Product Overview
SEEQ DQ27128-20 UV EPROM - 16K x 8 in a Ceramic Quartz-Window DIP28, 200ns, Date Code 8824, NSN 5962-01-359-1151
Condition
Unused NOS. The photographed piece rests on pink antistatic foam, and the white ink marking on the black ceramic body reads cleanly: the lowercase seeq logo, DQ27128-20, and the 8824 date code. The quartz window is clear and unclouded - the macro photo looks straight through it to the die, the gold bond wires fanning out to the lead frame, and the gold-plated seal ring around the glass. All 28 leads are straight and bright with no solder wetting, no oxidation, and no socket marks visible, and the pin 1 notch at the marked end is intact. Data content is unknown - these appear unwritten, but that has not been electronically verified. Sourced from surplus inventory after a company downsizing. Evaluation: visual inspection only. Function testing not performed. Stock is 40 pieces, so the photos show one representative chip and the exact piece you receive may not be the one pictured.
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Product Overview
The SEEQ DQ27128-20 is a 128Kbit UV-erasable EPROM organized as 16K x 8-bit, built in NMOS and housed in a 28-pin ceramic DIP with a quartz erase window. Access time is the 200ns speed grade called out by the -20 suffix, and the device operates from a 5V supply. The 8824 date code places manufacture in week 24 of 1988, and the part carries NSN 5962-01-359-1151, which means this exact package format was once qualified for government and military procurement. Erasure is done by exposing the window to ultraviolet light, after which the chip can be reprogrammed on any programmer that supports the 27128 family. The window on this piece is clear enough to photograph the die itself, which is the same window a UV eraser needs to do its work.
Key Features
- Memory organization: 128Kbit (16K x 8-bit)
- Access time: 200ns (-20 speed grade)
- Package: ceramic 28-pin DIP with quartz UV-erase window
- Technology: NMOS UV EPROM, erasable and reprogrammable
- Supply voltage: 5V operating
- Date code: 8824 (week 24, 1988), legible on the package in the photos
- NSN: 5962-01-359-1151
- Marking confirmed in photos: seeq logo, DQ27128-20, 8824
- Leads straight and bright, window clear, die visible - confirmed by visual inspection only
Applications
- Arcade board restorer reburning a corrupted game ROM in a 27128 socket
- Industrial maintenance tech re-flashing firmware for a 1980s controller that will not accept a modern flash part
- Retro computing builder who needs a period-correct BIOS or character ROM in a DIP28 footprint
- Bench engineer iterating firmware on an older microprocessor board, erasing and reburning between revisions
- Collector or repair shop stocking spare windowed EPROMs before they get harder to find
Frequently Asked Questions
Is there data already written on these chips?
Data content is unknown. They appear unwritten based on sourcing history and visual condition, but nothing has been read electronically here. Read the chip with your programmer before assuming it is blank, and if it comes back with data, a UV eraser will clear it in the usual cycle.
What programmer and eraser do I need?
A programmer that lists the 27128 family and can supply the programming voltage this device expects, plus a UV EPROM eraser for clearing. Check your programmer's device list for DQ27128-20 or a generic 27128 entry before ordering. Programming voltage varies across 27128 variants, so verify against the datasheet before you burn.
Will it drop into a socket built for another 27128?
The DQ27128-20 is pin-compatible with the 27128 family in a 28-pin DIP socket. Confirm two things for your target: that 200ns meets or beats the access time your system needs, and that your programmer handles this variant's programming voltage. Not confirmed here - verify against the datasheet before use.
Does it come with a cover for the window?
No label is included, and none is fitted in the photos. Any windowed EPROM in service wants a UV-opaque sticker over the quartz, because ambient and fluorescent light will slowly bleed charge off the cells over years. The labels are cheap and widely stocked.
Nothing here was powered up or read - what am I actually buying?
You are buying exactly what the photos show and nothing more: a ceramic 27128 with clear glass, clean straight leads, a legible 8824 date code, and no electrical test behind it. We inspected it by eye, we did not burn it, and we did not verify the array is blank. That is the trade for a 1988 windowed part at surplus terms, and for most buyers it is a fair one, since the first thing any 27128 does on your bench is get read and erased anyway. With 40 on the shelf the photos are representative, not a portrait of your specific chip. Shipping is $8 flat rate, free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
Not many parts let you look straight at the silicon that will be holding your code - week 24 of 1988, and the quartz is still clear enough to see right through. Burn it, tape the window, and let it keep working for another few decades.
