Donor challenge: Your generous donation will be matched 2-to-1 right now. Your $5 becomes $15! Dear Internet Archive Supporter,. I ask only. Details, datasheet, quote on part number: DESCRIPTION The a 65, bit UV erasable and electrically programmable memory EPROM. It is organized. High speed performance. – ns access time available. • CMOS Technology for low power consumption. – 20 mA Active current. – µA Standby current.
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Storing data in the memory requires selecting a given address and applying a higher voltage to daasheet transistors. This creates an avalanche discharge of electrons, which have enough energy to pass through the insulating oxide layer and accumulate on the gate electrode. Once complete, most software allows you to verify that the image in the EPROM is now the same as the one in the ratasheet. Because higher-density parts have little exposed oxide between the layers of interconnects and gate, ultraviolet erasing becomes less practical for very large memories.
A programmed EPROM retains its data for a minimum of ten to twenty years,  with many still retaining data after 35 or more years, and can be read an unlimited number of times without affecting the lifetime. The recommended erasure procedure is exposure to UV light at Don’t look directly at the bulb when the door is open.
2764A – 2764A 64K EPROM Datasheet
What you need to do will differ depending the machine. An insulating layer of oxide is grown over the channel, then a conductive silicon or aluminum gate electrode is deposited, and a further thick layer of oxide is deposited over the gate electrode. For example, one manufacturer might use 21vpp for their ICs whereas another may use 25vpp.
Cambridge Epdom Press, p.
The switching state datasheett the field-effect transistor is controlled by the voltage on the control gate of the transistor. Typical values are 25v, 21v or A control gate datashet is deposited and further oxide covers it. Even dust inside the package can prevent some cells from being erased. This page was last edited on 8 Novemberat The effects of this process on the reliability of the part would have required extensive testing so they decided on the window instead.
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Source and drain contacts are made to regions at the end of the channel. I had a Willem but it died so my current programmer is a Top out of China fig 3.
It seems to work well, although at the time of writing the manual for this Chinese device appears to have been written using an early version of Google Translator! Often this label was foil-backed to ensure its opacity to UV. Datasneet couple of VCF folks helped me refine this article.
IC Datasheet: EPROM : Free Download, Borrow, and Streaming : Internet Archive
First rule is to know the kind of EPROMS you want or are likely to want to burn and get a programmer that can handle them. Some EPROMS don’t have a window and are not erasable even though they have the same part number as the erasable version. Exposure time for sunlight of one week or three years for room fluorescent lighting may cause erasure. Typically, my eraser will blank a chip in about 20 minutes. The floating-gate electrode has no connections to other parts of the integrated circuit and is completely insulated by the surrounding layers of oxide.
Since the whole memory array is exposed, all the memory is erased at the same time.
The Willem requires you to set jumpers and dip switches whereas my TOP allows chip selection from software. These have a “C” between the prefix and size number e.
IC Datasheet: 2764 EPROM
Development of the EPROM memory cell started with investigation of faulty integrated circuits where the gate connections of transistors had broken. For large eprlm of parts thousands of pieces or moremask-programmed ROMs are the lowest cost devices to produce.
For your average vintage microcomputer, EPROMS can be recognised by their clear transparent windows, normally covered by some kind of label. Try 20 minutes first and if that doesn’t fully erase the chip try again with a longer interval until you find a datasheeg span that does. Once programmed, an EPROM can be erased by exposing it to strong ultraviolet light source such as from a mercury-vapor light. It may even check automatically.