Hey Philip/Steve,

I can't say about most, but SR is not DVI compatible. Executing SR from SCREEN 
1 seems to trash the display, but not hang the  ROM. You can F8 out to MENU. I 
would say then that the LUCID and WRITE ROMs would act the same. As for DISK+ I 
can't say, but would certainly like to know.

As of late, I haven't tried with REXCPM, but have tried SR under DVI with REX 
and that was not pretty. It ended up in a hard reset and loss of test data. As 
I recall, I could recover w/ TS-DOS active under REX and DVI, but I in any case 
option ROMs and DVI seem to be a void that never was crossed and why I didn't 
pickup my original DVI until I found one hidden in a RadioShack for $99.

These "test" were before the latest REX updates (43). I'm off this week so 
should have some time to check it out again, but I must first finish a keyboard 
drawer for a media table I'm setting up as an M100 work station and assemble my 
MVT100.

God Bless,

GregS <><

Dec 27, 2020 6:10:49 AM Stephen Adolph <[email protected]>:

> Hi Philip,
> 
> I really don't know what option ROMs work with the DVI.  Good question. Does 
> anyone know?
> 
> I'm not thinking seriously about trying to modify option ROMs to make them 
> DVI compatible.
> My test bed is real hardware and VirtualT, which can drive MVT100 using COM1.
> 
> cheers
> Steve
> 
> On Sun, Dec 27, 2020 at 2:09 AM Philip Avery <[email protected]> wrote:
>> Good going with this, Steve. Are you debugging all this on real hardware or 
>> have you hacked VT to do 80x24, ie emulate MVT100?
>> 
>> Also, does MVT100 work with all the OptROMS that work with a DVI? Or are you 
>> attempting to do more OptROMS?
>> 
>> Your interrupt dilemma... sounds like an early REX function would be useful 
>> here. Swap out the the System ROM when activating VT100 to a hacked System 
>> ROM with VT100-friendly interrupt routines.
>> 
>> Philip
>> 
>> On 27/12/2020 1:21 pm, Stephen Adolph wrote:
>>> My deep dive on VT100 driver integration into REX has been tiresome but 
>>> interesting.  Many bumps on the road, and learnings.  Actually pretty 
>>> painful to be honest.
>>> 
>>> I have been able to explore a few ROMs, and figure out if they work or 
>>> don't work with "VT100".  (which really is a modified "Disk Basic" from 
>>> Microsoft, and derives from the work others have done to disassemble Disk 
>>> Basic).
>>> 
>>> Interestingly, ROM2 Cleuseau seems to work very well with VT100!. Should 
>>> not be a surprise as it seems to use the LCD in a simple way.
>>> 
>>> TS-DOS ***almost*** works.  You can imagine that with a few tweaks it could 
>>> work on an 80x24 screen, but  then again, perhaps not usefully.  "just look 
>>> at the small screen!"
>>> 
>>> Haven't tried any other ROMs yet.  An 80x24 spreadsheet  and word processor 
>>> would be great!  Time to try Super ROM.
>>> 
>>> Anyhow, with a bit of knowledge gained, it seems like it might just be 
>>> possible to modify ROM programs to use 80x24.  Especially if they use the 
>>> "stock calls" for printing to the screen. 
>>> 
>>> I have implemented an "expert mode" and a "safe mode".  The safe mode 
>>> renders option ROMs unusable in REX, whereas the "expert mode" means ..have 
>>> at it.    So, if you wanted to use R2C100 on an 80x24 screen, switch to 
>>> expert mode and off you go.
>>> 
>>> The most painful learning for me is just how complex it can become when you 
>>> are trying to debug the combination of memory bank switching and interrupts.
>>> 
>>> I had originally wanted to move the VT100 driver into the REX ROM.  This 
>>> would mean that 6 software hook programs would be serviced by running 
>>> software in an option ROM.   So, in active use there would be (1) the main 
>>> ROM (2) the REX ROM and (3) a traditional OPTION ROM. 
>>> 
>>> But what happens when the "system" is running, at the time of an interupt, 
>>> on a separate OPTION ROM, and not either the main ROM or the REXROM?    
>>> This was not anticipated by Mr. Mo Budlong, or if he did think about it, it 
>>> is a "secret".
>>> 
>>> Well I can tell you that I gave up after quite a bit of time sunk into 
>>> debug! OMG.
>>> 
>>> What seems to be most reliable, is to run the "VT100" software hook 
>>> programs in upper RAM, which is how it was meant to work all along.  So, 
>>> for VT100 support you kinda have to live with some memory being taken up by 
>>> that code, which reduces the usable RAM space somewhat.
>>> 
>>> "Typical" REXMGR.BA[http://REXMGR.BA] takes about 0x200 bytes or so without 
>>> VT100, and including VT100 it takes about 0x04B5 bytes. That is more than 
>>> 1k of RAM consumed with enabling both REX and VT100.
>>> 
>>> My prototype shows 28432 bytes free, whereas stock M100 (no REX) shows 
>>> 29638 bytes.  A tradeoff I am personally happy with, for the advantages.
>>> 
>>> I appreciate that many users may not want an LCD plugged into their M100, 
>>> but I personally really like it.  I think large-screen Text, and also 
>>> programming, make it interesting, and still quite compact.
>>> 
>>> Anyhow, happy holidays 2020 to everyone and let us all hope for an improved 
>>> 2021.
>>> 
>>> regards
>>> Steve
>>> 
>>> 
>> 

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