Nf-ID: #R:mnemosyne.cs.du.edu:26659:nemesis:-31017:000:8248
Nf-From: nemesis.UUCP!uhclem    Apr  7 21:14:00 1992


<>
[0]There seems to be an enormous variety of problems getting 4.? versions
[0]of TRSDOS to boot up on these machines.  The system hangs up half way
[0]through.

There were 10 different versions of TRSDOS 4.2.x:  4.2.0 to 4.2.9.  I'll
explain one of the reasons why in a second.

[0]For example:
[0]
[0]1.  If you install a harddrive board in a Model 12, no version of 4.?
[0]	TRSDOS will boot.  I installed a harddrive board that came out of a
[0]	Model 16 into a Model 12.  I can run XENIX with no problem but forget
[0]	TRSDOS 4.?.  The problem goes away when the harddrive board is
[0]	removed.

The problem is there are two basic types of controllers for the Models
II/12/16/16B/6000 systems.  These come on three different types of controller
board.  Version A uses an 8x300 CPU (the large purple chip) that appears
in the external primary drive cabinet.  This controller was used in the
8Meg drives initially.  When the 5 & 12 Meg drives became available, a
different version of the 8x300 controller was used.  This change required
a different host interface board in the computer, and prevented 8Meg owners
from using 5 & 12 Meg drives and vice versa.  This change was transparent
to software and the 8x300 controllers were used with TRSDOS 4.0, 4.1 and
4.2.  4.2 versions supported sizes other than 8Meg.

After that point, the 8x300 design was replaced with the 1010 controller.
(Version B.  The 8x300 was emulating in software what the 1010 would do
when it became available.)  The 1010 came in two different boards.  One
board went in the external primary drive case in place of the 8x300 board.
The other went in place of the host interface board in the computer, but
only allowed two drives to be connected.

The problem was that the 1010 was not entirely compatible with the 8x300.
The way you read status after a drive error was different, some new values
had to be programmed when formatting,  restores took much longer, etc. 
So a modified version of TRSDOS 4.2 was created to support the 1010
controller.  At the same time, the boot ROM was modified to work better with
the 1010, and to delay longer for the larger drives that were taking quite
a while to get back to track 0.

(The differences in hard disk controllers is discussed further in an
 article I wrote some time back on hard disk systems.  Look for
 6000>4000>3000 Vol 1, No 2. for more information on controllers.)

The problem with TRSDOS 4.2 was that they were unable to make a version
that supported both 8x300 AND 1010 controllers, so you had to have the
the right version (or versions) for the disk controller you have.  One
won't work right with the other.

[0]2.  On 16B/6000 HD machines only TRSDOS 4.2 will boot and 4.1 will not.
[0]	This is not helpful to those that own a ton of software written
[0]	under 4.1.

This clearly indicates that you have an 8x300 controller on your system,
since TRSDOS 4.1 boots.  You therefore need the right version of
TRSDOS 4.2.x to use with your 8x300 controller.   TRSDOS 4.2.5 and
TRSDOS 4.2.6 were the longest-lasting versions.  The difference
between these two is 8x300 or 1010 support.  I used to have a lovely
tree-chart that showed the the various TRSDOS 4.2.x versions (created it
to explain it to Radio Shack marketing!), but I can't find it now that
I need it again.  At a guess I would say you need TRSDOS 4.2.6.  I
recall always booting TRSDOS 4.2.5 and I had a 1010 controller.

As far as the rest of the operating system is concerned, any Z80-based
software from TRSDOS 4.1 will run on 4.2.x.  TRSDOS-16 *might* also
work, but it was deleted from the disks by 4.2.5/4.2.6, and was no longer
supported, and the hooks may not be there anymore.

If you can find it, TRSDOS 4.4 should work with both controller types.

By the way, Model 16 XENIX had to be re-released because of the disk
controller change too.  This happened back in the 1.x.x days.


[0]3.  Model 16 machines have several problems:  Some Model 16's simply will
[0]	not run TRSDOS 4.? versions at all and others have no problems. 

