> On Jun 10, 2026, at 10:37 PM, Fred Cisin via cctalk <[email protected]>
> wrote:
>
> ...
>> One peculiar aspect of the RAMAC is that it only had one head, or one pair,
>> so track switching was a lot slower than cylinder switching: it had to
>> retract all the way, then move the head vertically to the correct track,
>> then seek in again to the right cylinder.
>
> As opposed to ST225, with 4 heads for one platter. :-)
CDC did that first, with the 6603 in 1964 or so, giving them a crazy high data
rate for the time. I think it was 12 bits parallel per track (matching the PPU
word width) but perhaps it wasn't quite that many.
I vaguely remember that Cray did the same thing with the Cray-1.
paul
