HP Forum Archive 15

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HP71B- Main Machine Message #1 Posted by John Kercheval on 13 Feb 2006, 2:16 p.m. Hello: Like many of you, I own numerous high end HPs. After all of these years, my "service revolver" is still the 71B with CMT massive RAM chip, HP41 Translator Pac, Finance Pac, and Statistics Pac. Any other 71B users out there? Is CMT still around? John K. in DC

Re: HP71B- Main Machine Message #2 Posted by Garth Wilson on 13 Feb 2006, 3:41 p.m., in response to message #1 by John Kercheval I called CMT a couple of years ago to ask about the lithium batteries in my 71's 96KB card-reader port RAM and 64KB front-port RAM. It seemed like there was nobody left there who even knew what an HP-71 was.

Re: HP71B- Main Machine Message #3 Posted by John Kercheval on 14 Feb 2006, 10:39 a.m., in response to message #2 by Garth Wilson Wow. I have a 32KB card reader port memory module and did not even know it had a battery. Does it? Considering I've had it since 1984 and never replaced a battery I think it is due! However, I've never lost memory. What does the battery do? VERY interested in your response. John Kercheval Georgetown University Washington, DC

Re: HP71B- Main Machine Message #4 Posted by Valentin Albillo on 14 Feb 2006, 11:36 a.m., in response to message #3 by John Kercheval Hi, John: John posted: "However, I've never lost memory. What does the battery do?" If I'm not wrong, it keeps the contents undisturbed when the module is *unplugged*. As long as it remains plugged in, the HP-71B batteries keep its contents nice and tidy. This same concept was extensively used in RAM cards for SHARP handhelds as well, and it allowed their owners to send complicated programs to and fro by simply exchanging cards. It was also useful for backup purposes, of an important application, say. If you're that interested in the HP-71B and you haven't seen them yet, may I suggest you have a look at my HP-71B related articles/programs for this wonderful machine, available on-line as PDF documents from my web site. Best regards from V.

Re: HP71B- Main Machine Message #5 Posted by John Kercheval on 14 Feb 2006, 1:22 p.m., in response to message #4 by Valentin Albillo Will do. I thought that's what the battery did. Where is it? How do you replace the battery. I'll check out your website. John K. DC

Re: HP71B- Main Machine Message #6 Posted by Garth Wilson on 14 Feb 2006, 2:06 p.m., in response to message #5 by John Kercheval You can get to the CMT card reader port RAM battery by removing the port cover, and removing a couple of screws holding the back of the RAM unit on. The battery is soldered in. You don't have to remove the RAM from the computer to access the battery. CMT made these card reader port RAMs up to 160K. There was someone who would hard-wire 256K into the computer for a hefty fee so that you'd still have all your ports available.

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