XRX - eXperimental Research X

If one of the goals of this project was to avoid using obsolete components, one of the biggest problems revolved around the VDP.

The V9958 itself hasn’t been manufactured for decades, so I’d have to use whatever I could buy from more-or-less-honest brokers. But I didn’t want to do the same with the DRAM modules used with it.

“How hard can it be?”®

It’s not an original idea; this has been done before. 

The first attempt had a small glitch, of course... but in the end I still managed to save one chip compared to Tom LeMense’s implementation.

### Zilog Z380

The Z380 was introduced to the American market in 1994 by Zilog as an extension (and instruction set compatible) of the successful Z80. However, it had already been shipping to Japanese customers for a year before that but unfortunately none of them were willing to use it in an MSX-compatible machine. 

Here is a small table comparing the different Zilog processors at the time:

Zilog's original documents mention speeds of up to 40MHz, but I could only find the 18MHz version. We will not discuss the Z382 version, even more difficult to find these days.