A repeat of the same question above.  Some Model 16's probably have
different hard disk controllers and are running the correct versions of
TRSDOS 4.x for that hardware.

[0]Further, the serial card on a Model 16 appears to differ slightly
[0]with other 16's causing XENIX not to boot up from the harddrive. 
[0]Apparently, the chips are slightly different.  I noticed this recently when
[0]I switched cards between 2 machines and my XENIX formatted external
[0]harddrive would not boot up.

This makes no sense.  Why would the serial card (I assume you are talking
about the 3 port card) affect the systems ability to boot?  TRSDOS 2.x
and 4.x doesn't know anything about the three port card, and the two built-in
SIO serial ports (on CPU board) are absolutely 100% identical across the
Model II/12/16/6000 line. 

More likely, you are talking about the Model 16 CPU board, which happens
to have the two serial ports on it.  When you swapped it, you also changed
the boot ROM, since it is on that board.  The ROM has to match the disk
controller you have.  As a Model 16, it was probably shipped with the 8x300
controller code in it.


[0]4.  TRSDOS 2.? versions boot just fine on all machines with no
[0]	problems at all.

TRSDOS 2.0 ignores the hard disks entirely, and therefore can't get stuck if
the "wrong" one is connected.  There are two versions of TRSDOS 2.0 to
worry with:  TRSDOS 2.0a and TRSDOS 2.0b.   "b" should be used with
half-height drives.  "a" was for the older full-height drives you find
in Model II and Model II disk drive bays.

[0]Now it seems to be that the various cards on these
[0]machines including the floppy drives have to be jumpered with clips
[0]to accomodate the various configurations.  Many of the boards have
[0]posts protruding from them that will accomodate jumper clips.
[0]My question is how to solve these problems.  Do I need to jumper
[0]boards located directly on the floppy drives differently, or other
[0]boards as well. 
[0]If so, can someone provide me with the numbered locations on each
[0]board that need jumper clipped.   I need to solve the problem of
[0]why TRSDOS 4.? will not boot.

Yes, there are numerous configuration jumpers on all the Model 16 boards that
do various things.  But fixing your hard disk-TRSDOS 4.2.x problem
can't be done with a jumper.  You need the right ROM and operating system.


[0]It seems that this family of machines has a maddening variety of
[0]modifications even between the same Models that just causes more
[0]frustration to those like me who often move parts around to keep the
[0]machines running, and that want to be able to run all of the software
[0]versions.

That is the penalty we all pay with rapidly changing technology.  Try sticking
a IBM PC memory card into a IBM AT.  Or a 6MHZ IBM AT Extended memory card
into the 8MHz version.  Depsite the fact that all systems are 100% IBM
compatible, the changes in the system make the use of these cards impossible
or unreliable.  Don't you think those people who bought those $2500 8 Meg
hard disk systems were upset when they found out they had to stick with
all 8 Meg systems or dump them and get the new 12, 15, 30 and 70 meg drives?

By the way, when you swap controllers, the drives attached should be
reformatted.  So if you move a secondary drive to a different primary,
or if you swap boards in the primary, you need to reformat for reliable
operation.  This holds true on the IBM MFM controllers too (also 1010/2010).

The Model II/12/16/16B/6000 line actually has very few incompatibilities
like this across the line.  This change in hard disk controller/operating
system incompatibility just happened to bite you and the fix was not
obvious.

And finally, on the net if you ask for info or help, a name and address
to reply to is considered proper.  The last half-dozen postings of yours
have had no name or address included.   Thanks for the cooperation in future.

Frank Durda IV <uhclem@nemesis.lonestar.org>|"The Knights who say "LETNi"
...utacfd!nemesis!uhclem (nearest internet) | demand...  A SEGMENT REGISTER!!!"
...letni!rwsys!nemesis!uhclem	            |"A what?"
...decvax!microsoft!trsvax!nemesis!uhclem   |"LETNi! LETNi! LETNi!"  - 1983