I have asked the Raspberry Pi community to help me with the construction of a 
DVI-like video-output device. I made the assumption that the DVI was only a 
terminal. Both from the response here, as there, I understand now that this 
combination is far more 'intimate' than I presumed.


I hope that the response given in the above thread helps and incites people, 
with far better and more knowledge of the processes and controllers involved, 
to pick up on this project and propose the parameters for a video-interface.

As far as I understand, the driver loaded from the DVI re-maps the video 
controller of the M100 towards the one in the DVI, where new tekst and graphics 
are generated. The 4K memory in the schematics is obviously the video-RAM, 
where 40x16 text (640 bytes) and 240x128 points  (3840 bytes) reside. I suppose 
text and graphics do not reside in different memory locations. (because it 
doesn't fit...)

Anyway, contrary to what I thought before, we will probably need to activate 
the SCREEN 1, 1 directive with software on the M100 itself. But that software 
does not need to be as big as the original driver, because no disk-routines are 

I'm sorry if I sound presumptuous, and I apologise if I impose on people's 
limited time, but I think this is a project worth pursuing.

(And I still didn't get an answer about the experiment I proposed, below.)
Greetings from the TyRannoSaurus
Jan-80             """""
@ work            ( @ @ )
Sent: vrijdag 9 februari 2018 09:47
To: 'm...@bitchin100.com'
Subject: RE: [M100] List of wanna haves

.. .. (As I'm accessing this list from 2 different locations,
.. .. and my yahoo-postings aren't always visible to everyone,
.. .. I have repeated the question I send below)

I'm sadly enough not that technical, so I can't draw the same conclusion from 
the link below. Can't that be confirmed from the ROM BASIC dis-assembly too? 
Without a DVI connected and drivers loaded, what does SCREEN 1,1 do ?

Anyway, even if it is wrong: would it take a lot of effort to re-write only the 
display output portion of the DVI-drivers? That way, development could start on 
a software solution for the video-output via the system bus. I had thought of 
using the GPIO-pins of a Raspberry Pi for that. As the R.Pi can also emulate a 
TPDD, you'd have a virtual DVI replacement, there.
Greetings from the TyRannoSaurus
Jan-80             """""
@ work            ( @ @ )
From: M100 [mailto:m100-boun...@lists.bitchin100.com] On Behalf Of Brian White
Sent: vrijdag 9 februari 2018 01:59
To: m...@bitchin100.com<mailto:m...@bitchin100.com>
Subject: Re: [M100] List of wanna haves

That won't work. I don't remember where I read this, but I read that the system 
rom has calls for certain functions but they are just stubs. The rom only 
contains the stub of a call that says "open CRT: for writing" which just says 
go to some address and do whatever that address says. Normally that address 
just points to the address for the built-in routine to return the FC? error. 
But if dvi dos is installed then that address contains the address of the 
routine in dvi dos to actually do something.
Aha, here's where I read it. Start on page 257
I can try it when I get home but we already know.


From: Jan Vanden Bossche [mailto:jan80...@yahoo.com]
> how would you use it?

To have a bigger screen to work on, when not on the move. Imagine, a 17-inch 
old VGA monitor with 40 x 24 characters! HUUUUUGE!

I have a question, for anybody having a DVI:
Could you try the following: is it possible to operate a Model T hooked up to a 
DVI, with the DVI ready to accept input and disk commands, but the Model T 
without the driver software? I would think this is possible when you boot up 
both machines, establish the connection, and then, while connected, reset the 
Model so that it is no longer aware of it's 'companion'. At that moment, enter 
BASIC and type SCREEN 1,1. That would send all BASIC output to the DVI, right? 
Does it ? (thàt's the question)

The above experiment would show if it's at all possible to run a monitor-only 
part of a DVI, without loading software on the Model T to do so. I hope, that 
the simple command SCREEN 1,1 does send some screen-positioning code through 
the bus towards the DVI, even without the drivers loaded on the Model T.  If it 
does, some clever programming on the receiving side could just give us the 
DVI/video-only device we seek.

Greetings from the TyRannoSaurus

From: Mike Stein <mhs.st...@gmail.com<mailto:mhs.st...@gmail.com>>
To: m...@bitchin100.com<mailto:m...@bitchin100.com>
Sent: Thursday, 8 February 2018, 3:49
Subject: Re: [M100] List of wanna haves

Just curious: how would you use it?


----- Original Message -----
From: "Randy Kindig" <randall.kin...@gmail.com<mailto:randall.kin...@gmail.com>>

> Agreed!  Just the video part of the DVI would be high on my list

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