How do I boot a Model 4 from disk?
Blake Patterson
I've been into computers since '82). How do I boot it from disk?
I have TRSDOS 6, LDOS, etc. But I turn the machine on and am greeted
by "CASS?" and then a request for sys memory levels and then a
prompt. The two drives are spinning at this point. How do I boot the
DOS?
Thanks!
bp
Tom Lake
"Blake Patterson" <blak...@gmail.com> wrote in message
news:19008afd-f196-4da2...@z72g2000hsb.googlegroups.com...
If you're getting the CASS? message without holding down the Break key,
either the disk drive interface is defective or the Break key is stuck down
somehow. A working Model 4 should display a Diskette? message if the
Break key isn't held down.
Tom Lake
Blake Patterson
> "Blake Patterson" <blakes...@gmail.com> wrote in messagenews:19008afd-f196-4da2...@z72g2000hsb.googlegroups.com...
And is it normal for a Model 4 to say, at start:
Radio Shack Model III Basic
(C) '80 Tandy
??? Tnx.
bp
Blake Patterson
Several keys are bad: 2 r j ; z v b ...BREAK seems to work tho - it
CR's when I hit it.
So is the disk system dead? Steps to diagnose? Oy... Tnx. :-(
bp
Bill Plenge
Sounds like your problem is caused by the keyboard issue. The Model 4 would
boot to Model III cassette mode if a certain key was held down at power on.
That's why you were getting the Model III message. I don't remember what
key it was, it's been a long time. It sounds as if once the keyboard issue
is resolved it should fix your booting to disk problem too.
Best,
Bill
Blake Patterson
I see dated photos of this unit on the eBay auction item listing.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260230790905
It would seem something in shipping caused this to happen - certain
keys to die and perhaps something sticking preventing booting in
normal disk-based mode. I wonder what it could be? Opening up the
unit worth anything here? Thanks...
bp
Knut Roll-Lund
Combinations of stuck keys might be seen as other keys but then that key
would not work so if you get a response from pressing break it is
probably ok.
If it falls directly into basic then it doesn't see the
floppycontroller, thinking it is not present (assuming break is ok, not
stuck).
?INP(240)
This reads the floppycontroller status. Without '2' key you can't do
this but you have also a '2' key in the keypad... so I hope you can use
that. My machine reports 128 regardless if there is a disk in drive :0
or not, going directly to basic by holding down break key. My machine works.
Does the access light up on drive :0 too? This is drive select and is
necessary for the drive to be seen.
OUT244,1
Should make the access light on drive :0 light up and spin the drives
for a short while.
Probably reseating the ic's on the disk controller could help too. The
connector between the disk interface and the mainboard could also give
bad contact but when reseating that you need to be extremely careful (it
is likely to fall apart).
It is likely you have to open the machine. Caution should be exacted
here too so you don't damage the CRT.
Here is a link to page explaining how I cleaned my model 4's keys (where
several didn't work - now they work well).
http://home.online.no/~kr-lund/repair.htm
--
Knut
(delete 'nogarbage.' for email)
Christopher Noyes
You could try unplugging the keyboard from the system board to see if
it boots from disk then(connects to the right side of the system board
when the front of the unit is facing you).
-CN
Blake Patterson
wrote:
>
> If it falls directly into basic then it doesn't see the
> floppycontroller, thinking it is not present (assuming break is ok, not
> stuck).
>
> ?INP(240)
>
I get a 255 out of that command. Is that telling?
>...
>
> Does the access light up on drive :0 too? This is drive select and is
> necessary for the drive to be seen.
>
> OUT244,1
>
Nothing happens and I get a "READY". Drives 0 and 1 are spinning
constantly, though I've never seen the drive lights on.
Is there a page explaining how to open this machine and giving other
info I might want to see regarding the disk controller, etc.?
Thanks...
> ...
>
> Here is a link to page explaining how I cleaned my model 4's keys (where
> several didn't work - now they work well).http://home.online.no/~kr-lund/repair.htm
>
Thanks.
bp
Frank Durda IV
: I just received a TRS-80 Model 4 from eBay. My first TRS-80 ever (and
If the unit has drives and it says "Cass?" without you doing anything,
something has likely come loose or the BREAK key is stuck down.
Normally "Cass?" is only displayed if you explicitly ask for ROM
BASIC by pressing BREAK while also pressing the RESET (orange) button,
or if the boot ROM doesn't see the disk controller.
During a normal boot from media you press no keys other than the
RESET button. (You do press keys on the Model 4P depending on what
is to be done.)
