Computer Museum news about computers, microcomputers, hobbyist, robotics, computing, Bugbooks, Computers in the Bugbook Historical Computer Museum collection, & amateur radio staion N4USA .

Saturday, June 27, 2015

EPROM - Erasable Programmable Read Only Memory - computer memory



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info click
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1702A EPROM
The first (1971) EPROM ( Erasable Programmable Read Only Memory ) 1702A changed computing forever. The 1702A is  Nonvolatile memory chip and does not lose its contents (program) when power is turned off.  RAM (Random Access Memory)  used at the time was volatile - the contents is lost every time power was turned off.  Being able to program the microcomputer and have the program or data stay resident when power is turned off was essential. The EPROM was invented by Dov Frohman of Intel in 1971, who was awarded US patent 3660819 in 1972.

Click on photo to enlarge
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1702A EPROM

It is interesting to look though the quartz window of the EPROM integrated circuit (IC) at  the die inside. You can see the little gold wires that connect the die to the pins on the holder.  The quartz window allows the memory to be erased by exposing it to UV light and then it could be reprogrammed. More information about EPROM's "Wikipedia CLICK"



This is a revisit to EPROM's - see my earlier post "Vintage EPROM Memory 1702A -Made microcomputers, robotics and micro-controllers practical 1971 CLICK"


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1987 reciept for 359 EPROM's


In 1987 I purchased a nice collection of 359 EPROM's from Computer Surplus Store for $229.85.  This looks like a good deal today at 50 cents each.




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1987 receipt for 359 EPROM's


Date & Price








Click on photo to enlarge
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1702A 2708 EPROM


Here  are the 359 contained in 30 storage tubes. Almost all the EPROM's are the beautiful ones in a white ceramic package and gold pins.

This shows hoarding as I indicated in my last Blog.




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1702A 2708 EPROM close view
A closer look at some of the 359 EPROM's.

I purchased these 28 years ago with the idea of using them to make a display plaque to put on a desk or hang on the wall. The white ceramic EPROM's with the clear quartz window a very interesting to view and with some additional photographs and history with the EPROM it would be an eye catcher for sure.

You can get a good look by CLICKING on the photo.


As you can see I have not made the displays using the 359 EPROM's and would like some help or suggestion about how to put them good use . Of course I could sell them on Ebay but that would not be much fun. Contact me here with your idea's "Contact David CLICK"

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Some of the EPROM'S  in our inventory are in applications like the board below.
Click on photo to enlarge
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menory card 2716 EPROM
I have hundred's or perhaps 1000's more of the EPROM'S in the museum warehouse. Many are in the nice white package.

Here is a typical use of EPROM's - this board contains (16) 2716 EPROM's . The operational program for this computer is contained in these 16 nonvolatile memory chips. The 2716 contains 16K Byte of memory.

Can someone help me identify this early microcomputer board??


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2716 EPROM



Better view of the 2716 chips on the computer board shown above.






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A small collection of EPROM'S
Click on photo to enlarge
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Intel 1702A EPROM



A small batch of 1702A chips unused in the original Intel Package. The package is also interesting and a collectible item.









Computer Museum Bugbook Bugbooks
Intel 1702A EPROM 



 New unused Intel 1702A EPROM chips.








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Here is a video I made in 2009 about the 1702A EPROM "CLICK"
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Bugbook Historical Microcomputer Museum
David Larsen
I have hundreds of EPROM's in the museum warehouse and many of them are still on computer boards like S100 memory cards. Please help with some innovative and interesting uses for all these beautiful IC's. Still having fun at 76 yrs. 
           ."by David Larsen"  KK4WW Computer Collector Historian