Designing a Practical 64KB RAM Card for the Apple IIe, "64K Imp-RAM"

Some time ago, I designed a small daughter card called RAM Hijacker, a 64KB memory expansion daughter card that attaches to the Apple IIe 80COL text card (Apple Ref:820-0066-A). Quite a bit of time has passed since then, and I decided it was time to revisit the idea and redesign a RAM card specifically for the Apple IIe.

As I mentioned in my earlier project, the 80COL text card (Apple Ref:820-0066-A), which does not have any RAM, is now largely unnecessary... I suspect many people have one (or several) sitting unused in a closet.

But if you don't already have 80COL text card, it's quicker and easier to buy a RAM card specifically for the IIe, but our store didn't have one...I decided to think about what I could design and supply.

So, what RAM card options are currently available for the Apple IIe?

There are some excellent third-party Mega RAM cards on the market... Their hardware design is impressive, and the accompanying configuration software is also very well done. That said, back in the Apple II era, Mega RAM cards didn’t exist at all, so there is very little software that truly takes advantage of such large memory expansions. Applications like AppleWorks or certain DTP software may benefit, but compatibility is limited. The advantage of the Mega RAM card is that it makes the computer look more upgraded, which makes the owner very happy. However, in the world of vintage computers, it's more of a pastime than a practical use, so I think it's a great thing for people.

How do most of us actually use an Apple IIe today?

In many cases, it’s for running games and verifying that the system works correctly. When it comes to Apple II games, even later-generation titles typically top out at 128KB of RAM. In fact, I personally don’t know of any Apple II games that require more than that.

Based on this, I felt that there was little practical need to design anything beyond a 64KB RAM card, which brings the Apple IIe to its well-known 128KB configuration. However, I was curious to see which software actually accesses the full 128KB in real-world use.

To investigate this, I modified my RAM Hijacker design by adding an LED that lights up only when the system accesses the upper 128KB memory space. I then booted Total Replay using my SPIISD interface.(The base of my design is Apple genuine 80COL card 820-0066-A with the RAM Hijacker installed.)

Surprisingly, during normal Total Replay operation, the system runs almost entirely within 64KB. Access to the full 128KB is rare. The LED flickers during double hi-resolution graphics or 80-column operations, and even most programs that exceed 64KB tend to move data back and forth between main and auxiliary memory rather than using the full space continuously.

A very clear example is Prince of Persia—when playing it, the LED flashes frequently, indicating active use of the upper memory.

Hardware Design

The card is designed as shown in the photos. Since this is a 64KB expansion, it uses two 16K×4 DRAM chips, along with just two logic ICs. This configuration closely resembles many classic clone RAM cards, which typically used either this arrangement or eight 4264 (16K×1) DRAM chips. Besides Apple’s own solution, several companies released similar 64KB cards back in the day.

After discussing the project with Drake, we decided to name it the 64K Imp-RAM Card.

An Imp is not as large or imposing as a Devil—it’s a small mischievous creature. In my mind, “Imp” means a small helper. This card adds just enough RAM to bring the Apple IIe to its 128KB sweet spot—no more, no less.

I chose to use SMD components to give the design a slightly modern feel. The result is a very clean and compact layout, and I’m extremely happy with how it turned out.

Prototype

Philosophy

Our goal is to offer this card at a very affordable price. In the United States, there are still plenty of Apple IIe systems around. In Japan, 64KB RAM cards occasionally appear on Yahoo Auctions... but they are relatively rare and often priced unreasonably high.

The Apple IIe represents a childhood dream for me. It was the computer I wanted most—its iconic case design, its imposing presence, and its surprisingly empty yet highly expandable logic board all reflect an incredible amount of ingenuity. Thanks to my friends, that dream became reality, and by designing and building the internal components myself, the experience has gained even more depth and meaning.