Product Overview
Microchip 28C64A-20I/P | 64K CMOS EEPROM, 200ns, Industrial Temp, DIP-28 | Unused NOS
Condition
Unused NOS. Markings legible: 28C64A-20I/P, lot code 9745SKN, Microchip logo on matte black DIP-28 body. Leads straight, no visible damage. Sourced from an electronics distributor consolidating inventory.
Ships same or next business day from our Idaho warehouse. Honest pricing, no nonsense.
Online since 1999. We are here for our customers, with a no-hassle satisfaction guarantee.
Product Overview
Microchip Technology 28C64A-20I/P - a 64K (8K x 8) CMOS Parallel EEPROM in a 28-pin through-hole DIP package. The -20 suffix indicates 200ns access time. The I/P suffix confirms industrial temperature range (-40°C to +85°C) and plastic DIP package. Electrically erasable and reprogrammable without UV light, this chip operates on a single 5V supply and connects directly to a parallel bus - the interface that older microprocessor systems were built around. Production lot 9745SKN places manufacture in late 1997.
Key Features
- 64K capacity organized as 8K x 8-bit
- 200ns access time (speed suffix -20)
- 5V single-supply operation, CMOS technology
- Industrial temperature range: -40°C to +85°C
- 28-pin plastic DIP package - direct through-hole socket fit
- Parallel interface: CE, OE, WE control signals
- Page write capability with data polling verification
- Electrically erasable - no UV lamp required
Applications
- Replacing a failed BIOS or firmware chip in a Z80, 6502, or 68000-based vintage computer - program it with an EEPROM programmer, drop it into the socket, and bring the system back to life
- Loading custom ROM code onto a retro single-board computer or homebrew 8-bit build where the parallel bus interface is already there waiting
- Swapping out a failed configuration memory chip on legacy industrial control equipment where exact pinout and 5V parallel operation are required and a modern serial EEPROM won't substitute
- Storing bootloader or firmware in an embedded system project built around an older parallel-bus microprocessor
- Experimenting with vintage memory architectures - a clean, unprogrammed NOS chip is the right starting point for learning how parallel EEPROMs work in real hardware
Frequently Asked Questions
Will this work as a direct replacement for my original 28C64 or 2864 chip?
The 28C64A is pin-compatible with 28C64 and 2864 parallel EEPROMs in a 28-pin DIP socket. Confirm your system runs on 5V and uses a parallel bus interface. If your original chip was rated faster than 200ns, verify your system can tolerate a 200ns access time before installing.
Does this fit a standard 28-pin DIP socket?
Yes. The 28C64A-20I/P is a 28-pin 0.6-inch wide plastic DIP, compatible with standard through-hole DIP-28 sockets.
Is this chip blank (unprogrammed)?
NOS chips of this type are typically unprogrammed or erased from the factory. Programming requires a compatible parallel EEPROM programmer. Not confirmed for this specific unit - treat it as unprogrammed until verified with your programmer.
What temperature range does this support?
The I suffix in 28C64A-20I/P confirms the industrial grade: -40°C to +85°C. This is the wider-range variant compared to the commercial grade (0°C to +70°C).
Is this compatible with 3.3V systems?
No. The 28C64A requires a 5V supply. It is not compatible with 3.3V or lower-voltage systems without appropriate level translation, which adds circuit complexity and is generally not a practical approach for direct replacement.
A late-1997 chip sitting untouched for decades, still waiting for the right socket. Program it, seat it, and the machine that went quiet has something to say again.
