The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

Guy Sotomayor Jr ggs at
Thu Oct 5 10:57:58 CDT 2017

> On Oct 5, 2017, at 2:53 AM, Christian Corti via cctalk <cctalk at> 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

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