Path: utzoo!utgpu!watserv1!watmath!att!mcdchg!tellab5!nucsrl!accuvax.nwu.edu!mailrus!cs.utexas.edu!asuvax!noao!arizona!coyote!jmh From: jmh@coyote.uucp (John Hughes) Newsgroups: comp.sys.tandy Subject: 16B Info/Tips/Resources (semi-long) Keywords: 16B, Xenix, Tandy Message-ID: <1990Sep12.073838.8635@coyote.uucp> Date: 12 Sep 90 07:38:38 GMT Reply-To: jmh@coyote.UUCP (John Hughes) Organization: Datalog Consulting, Tucson, AZ Lines: 241 Lately I've noticed some confusion floating around here about the Tandy 16B. So, manuals in hand, here is what I know, both from the books and my own experience (not to mention the kindly assistance of other 16B owners, to whom I am very grateful). 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. If you have easily answered questions, I'll be happy to look up what answers I can from the manuals for you on an 'as-I-have-the- time' basis. I also have available details on things like installing 5.25" disk drives, increasing available memory, and upgrading the processor clock speed. Send questions/suggestions/comments to: coyote.UUCP -or- arizona!coyote!jmh dev.null Thank you. ------------------------------------------------------------------ Referenced Publications: 1 - TRS-80 Model 16 Service Manual RS Catalog Number: 26-6004/5/6 2 - TRS-80 12/15 Meg Hard Disk Service Manual RS Catalog Number: 26-4152/3/5/6 3 - User's Handbook To The TRS-80 Model II 1983, Webster Systems, Inc.; Cleveland, Ohio 4 - TRS-80 15-Meg Hard Disk Owner's Manual RS Catalog Number: 26-4155 ------------------------------------------------------------------ What the Model 16 Is, and Is Not First off, the Model 16 is essentially an extended version of the Model II, with the primary difference being the inclusion of the 68000 CPU for the Xenix operating system. In fact, it is possible to upgrade a Model II to a Model 16 Xenix machine without too much pain or strain. The Model 16 retains the Model II's Z80 processor as an I/O handler. The Model II represented a departure from the Model I, both in it's software and hardware design philosophy. As reference 3 puts it: "The Model II is not an expanded version of the Model I. It is an entirely new computer." (p. 11) In addition to the much-beloved TRDOS (tongue firmly in cheek as I say that..), one could also run CP/M. Hence the 16B, with its direct ancestry to the Model II, is not a fancy Model I or Model III, and should not be mistaken for such. 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 External Hard Disk Unit - 12 and 15 Mbyte units ARCNET interface system Graphics Display Upgrade 3-port Serial Interface I have also heard mention of a cartridge tape subsystem. It shows up as a 'diskutil' menu selection, but I've never seen one. 16B Hard Drives To reasonably run a 16B with the Xenix OS, one needs at least a 12Mbyte hard drive, and that will be *tight*. It is not unusual to allocate between 2 and 4 Mbytes of drive 0 just for swap space. Then the /bin and /etc directories take up another chunk. If you don't plan on installing the development software (nice things like cc, lex, and yacc) then you might get by with 12 megs, but I doubt it. I would consider 15 megabytes to be a reasonable minimum hard disk size for any 16B system. 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. At the hard drive end, one will find either one of two cards: the 8x300 (old) or a Western Digital WD1000-TB1 (new). The difference is easy to spot, the 8x300 is big, and takes up most of the PCB shelf space in the external drive enclosure. The WD1000 is about half that size. 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?). Just to make things more confusing, there are two variations on the outboard hard drive units, primary and secondary types. A primary type contains the actual controller. The secondaries simply contain a power supply and a drive. Connectors on the backs of the cabinets allow you to easily connect everything (provided you have all the right cables). Another interesting thing about the primary- secondary system is that the primary will control the power supplies of the secondaries. As a result, when you twist the keyswitch on the primary, all secondaries connected to it will also spring to life. See references 2 and 4 for more details about this. Both controller card types expect to see standard ST506 MFM drives connected to them. As with any other ST506 installation, the drive control cable (the 34 pos. one) is daisy-chained from drive to drive. Each drive gets a dedicated 20 pos. data cable, each of which connects to one of the four 20-pin header connectors on the controller card. The cables are exactly the same as those used in your garden variety PC. If you already have a hard drive (and I'm assuming that you do), then it isn't too difficult to figure out where the next data cable should go. Additional hard drives are formatted and initialized for Xenix use with the 'diskutil' utility. Refer to your system operation manual for details, but it's really very simple to use. With no diskettes in the floppy drives a 16B system will attempt to boot from hd0 if it can find it. This is also where the swap area usually goes. 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. 16B Floppy Drives There has been some info circulating through the net about how one can replace the 8" drives with more reasonable 5.25" drives. I will be glad to mail this to you if you don't already have it. Many of the older 16B systems (if not all) used single-sided floppies. This translates to about 600K of storage per disk. The newer 6000 machines used double-sided diskettes. In fact, if you plan on installing the latest and last release of the Xenix development system, then you will probably need double-sided drives. I haven't seen any single-side distribution disks for this software. 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. 3-port serial I/O cards are available for the 16B and 6000 machines, and they run about $250 or so each. You can have up to 8 serial ports (the two standard ports plus two 3-port add-on cards). Other Considerations Memory size is a critical determinant in the overall speed and response of the 16B. A machine with less than 512K will spend most of its processing time just trying to get out of it's own way, and you'll get to hear a hard drive start to complain about excessive swapping. 512K is bearable, but 1 meg is a lot better. If you are handy with a soldering iron, you might consider modifying a stock memory card to handle 1Mb worth of RAM (I also have available the details on how this is done, if you're interested). I would suspect that one could also purchase additional cards. The speed of your swap device also affects the overall throughput of the system. Although the old Tandon drives are tough as hell, they are also slow. Installing a fast drive will greatly enhance your system. Finally, bear in mind that unless you have the latest and last release of the development software, you will not be able to do things like handle sources that use 32-character identifiers. Which means that a lot of newer Unix/Xenix sources will be out of your reach, unless you want to modify the code. Contacts Bob Snapp is well known to 16B/6000 machine owners. He offers a variety of services and hardware. Bob Snapp 6962 Plainfield Road Cincinnati, Ohio 45236 513 891 4496 compuserve 70225.155 Your local Radio Shack Computer Center can also special order manuals and perhaps some hardware and software for you. There are three public access/BBS systems that I'm aware of that either run on 16B/6000 machines or have software available for them. These are: eskimo 206 365 5458 (16B system) mundane 608 256 3133 (6000 system) sir-alan 814 337 3159 (used to be a 16B) If in doubt about 9600, log in at 8/n/1 2400 or 1200 bps. You will see a log-in prompt with instructions. Also, the number for sir- alan may not be valid after about the middle of September, since the log-in bulletins say that the system is moving. I'm sure a new number will be posted somewhere in the newsgroups. Suggested Reading Life With UNIX: a guide for everyone; Libes and Ressler 1989, Prentice-Hall, ISBN 0-13-536657-7 UNIX Internals; Shaw and Shaw 1987, Tab Books, ISBN 0-8306-2951-3 UNIX System Administration Handbook; Nemeth, Snyder, Seebass 1989, Prentice-Hall, ISBN 0-13-933441-6