> On Oct 5, 2017, at 2:53 AM, Christian Corti via cctalk > <cctalk@classiccmp.org> wrote: > > On Wed, 4 Oct 2017, Guy Sotomayor Jr wrote: >> Also, the early desktop PS/2 (model 50 and such) had the controller >> integrated on the drive and those were Maxtor as I recall. The PS/2 shipped >> in 1987 and we had the drives in labs at least 12-18 months prior (memory is >> dim on this right now). > > No. The IBM 8550 has the controller on a special card and the drive had a PCB > edge that inserted into the PCB connector on the side of the controller. The > 8550-021 used a 20MB IBM WD-325N disk drive (P/N 90X6806). The controller is > a ST-506 type MFM controller (with DMA, so it rocks with a sustained data > rate of above 500kB/s!). My father upgraded the system with a standard > Rhodime 50MB MFM drive. There was a purely passive adapter that split the > card edge connector into the normal 20+34 pin connectors plus power. I still > have that system and drive :-) >
OK, my recollection must be faulty since I thought that the “riser” was passive e.g. just some connectors for HDD and floppy, traces and plugged into the motherboard. There were a number of different drives. I don’t recall the 20MB drive. I mostly saw 60MB and 120MB drives. TTFN - Guy
