-----Original Message----- From: David Gesswein <djg(a)drs-esg.com> The RX28 added DMA, the RX02 drives while the same physical disk drive (bare) the two controller cards are very different. The older RX01 used TTL of the 7489 and 74181 for its controller while the later RX02 was 2901/2911 based. Allison