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Model 12 BUS BOARD

H

Hans01

Experienced Member
Joined
Feb 17, 2014
Messages
459
Location
Netherlands
I have a Model 12 without a busboard for more than a year now.
I never succeeded in finding a card cage and bus board for this computer.
At last I decided to build one myself.

At first I found someone who sells the bus connectors as a start.
There was no schematic available of the board, but with studying
the Model II and Model 6000 schematics I found all I need for this job.

Asking Pascal to draw the gerbers, he was in for help and is drawing them now.

The project exists of a PCB with 3 bus slots and two flatcables with 40 wires each
to connect to the motherboard. The termination of the lines is done.

Here is a picture how it is going to look.

BUS-M12.jpg
The flatcables connects to K5 and K6 are to solder on the busconnector on the backside of the motherboard.
In this mode K1, K2, K3 follow the connector on the motherboard, the video card stays on his place.

There will be a second option, see this picture.
option.jpg
The leftside is the same as above, but the rightside has two connectors for the flatcables and a 80 bus edge connector,
just like the one on the hans-02.

You can mount the leftside anywhere you like and the connector on the rightside in the busconnector on the motherboard.
The motherboard connector is now copied to C1. The videocard is inserted in C1 now.
No need to solder on the motherboard.

How far is the project.

The gerbers for the leftside are nearly ready and can be tested.
The rightside must be drawn (but is a stripped hans-02).

If you are intrested in this project, please let me know.
If you have any suggestions, please do.
 
Last edited:
@Han01 keeps on producing awesome hacks! Nice work!

I too have pondered this idea as the Model 12 without a card cage is a neutered beast.

One strong suggestion is to add more bus connectors. With only 3 slots available and with 1 taken by the video card, you can't have 68000 OS (e.g. Xenix) with a HD.
 
I like it. With the extra bus connector you can add a Model II HRG board and that is all I'd need because I don't use the 68000 functionality of my 8in TRS-80s

Ian.
 
@Ian and @pski

I have limited the number of slots for two reasons.
My first plan was to use it for the hans-02. The second was the costs of the PCB, which increase dramaticly above a certain size.
I'll ask Pascal if it is possible to increase the number of slots.

Ian, in that case you MUST move the video board to the bus. It is not tested but it seems possible to me.
 
So are there two 40pin busses on the M12 motherboard which the Hans-03 connects to? That gives a total of 4 slots (including the one on the M12 motherboard).

You could theoretically add two long(ish) IDE cables and sit the Hans-03 outside of the case at the back or on top of the Model 12...

Ian.
 
TRS-Ian said:
So are there two 40pin busses on the M12 motherboard which the Hans-03 connects to? That gives a total of 4 slots (including the one on the M12 motherboard).
Ian.
Click to expand...

I think what Hans is proposing in option 1 is that you solder the (2) 40pin cables to the backside of the 80 pin slot on the main logic board. Option 2 is much more preferable as you don't need to modify (or remove) the main board. Hans please correct me if I am mistaken.

You could theoretically add two long(ish) IDE cables and sit the Hans-03 outside of the case at the back or on top of the Model 12...
Click to expand...

There is so much empty space in the M12 that I'd have to find a way of keeping the cards in the case.
 
@pski

Option 1 gives you a total of 4 slots, but you need one for the videocard.
Option 2 gives you a total of 3 slots (The slot on the motherboard is used to connect the exra bus)
The videoboard moves to the first slot on the extra bus.

There is so much room in a Model 12 to mount the extra bus, this seems no problem to me.
 
Just to show you the progress and give an idea about how it looks.
Here some pictures of the Model II family bus extender.

I hope to receive the last parts this week and then can test the board.

HPIM0267.jpg HPIM0268.jpg HPIM0269.jpg
 
I guess I could not sell you on adding more slots? :)

I'm eagerly awaiting your testing results with different cards.

BTW, something like this would be awesome for the Model I too, so that you can use more than one expansion device. I know I would be interested in that.

e.g. http://www.trs-80.org/expandabus/
 
@all

Some extra info about my Model II bus extender.
In the poll about Model II owners there were 16 responders :(. Let we add another 16 for
the guys who didn't respond, has more than one or has an other member of the Model II
family.
If I see the response on the PM's on my request for the hans-01, I must conclude that there is a very small
group of users who want to improve their MII :(.
That is one of the reasons why I had to set the number of slots to three. If you see how much the costs are
sofar, you can see that higher costs would decrease the number of users. (sorry for you Pete)

I would show you some extra options with the hans-04 (this new bus extender)
If you build the the 2 boards and leave all the termination and pull-up resitors and connect the two boards
with flatcables of about 40 cm. you can use the board to test or repair any other board in circuit.
It is very easy to read signals or do mesurements.

If you only use the busconnector part with two flatcables, you can monitor bus signals and levels in a very easy way.

If you use the busconnector part you can easy connect devices to the bus.

One serious warning.

Pay attention to the orientation of the boards, check if all pin 1 positions are connected to each other.
Pay attention to insert new boards in the right way in the new bus, take a look at the arrows.
Connecting in the wrong way would surely damage the busconnector and most likely your computer !!

You are warned !!!!
 
