[Coco] SCSI/SASI HD interfaces...

[Francis Swygert]

Date: Fri, 3 Apr 2015 03:03:35 -0400
From: Bill Pierce <ooogalapasooo at aol.com>
To: coco at maltedmedia.com
Subject: Re: [Coco] CoCo 2 Factory Composite Video RE'd

Both Kenton and LR Tech (Owl-Ware) were scsi hard drive systems and were regularly advertised in Rainbow.
============================================
Well, maybe. I don't really know about the Kenton and LR Tech. They may very well be true SCSI interfaces. According to Wikipedia: 

"SCSI was derived from "SASI", the "Shugart Associates System Interface", developed circa 1978 and publicly disclosed in 1981.[2] A SASI controller provided a bridge between a hard disk drive's low-level interface and a host computer, which needed to read blocks of data. SASI controller boards were typically the size of a hard disk drive and were usually physically mounted to the drive's chassis. SASI, which was used in mini- and early microcomputers, defined the interface as using a 50-pin flat ribbon connector which was adopted as the SCSI-1 connector. SASI is a fully compliant subset of SCSI-1 so that many, if not all, of the then-existing SASI controllers were SCSI-1 compatible."
I don't know the differences, but the Disto controllers were SASI and only supported two devices, IIRC. They used less than 50 pins, but I think a lot of the grounds were left out. IIRC SASI/SCSI used alternating grounds (25 grounds, 25 signals). Disto may have dropped some of the signal pins as well. Most of the SCSI controllers for the CoCo only supported hard drives -- not much else was ever used on a CoCo, and it was quite the unusual CoCo user that had more than two HDs connected -- most only had one. 
 
Frank Swygert
Fix-It-Frank Handyman Service
803-604-6548