Hi Thank you for a most interesting reply. Despite having been around when the transitions between interface types happened, there was a lot I did not know. The fact that the ST506 interface was derived from 8" floppy technology was news to me. I collect DEC equipment and all of the MFM drives DEC sold were OEM badge jobs. There were three DEC RQDX MFM controllers I know of. I have a RQDX-1 and a couple of RQDX-3's. I have never seen a RQDX-2. All three are for the Q-bus. I have a few RD-53's but only one is reliable. The main logic board in an RD-53(Micropolis 1325) has a 8051 and a bunch of other stuff. I can't see how an interface board with an 8051 is regarded as dumb. I am not short of SCSI drives in assorted physical sizes, capacities and interface types. I also have a couple of third party Q-Bus SCSI controllers. Stating the obvious the above only applies to PDP11's. Yes I know you can put a Q-bus controller in a Q-bus VAX. So what's my problem? As with many collectors my goal is to get the systems back to the state they were in when they left the factory. I start with the model designation on the box label and try to restore back to what that defined. I'll stretch a point insofar as I'll use any MFM drive that DEC bought the OEM version of regardless of if came from DEC. Even allowing for that MFM drives that RQDX controllers can handle are getting scarce. So the problem is how the make an RQDX controller think its talking to an RD series MFM drive when it isn't. ? Rod Smallwood (G8DGR) ? -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Andrew Lynch Sent: 28 February 2011 00:18 To: cctalk at classiccmp.org Subject: RE: SCSI -1 to IDE and SD project Hi Rod, I do not think an MFM/RLL (ST506/ST412) to IDE bridge board is feasible. The SCSI-1 and IDE interfaces are purely digital and the drives are intelligent enough to abstract much of the realtime complexities of communicating with the hard drive itself. As a result the bridge board between the SCSI-1 and IDE is relatively simple and a basic Z80 embedded controller is able to accomplish the data transfer relatively easily. It is well suited for a community hobbyist project like the SCSI to IDE/SD bridge board we are working on at Vintage-Computer.com forums. MFM/RLL (ST506/ST412) interfaces are a high speed extension of the Shugart floppy drive interface with some additional signals. It is a hard realtime interface and low level way to communicate with the hard drive. As a result it would require an extremely sophisticated high speed controller to interpret the signals to and from the MFM/RLL (ST506/ST412). A simple Z80 or microcontroller based controller would not be able to accomplish the task in my opinion. It may be possible but I believe it would be an expensive commercial device and probably quite rare. The SCSI-1 to/from IDE/SD project is a hobbyist community project and I think would be quite helpful to the wide array of legacy/vintage/classic devices which use SCSI-1 drives. So far, I have heard from owners of the obvious microcomputers like Atari, Amiga, Apple Mac, Sun workstations, DEC, etc. However many other devices used SCSI-1 devices such as synthesizers, a variety of test and lab equipment (?), sewing machines (?), photocopiers (?), and other devices I would have never suspected used SCSI-1 drives. At the moment, there are 6 builders with the prototype PCBs but none have reported a working build yet. The parts are very common and the design uses only "hobbyist friendly" construction for easy assembly. However, the software still needs to be written which should be largely reuse of existing Z80 code from existing N8VEM projects. If you or anyone else is interested in working on the project please contact me. I still have 4 remaining prototype PCBs. My goal is to get this project up and running before the SCSI-1 drives become difficult to obtain such as 100 TPI floppy drives, MFM/RLL (ST506/ST412) hard drives, and other uncommon storage medias. All of the technical information on the project is available at the N8VEM wiki. It will be free/open and publicly posted for community benefit like the rest of the N8VEM boards. Please read the existing technical documentation before critiquing the design. http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder <http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=MINI%20SCSI%20 to%20IDE%20prototypes> &param=MINI%20SCSI%20to%20IDE%20prototypes Thanks and have a nice day! Andrew Lynch SCSI -1 to IDE and SD project Rod Smallwood rodsmallwood at btconnect.com <mailto:cctalk%40classiccmp.org?Subject=Re%3A%20SCSI%20-1%20to%20IDE%20and%2 0SD%20project&In-Reply-To=%3C5177DAA49B624EFD819C07F9E41EFFA8%40RODSDEVSYSTE M%3E> Tue Feb 22 02:36:34 CST 2011 * Previous message: GSX <http://classiccmp.org/pipermail/cctalk/2011-February/297266.html> porting project * Next message: SCSI -1 to <http://classiccmp.org/pipermail/cctalk/2011-February/297278.html> IDE and SD project * Messages sorted by: [ date ] <http://classiccmp.org/pipermail/cctalk/2011-February/date.html#297263> [ <http://classiccmp.org/pipermail/cctalk/2011-February/thread.html#297263> thread ] [ subject ] <http://classiccmp.org/pipermail/cctalk/2011-February/subject.html#297263> [ author ] <http://classiccmp.org/pipermail/cctalk/2011-February/author.html#297263> _____ Hi This looks interesting. As collector of DEC systems my need is slightly different insofar as due to the rapid disappearance of ST506 (MFM) drives I need to make say an IDE drive look like a an ST506 drive to a DEC MFM controller. Whilst your SCSI to IDE is nice I'm not short of SCSI drives. However with your experience you might like to comment on if you think a DEC MFM controller to IDE drive converter box is feasible. Regards Rod Smallwood -----Original Message----- From: cctech-bounces at classiccmp.org <http://www.classiccmp.org/mailman/listinfo/cctalk> [mailto:cctech-bounces at classiccmp.org <http://www.classiccmp.org/mailman/listinfo/cctalk> ] On Behalf Of Andrew Lynch Sent: 21 February 2011 14:39 To: cctalk at classiccmp.org <http://www.classiccmp.org/mailman/listinfo/cctalk> Subject: SCSI -1 to IDE and SD project Hi! Several weeks ago there was a discussion on CCTALK about a free/open SCSI to IDE and SD project. I designed a PCB using the Z53C80 and a Z80 with RAM/ROM/UART/IDE and SD. There is a prototype available waiting for some interested builders to take on the project. As far as I know none of the builders have a completed unit although I think if we had at least one working unit the project would make some real progress. I have four remaining SCSI to IDE/SD prototype boards so if anyone would like to join the project as a software developer please let me know. I believe much of the software can be reused from previous N8VEM and/or other free/open software projects. http://n8vem-sbc.pbworks.com/w/page/35044530/PCB-Inventory Thanks and have a nice day! Andrew Lynch _____ size=2 width="100%" align=center> * Previous message: GSX <http://classiccmp.org/pipermail/cctalk/2011-February/297266.html> porting project * Next message: SCSI -1 to <http://classiccmp.org/pipermail/cctalk/2011-February/297278.html> IDE and SD project * Messages sorted by: [ date ] <http://classiccmp.org/pipermail/cctalk/2011-February/date.html#297263> [ thread ] <http://classiccmp.org/pipermail/cctalk/2011-February/thread.html#297263> [ <http://classiccmp.org/pipermail/cctalk/2011-February/subject.html#297263> subject ] [ author ] <http://classiccmp.org/pipermail/cctalk/2011-February/author.html#297263> _____ More <http://www.classiccmp.org/mailman/listinfo/cctalk> information about the cctalk mailing list _____