As you do appear to have drives, I would initially check the flat
cable between the processor board (big one) and the floppy disk
controller and make sure it is plugged in straight on both ends.
That is a fragile cable that is very difficult to replace, so be
careful with it. I'd also check the floppy disk controller power
cable and make sure it is plugged in on both ends (FDC board and
power supply).
If the drives continue to spin after ten or more seconds in ROM
BASIC (at or after the "Cass?" prompt), this suggests the floppy
data cable is installed upside down, but that is unlikely if it is
the stock drives and cable, as the cable wouldn't be long enough to
install incorrectly. The runner-up possibility is that the disk
controller isn't getting power or the cable between it and the
processor board has issues. You could also have some chips that are
not well-seated in their sockets and need to be pushed back into
position.
Depending on the ROM revision, Model 4s with a disk controller may
display absolutely nothing when you turn them on, or they may
immediately (as soon as the CRT warms up) display "Diskette?", or they
may display that after several seconds. These are the four outcomes
of the major releases (there were over two dozen Model III and 4 ROM
releases including the non-US and educational model releases, and
some of those are very different.
1. Nothing displayed at all and drives may spin until you press
BREAK or insert bootable media.
2. "Cass?" is displayed immediately if you don't have a disk
controller or pressed BREAK.
3. "Diskette?" displayed until you insert media - drives may
never stop spinning until bootable media is inserted. If they
do stop, pressing any a key starts drives and it looks for
media again. A few versions required the key that is pressed
to be the RESET button.
4. Nothing is displayed for about six seconds while drives spin,
then drives stop and "Diskette?" is displayed. Pressing a key
repeats the cycle.
The versions where the drives never stopped was changed after complaints
that it conflicted with use diskette use policy, but mainly because it
wore the drives out, particularly in store demonstrator units. There
was no recall.
The terseness of the messages can be blamed on a tight ROM budget
and some really inefficient pieces of code in the ROM that left little
room for more informative messages. (On the 4P I argued and finally got
4K of ROM to be used in the machine - instead of the 2K that the hardware
group had originally planned - so I was able to provide more error
messages in the code, but even those had to be packed.)
The advised boot procedure on the "Model %s" models is to turn the
computer on, and wait for the disk drive to stop spinning or at least
the select light to go out (except on the versions where drive 0 never
stopped and never turned out the light), insert the media in drive 0
and press the RESET button (orange key).
In general you should never power on or power off one of these systems
with media in the drive. The risk of the drive burping out a brief
magnetic field as the head electronics powered down or up was pretty
high on old drives that could zap the data at the spot that the head
was resting over, regardless of the presence of the write-protect tab.
Tandon and TPI drives were particularly bad about doing this.
Also, remember that on the Model III/4/4D, the bottom drive is
drive 0, so that is where your single-sided double-density bootable
media should go.
Finally, check to see if your machine has Network 4 installed,
which would appear as two wing nut screws and an option switch
block protruding out through the metal plate where the power cord
comes out. I have heard that some Network 4 systems were sold with no
RS-232 board, which makes sense as the software environment would
have made RS-232 use difficult. Student stations would have had no floppy
drives either, but the instructor station would have had floppies and
network 4 hardware.
Oh, and you can find RS-232 pin-out details here:
http://nemesis.lonestar.org/reference/telecom/modems/dtedce.html
Frank Durda IV - send mail to this address and remove the "LOSE":
<uhclemLOSE.jun08%nemesis.lonestar.org> http://nemesis.lonestar.org
"The Internet has gone [ 0 ] days without an accident caused by an
insecure or buggy piece of Microsoft software." - Sign on the OSHA
bulletin board.
Copyright 2008, ask before reprinting.
Knut Roll-Lund
> On Apr 27, 7:35 am, Knut Roll-Lund <kr-l...@nogarbage.online.no>
> wrote:
>
>>If it falls directly into basic then it doesn't see the
>>floppycontroller, thinking it is not present (assuming break is ok, not
>>stuck).
>>
>>?INP(240)
>>
>
> I get a 255 out of that command. Is that telling?
>
Probably what you get when there is no response. It is what I get when I
INP a port that is not used. Possibly there is a contact problem
(reseating) or as drive spinning suggests the disk controller isn't
getting power.
>>...
>>
>>Does the access light up on drive :0 too? This is drive select and is
>>necessary for the drive to be seen.
>>
>>OUT244,1
>>
>
> Nothing happens and I get a "READY". Drives 0 and 1 are spinning
> constantly, though I've never seen the drive lights on.
