AMD AM27C256-150DC 256K CMOS UV EPROM 28-Pin Ceramic DIP Used

AMD AM27C256-150DC 32K x 8 CMOS EPROM 150ns CerDIP-28

Condition

Used. Evaluated by visual inspection only; function testing not performed. Sourced from prior inventory: programmed but never installed into equipment. Markings legible: AM27C256 -150DC. Sold each.

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Product Overview

AMD AM27C256-150DC is a 256-kilobit ultraviolet-erasable programmable read-only memory organized as 32,768 words by 8 bits. Fabricated using CMOS technology, it operates from a single +5V power supply and offers a 150 ns access time. The chip is housed in a standard 28-pin windowed ceramic dual in-line package (CDIP-28) with 600-mil row spacing, allowing erasure under ultraviolet light for reprogramming. Standard dual-line control pins (separate Chip Enable and Output Enable) simplify bus interfacing and eliminate bus contention in legacy microprocessor and microcontroller systems.

Key Features

• 256K density configured as 32,768 x 8-bit bytes
• 150 ns maximum access time
• Standard +5V operating supply voltage
• Windowed 28-pin ceramic dual in-line package (CDIP-28) with transparent quartz lid
• JEDEC-compliant standard 28-pin DIP footprint (600 mil)
• CMOS architecture with TTL and CMOS compatible inputs and outputs
• Two-line active-low control inputs (CE# and OE#)

Applications

• Restoring firmware ROMs in vintage arcade hardware, synthesizers, and retro computing boards
• Socket replacement for 28-pin ROMs and EPROMs in industrial automation controllers and test benches
• Burning custom maps and tuning code for classic automotive engine management modules
• Breadboarding and bench prototyping with 8-bit microprocessors such as the Z80, 6502, or 8085

Frequently Asked Questions

Does this EPROM come erased or programmed?

The unit was programmed by a previous owner but was never installed into circuit. Because it features a clear quartz window, it can be erased using a standard ultraviolet EPROM eraser before reprogramming.

Can this part directly replace a standard 27C256 or 27256?

Yes. The AM27C256-150DC conforms to the standard JEDEC 28-pin DIP pinout for 256K EPROMs, operating on +5V with a 150 ns speed rating.

What condition is this chip in, and has it been tested?

This chip is used surplus that was programmed by a prior owner but never installed into equipment. Visual inspection confirms intact ceramic housing and straight pins; functional testing on a programmer has not been performed.

Nothing quite matches the satisfaction of sliding a ceramic, windowed DIP into a socket and watching a dormant 8-bit machine flicker back to life. Clear the window, burn your byte table, and bring the board back online.