< At the time, MITS had an absolutely miserable 4K dynamic memory board. < This was one of the few ways that they could entice folks to buy it. The 88MCD was poor, the S4K slightly better and neither would work with z80s without being severely hacked! I had three of each and they were all junk. Why three of each... at one point S4Ks were offered less rams to anyone that had 88MCDs at a ok price. I was able to make them acceptably reliable by pulling the Drams and putting in compatable static parts (NEC uPD410). The board layout still stank and the general noise level on the bus didn't help. Up grading the bus to a WAMCO or compupro with terminations helped. Replacing the whole machine with a NS* Horizon was a vast step forward. Allison