>
> Is there a page explaining how to open this machine and giving other
> info I might want to see regarding the disk controller, etc.?
>
> Thanks...
>
The drives then consider the motor signal to be active all the time but
not the drive select... kind of strange. And no reaction to the OUT...
suggests the problem is more than just a loose floppycontroller. Might
be the interface isn't getting power.
There used to be a description though I couldn't find any now... :-(
There is a description in the technical manual.
Basically undo the 10 screws in the bottom without letting it come
apart. Place it the normal way, leave room on the left side (for the top
on its side). Then lift the top straight up and when it is free put it
down on its side next to the machine (left side seen from the front).
The leads for the video are long enough to do this. I like to be behind
the machine when I lift the top so I can look down the ventilation
openings to see that everything is ok. The trick is to avoid snagging
the end of the CRT tube on anything. I have done this many times now
without any problems but it isn't something I like to do.
With the top like this you can also test the machine. The monochrome
screen will not be affected by being on its side. Just remember that you
have mains power exposed if you power it up like this...
>>...
>>
>>Here is a link to page explaining how I cleaned my model 4's keys (where
>>several didn't work - now they work well).http://home.online.no/~kr-lund/repair.htm
>>
>
> Thanks.
>
> bp
>
JT SoCal
lifting, not removing, socketed ic's then gently pressing them back into
position. One of the additional problems that appeared from time to
time was oxidation on a connector or in a socket. This would cause
erratic operation at times. The model I keyboard to EI was particularly
problematic this way due to the gold plated edge card connectors meeting
with the solder plated PCB fingers. This appeared to be a random &
unpredictable problem when these machines were in frequent use & there
is no reason to think it has become better over the decades.
BTW when you get it working you might look around for a pair of
Mitsubishi double sided 80 track drives. They worked particularly well
and provided a great deal more storage capacity. I still have them in
my original Mdl I and a MDL III/IV and they still work. TRS-DOS 6/LDOS
& the Mdl III LDOS 5.x OS's, among others, work well with them. NewDOS
80 had to be told where the directory was and what the configuration of
the disk was in order to find it but the others worked directly. Of
course unless you use a double-step routine you will not be able to read
the 40 track media on the 80 track drive.
For the switch there was also a version that had a small plunger that
pushed a movable metal contact against the stationary one. The assembly
was very similar to the one in the picture but it did not have the
conductive rubber membrane, it had a tendency to develop a film on the
surface, over time, that would increase the contact resistance until a
failure. Cleaning would generally bring it back into operation. The
metal contact version was much more reliable. Some also had 4 solder
points while others had just 2. If you do try the repair path get a
length of sold-wick material or a solder sucking tool to clean the
solder out of the hole before trying to remove the switch. There are
still some local, small, electronic stores where these can be obtained.
If you have not used these before get an old trashed board of some
kind and practice a bit first before going after your good board. To
much heat will damage the through hole plating and possibly lift the
circuit material off the board surface causing more repair to be needed.
Good luck with it. Anything can be repaired it is just a question of
how much time, and energy, we want to devote to the effort.
JamesSoCal
Blake Patterson
http://www.flickr.com/photos/blakespot/2446770698/in/set-72157604743399188/
:-) I guess I should do the desolder and clean key drill to get the 7
or so dead keys working again. I assume no way keyboard cable seating
could cause that problem? (Looks solid, have not reconnected tho.)
bp
Michael Black
> Sounds like your problem is caused by the keyboard issue. The Model 4 would
> boot to Model III cassette mode if a certain key was held down at power on.
> That's why you were getting the Model III message. I don't remember what
> key it was, it's been a long time. It sounds as if once the keyboard issue
> is resolved it should fix your booting to disk problem too.
>
keyboard decode, then a bad key in the same row or column would be seen
as the "break" key and nothing can happen. I don't know if this is the
case here, or even if the "break" key is part of the keyboard matrix,
but I'm sure that sort of thing was done at times. In this case, all
they'd want is something to indicate that the user does not want to boot
from the floppy drive, so there's no good reason why they'd be pressing
some other key than "break".
I remember one example of this. When the Color Computer III came out,
there was that photo in the ROM that could be displayed with a certain
key combination. Rainbow magazine had a contest to come up with other
ways of displaying it, I figured out what was going on and presented
a big of code (and won a prize) but most of the other winning entries
were about other key combinations. That wouldn't have worked except
that only partial decoding had been done.
Michael