I guess I'm one of the other 16, I've been hanging back as I won't have time to work on this right away. I own 2 model 12 computers that are in working order, so I'm definitely interested in 1 or 2 of these. As a precaution I have ordered the bus connectors so I will be ready when time permits.

Kipp
 
Hello Hans

I have a Model II with the usual cards: floppy, CPU, memory, video. There are slots free I think, but where to get the additional cards from? You never see them for sale for less than silly money. And one of those slots is about to get a Hans01 fitted :)

I'm not sure I can use the additional space in a model II - a 16 is different I guess...
 
@JonB

There are a lot of low cost Model 12, they don't have a cardcage nor a busboard at all.
The FDC, I/O and Memory boards are integrated in the Motherboard.
There is one busslot on the motherboard and that is used for the videoboard.
These Model 12's cannot expanded and are very useless.
With the hans-04 you can use them as a Model 12 with expansion bus.
On the other hand you can use the hans-04 to easy repair bus boards.
Read about this in some postings above.

There were a lot of cheap Model II boards on Ebay, like Hi-Res graphics, Memory, 68000, FDC, Harddisk, hans-01, etc.

So if you have some hardware knowledge you can modify your excisting Model II family computers to a powerfull beast.
 
I have an idea, I don't think it's too radical... since the hard work has been done on the 3 slot busboard, it seems to me that the extra work to add three more slots in the CAD software would be relatively straightforward, which then generates the necessary gerber files for those who need more than three slots.

Yes, it would be rather more expensive than the 3-slot version but for those who want one would probably be happy to pay the extra.

I'll run it by Hans and P.H and see what they think.

Cheers,

Ian.
 
TRS-Ian said:
I have an idea, I don't think it's too radical... since the hard work has been done on the 3 slot busboard, it seems to me that the extra work to add three more slots in the CAD software would be relatively straightforward, which then generates the necessary gerber files for those who need more than three slots.

Yes, it would be rather more expensive than the 3-slot version but for those who want one would probably be happy to pay the extra.

I'll run it by Hans and P.H and see what they think.

Cheers,

Ian.
Click to expand...

+1 You know I fully support this as it will allow a Model 12 to truly become a 16B/6000 compatible machine.
 
Google translation
Yes I can make the change, but it is hard work !!!!
If I have no problem: Two days (16 hours)
If I have many problems (I have to change resistor networks): a work week ( 40 hours).
For example, draw the "Hans01" connector in my library represent two working days. Draw the "HANS03" a day !!!
I do this for free for fun, for exchange, as a hobby !!!
but why draw for model II, 12, 16 etc ...
I do not own these machines !!!

Draw Grafyx 3.2 cards; 4.2; 5.1 or Tandy 26-1125 and 26-1126 brings me more in my collection.

But when I asked for information on card except some people. I have no answers !!!! For example the card "Newclok-80 M1",I waited one year for the photos !!!!

So I can make these changes. But I expect in return for information and assistance for my collection


I have drawn you with cards free for fun. In return you still want more !!!! When I asked for information, you do not answer

For Hans and Ian, I will make those changes.
But every change wonder a work day. that I can't use for my collection

The automatic "CAD" do not exist except on advertisements

P.H.
http://www.prof-80.fr/
http://www.prof-80.fr/trs-80-modele-ii

Recherche

Je suis à la recherche de ces machines et cartes:
LNW-80
TRS-80 modèle II
"Le Guépard" H B N COMPUTEUR
Cartes Orchestra 85
Cartes speed
Carte clock
Carte CP/m
...etc


Traduction Google
Oui je peux faire la modification, mais elle demande beaucoup de travail!!!!
Si je n'ai pas de problème: deux jours de travail (16 heures)
Si j'ai des problèmes (je dois changer les réseaux de résistances): une semaine de travail (40 heures).
Pour exemple dessiner le connecteur "Hans01" dans ma bibliothèque a représenté deux journées de travail et pour "HANS03" une journée!!!
Je fais cela gratuitement pour le plaisir, pour échanger, comme hobby!!!

mais pourquoi dessiner pour le modèle II, 12, 16 ...etc
Je ne possède pas ces machines!!!
Dessiner les cartes Grafyx 3.2; 4,2; 5.1 ou Tandy 26-1125 et 26-1126, c'est un plus dans ma collection.

Mais lorsque je demande des informations sur des cartes, excepté certaines personnes. Je n'ai pas de réponses!!!! Pour exemple la carte "Newclok-80 M1" j'ai attendu une année des photos!!!!
Donc je peux faire ces modifications. Mais j'attends en retour des informations et de l'aide pour ma collection

Je vous ai dessiné des cartes gratuitement pour le plaisir. En retour vous voulez toujours plus!!!! Lorsque je demande des informations, vous ne répondez pas

Pour Hans et Ian, je vais faire ces modifications. Mais chaque modifications me demande une journée de travail que je ne peux pas utiliser pour ma collection
Les "CAO" automatiques n'existent pas excepté sur les publicités
 
P.H, you always have the option to say no... I'm not enough of an engineer to speculate on how much time these things take and no one really minds if you take some time out to work on your other projects that are more interesting to you.

Let's just leave it at 3 slots for the time being and see how many people go for it.

Also some of this old aftermarket hardware is very difficult to find and we do our best to bring it to your attention when we find it.

I know it's been a busy year but by all means only do what you enjoy doing.

Ian.
 
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