Path: utzoo!attcan!uunet!cs.utexas.edu!sun-barr!newstop!exodus!texsun!letni!doug From: doug@letni.UUCP (Doug Davis) Newsgroups: comp.sys.tandy Subject: Re: 16B Info/Tips/Resources (semi-long) Summary: nits Keywords: 16B, Xenix, Tandy Message-ID: <13154@letni.UUCP> Date: 12 Sep 90 20:15:22 GMT References: <1990Sep12.073838.8635@coyote.uucp> Organization: Logic Process Unix Engineering, Dallas Office Lines: 107 Just a few clarifications in an otherwise very good article. In article <1990Sep12.073838.8635@coyote.uucp> jmh@coyote.UUCP (John Hughes) writes: > >In order to keep this as short as possible, I am not going to take >up bandwidth with diagrams and such. As far as I know, the service >manuals I refer to below are still available from Radio Shack. If >you intend on keeping your 16B for a while, buy them. They are available in a limited degree from Tandy National Parts 817-870-5662, who accept M/C Visa and a few others. >What the Model 16 Is, and Is Not >Peripheral Devices and Enhancements > >The stock 16B, right out of the box, will support up to four 8" >floppy drives. These may be either single-side or double-side. >Tandy also had some other interesting stuff available, and here is >a list from reference 1: > >External Floppy Disk Expansion Bay - 1 drive and 2 drive models In single sided Model II drives you could get a cabinet with up to three drives. In the double sided model 16b/6000 drives expansion was via a 1 or two drive cabinet. >External Hard Disk Unit - 12 and 15 Mbyte units 35 and 70 Mbyte units were also sold. >ARCNET interface system Useless under Xenix... >I have also heard mention of a cartridge tape subsystem. It shows >up as a 'diskutil' menu selection, but I've never seen one. It's not a "tape" cartridge system but an IOMEGA bournelli(sp?) system with one or two, 10 or 20 meg cartridge drives. The interface board on this had a resimblence to SASI.. The rumor mill has it that Bob Snapp has developed drivers for real live SCSI style devices for use with this interface board. Unfortunatly these apparently only work with the older 3.1 Xenix. >16B Hard Drives >There are two types of external hard drive controllers, both of >which require an interface card in the 16B. This interface is not >simply an extension of the Model I expansion bus. It is SCSI, or >something very close to it. No it isn't, the only thing close to SCSI that comes out the back of the II/12/16/6000 machines is the IOMEGA interface. The expansion may look like it as some of the signals that a SCSI interface has but it ain't SCSI. Its a very uncompatable propriatary expansion interface it resembles the model I/III/IV interface in its physical charicteristcs. This interface like the IOMEGA interface was entirely driven by software. (yes, with icky timing loops and everything.) >Since I've never fiddled with the 8x300 card, I can't make >definitive statements about it. From the PCB layout drawings, >however, it is apparent that there are connections for up to four >ST506 MFM drives. On that basis I will assume that what one can do >with a WD1000, can also be done with the 8x300. Note that I also >cannot speak for what the different rev's of Tandy Xenix think >about these cards. I run 3.02, and have never bothered to install >the version 1.something or other that I also have (I mean, like, >why bother?). Almost, the ST506 interface is a REAL st506 interface, not the 421/412 that you get on a PeeCee. Be carful when interfacing drives with it, one of the signal lines is different (I forget which one) and is usually shunted to ground. >The maximum size per disk drive is 8 heads and 1024 cylinders. If >you max out all four drive ports you can amass a respectable amount >of mass storage. One VERY IMPORTANT note here: try to get a list of >where the disk media defects are *before* you format the drive. >diskutil will ask for it, and I don't know if the low-level format >is capable of detecting flaws in the platter surfaces. If the drive >you have does not have the defects list taped to it, then you might >try temporarily installing the drive on a PC and running something >like Gibson's SpinRite on it. Kludgy, but it will work. diskutil can and will detect flaws in the surface, but even it isn't 100% accurate all the time. If you don't have the error map, putting on a PeeCee and running the above mentioned program is a good idea, as well as running diskutil with full verify. >Many of the older 16B systems (if not all) used single-sided >floppies. All 16B systems were double sided, perhaps you are refering to a 16A? >16B I/O Ports >The stock 16B comes with two serial and one parallel port. The >serial ports may be configured to operate at up to 9600 baud. The >parallel port is Tandy-standard, which means a parallel cable for >a PC will not work. I made my own cable, but I have a hunch that >the printer cable from a Model III will also suffice. No a model III cable is an edge card, like a model 1 cable, neither of these will suffice. Last time I looked a 6' cable for the II/12/16/6000 machines was around 35 bucks, at Radio Shack. doug __ Doug Davis/4409 Sarazen/Mesquite Texas, 75150/214-270-9226 {texsun|lawnet|smu}!letni!doug doug@letni.lonestar.org "Be seeing you..."