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HP Forum Archive 07

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HP71b modules - what are they ?
Message #1 Posted by John Robinson on 6 Dec 2001, 8:06 p.m.

I have two HP71b ROM modules labelled "CMT71-64E". Can anyone tell me what these might be ?, and are they useful to anyone ?, and can ROM modules be converted in to RAM modules by replacing the chip inside ??? Thanks - John

      
Re: HP71b modules - what are they ?
Message #2 Posted by Raymond Hellstern on 7 Dec 2001, 3:07 a.m.,
in response to message #1 by John Robinson

Hi,

I don't think you can replace ROM by RAM there, because ROM is read-only, whereas RAM is read-and-write. So there may be an other circuit layout.

Nevertheless there were 64K RAM modules for the card reader port of the HP-71.

Regards,

Raymond

            
'E' for EPROM
Message #3 Posted by Mike on 7 Dec 2001, 9:24 p.m.,
in response to message #2 by Raymond Hellstern

This is an EPROM device.

They also made 64K RAMs for the front plug-in ports.

      
Re: HP71b modules - what are they ?
Message #4 Posted by Bill Wiese on 7 Dec 2001, 3:14 a.m.,
in response to message #1 by John Robinson

I'd bet these are aftermarket modules made by Corvallis Micro Technology due to CMT prefix..

I'd guess "CMT71-64E" is a 64k*bit* (meaning 8k byte) RAM module just because I remember them making 71B stuff, and I don't recall them making any 71B ROMs.

-Bill Wiese -San Mateo, CA

            
Sure they made ROMS
Message #5 Posted by Mike on 7 Dec 2001, 9:21 p.m.,
in response to message #4 by Bill Wiese

I suspect that if you look at the ROM, you will see the UV window on the device.

The 64E is a UV erasable EPROM.

                  
Re: Sure they made ROMS
Message #6 Posted by John Robinson on 9 Dec 2001, 6:32 p.m.,
in response to message #5 by Mike

You're right, there is a window on them. So I guess they're 64K UV EPROMS from Corvalis Micro Technologies. So the contents are presumable useless (to me at least). So, any ideas on how you program the little suckers ??. Can another ROM be copied into them etc ??? Thanks - John

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