[ Maynard, Massachusetts ]: Digital Equipment Corporation. Measures approximately 10 1/2 x 8 1/4 inches. The card on the front has stickers from Electronic Memories. On one side on the very edge it notes "Planar Stack Board" and on the other G619A. On the front the card notes "Flip Chip (R)" and above that the date Jul 16, 1971 is stamped. On the rear we inked on the board is "DEC H-220", EM P/N 912591-A02, EM S/N 75301, Date Code 47-71 and a number "17522 100 222 FW" Good. 
An early DEC computer memory card. It is very, very cool, and would look great framed if you added a magnifier built in to see the small cores!!!. We have no way to test it so it is being sold as is, as a historical computer artifact. These are getting a lot harder to find, as most were scrapped years ago for metal content.
"Flip Chip" which was a module used by Digital Equipment Corporation starting in 1965. It is a core memory card, with many, many small ferrite cores each with wires threaded through them. There are 24 banks of cores.
We found a PDP-8 manual online that notes the following about the G619 card:
"G619 Planar Stack Board
The basic 4K memory stack consists of 4096 12-bit words of memory, along with the X-axis and Y-axis diode selection matrix.
It also contains a thermistor that supplies temperature information to the XY current control circuit. The core array is a 3-dimensional, 3-wire memory with center tapped sense/inhibit wire. The same memory stack module is also used in the memory parity option. It has no important connections to or from the OMNIBUS."
Another internet site for the PDP 8 notes the following:
"G619 MM8E Memory stack
G619A MM8E Memory stack (B,M)"
From wikipedia :
"The 12-bit PDP-8, produced by Digital Equipment Corporation (DEC), is the first successful commercial minicomputer. DEC introduced it on March 22, 1965 for a price of US$18,500, and eventually sold more than 50,000 systems, the most of any computer up to that time. It was the first widely sold computer in the DEC PDP series of computers (the PDP-5 was not originally intended to be a general-purpose computer). The chief engineer who designed the initial version of the PDP-8 was Edson de Castro, who later founded Data General.
The earliest PDP-8 model (informally known as a "Straight-8") used diode-transistor logic, packaged on flip chip cards, and was about the size of a small household refrigerator.
This was followed in 1966 by the PDP-8/S, available in desktop and rack-mount models. By using a one-bit serial arithmetic logic unit (ALU) implementation, the PDP-8/S was smaller, less expensive and slower than the original PDP-8. The PDP-8/S was about 20% of the cost and about 10% of the performance of the PDP-8. The only mass storage peripheral available for the PDP-8/S was the DF32 disk.
Later systems (the PDP-8/I and /L, the PDP-8/E, /F, and /M, and the PDP-8/A) returned to a faster, fully parallel implementation but used much less costly transistor-transistor logic (TTL) MSI logic. Most surviving PDP-8s are from this era. The PDP-8/E is common, and well-regarded because so many types of I/O devices were available for it. It was often configured as a general-purpose computer."