----- Original Message: Message: 20 Date: Sun, 7 Aug 2011 19:57:39 -0400 (EDT) From: Jeff Jonas <jeffj at panix.com> To: cctech at classiccmp.org Subject: Tony Duell's maxed out 5160 and PDP Message-ID: <Pine.NEB.4.64.1108071922220.6274 at panix5.panix.com> Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed replying to ard at p850ug1.demon.co.uk (Tony Duell) How did you accomplish that? - a controller that honors all 4 drive selects, not just 2 - primary & secondary disk controller - Compaticard or other disk controller at "non-standard" address & IRQ? My pre-PC systems (mostly Z80 CP/M) all support 4 floppies per the original specs. But NOOOOOOOOOOOOOO, the PC's "cable twist" ruined that, limiting things to 2 floppies and 2 hard drives per controller. Not 'till SATA have we been able to un-do that mistake :-( ----- Reply: NOOOOOOOOOOOOOO, as Chuck said, you've obviously lived a sheltered life; the PC & XT supported 4 drives just like your Z80 CP/M boxes, and instead of "ruining" anything, the "cable twist" actually permitted running only one motor at a time instead of needlessly spinning and wearing out the idle disks (since most 5 1/4 drives did not have head load solenoids). As to hard disks, how many of your Z80 CP/M ST412/506 hard disk controllers had provisions for more than two drives? As to other interfaces I think SCSI and IDE (PATA) both allowed more than two drives per controller and predate SATA by quite a bit... m