<div dir="ltr"><div dir="ltr">On Wed, May 27, 2026 at 3:14\u202fPM vom513 via rescue <<a href="mailto:rescue@sunhelp.org">rescue@sunhelp.org</a>> wrote:<br></div><div class="gmail_quote gmail_quote_container"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">> On May 27, 2026, at 2:30\u202fPM, Dave McGuire via rescue <<a href="mailto:rescue@sunhelp.org" target="_blank">rescue@sunhelp.org</a>> wrote:<br>
> <br>
> Your logic is sound and ordinarily I'd agree with your point. But many early Suns were shipped with ESDI drives and Emulex MD21 SCSI->ESDI adapters, and MFM drives with Adaptec ACB4000 SCSI->MFM adapters. Nobody called them "emulators\u201d.<br>
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Would this be considered an \u201cinterposer\u201d ? I watch a fair amount of vintage computer youtubers and hear this term. I feel like Adrian\u2019s Digital Basement mentioned it regarding his m68k based UNIX machine (Plexus).<br></blockquote><div><br></div><div>Interposers are typically devices with minimal logic to support connecting one device to another where form factors or connector types are physically incompatible, and often where the device being adapted by the interposer has a functional subset of the standard. For instance a SAS to SATA interposer allows the use of SATA devices on a SAS controller. SATA devices have a subset of the SAS standard. There are no interposers for using SAS devices on a SATA controller because the SAS device has a superset of the SATA controller's features. I'm not super-familiar with ESDI, but looking it up in Wikipedia, they mention, "many high-end SCSI drives of the era were actually high-end ESDI drives with SCSI bridges integrated on the drive."</div><div><br></div><div>Bridge is the correct term for that I think, and interestingly that links to the Wikipedia entry for "Protocol converter":</div><div><br></div><div><a href="https://en.wikipedia.org/wiki/Protocol_converter">https://en.wikipedia.org/wiki/Protocol_converter</a><br></div><div><br></div><div>While modern SCSI emulators might be thought of as bridges/protocol converters, that is only one part of what they do. Modern SCSI emulators are highly configurable and support a wide range of physical device emulation, can present many emulated SCSI devices which are all stored on one modern device such as an SD card, and have specific user-configurable controls over how the emulated SCSI devices are being presented to the host and often include other ways to interface with the SCSI emulator outside of the host, all of which define it as something much greater than a mere protocol converter.</div><div><br></div><div>- Nate</div></div></div>