is not important)
and type, from the stack:
RECV ;on the client HP.
'OBJECT' SEND ;on the server HP.
Be sure both calculators are in binary mode, and Kermit are configured in the same way.
Client HP calculator will receive the 'OBJECT' from the server calculator.
To hang-up, just type:
ATH0
from the terminal program on both calculators.
After having tested the cable, connect it to the modem, and send some command. For example, ATI0 or ATI3 (get modem status), followed by ENTER. You should read the modem prompt ("OK") on the terminal screen. Otherwise, you have a connection problem.
7.1. "Connection doesn't work. Am I using a wrong modem?".
You can use any HAYES-standard modem. I used successfully an old Hayes 2400 and a newer 3COM Voice-Faxmodem V90-56000. A 2400 modem is enough, and, anyway, 9600bps is the highest speed for the HP serial interface.
7.2. "I connect my HP to the modem, then type ATI0, but nothing happens".
Check the cable, and verify that pins 4,6,20 on DB25 (or 4,6,7 if your modem uses a DB9) are shunted together.
If you are sure the problem is not in the cable, is probably in the modem. Please refer to your modem manual, and check the proper init string.
If you would find a init-string that allows a correct connection between the modem and hp48-terminal, you could save it in the modem NVRAM (see modem manual, the command is usually &W).
7.3. "I get modem prompt, but it doesn't dial the number".
From the terminal program send a the command:
ATX3 <ENTER> ;Ignore line-signal.
7.4. "I can connect a remote server, but then I get no answer on terminal".
It could be a problem with the init-string. Disconnect, and send to modem following AT command:
AT&D0&R1 <ENTER>
then re-try the connection.
7.5. "Files appear truncated after upload/download operations".
It probably depends by the small buffer in HP calculator serial interface. And because there's no handshake between calculator and the modem.
You could force the modem to transmit data with a lower speed. Send the command:
AT&Nx
where x is the speed:
7.6. Other problems -OR- problem persists.
Contact me and explain your problems.
9. Obtaining the last version of this document.
Primary address for this page is: http://www.freeweb.org/computer/enrico/hp2modem.htm
Secondary address: http://studenti.ing.unipi.it/~s172776/hp2modem.htm
PK-zipped version: (16Kb) http://www.freeweb.org/computer/enrico/hp2modem.zip
Text-Only version: http://www.freeweb.org/computer/enrico/hp2modem.txt
10. Contacting the author of this document.
Feel free to contact me for any problem or question.
My E-mail addresses are: