Hi Tom,

> On Mar 26, 2023, at 5:57 AM, tom ehlert <t...@drivesnapshot.de> wrote:
>> For
>> instance, vecho (which displays many user messages, like “Welcome to
>> FreeDOS”) don’t output text the same way as other programs and do not get 
>> captured at present.
> I don't know how and why vecho displays text different. However it
> could "display" the text twice: once in the complicated way, and once
> in a "do nothing" way intercepted by your logger.

Thats easy enough for me to explain. :-)

Most stuff uses DOS interrupt calls to output text. In turn DOS itself displays 
that text through the BIOS Teletype Output [1] function (int 0x10, function 

VECHO (part of V8Power Tools) does not use that interrupt function to display 
text. Those programs uses multiple BIOS interrupts to move the cursor 
around[2][3], display text[4] and scroll the screen[5]. They use those 
functions (instead of the simple Teletype output) to support windowed like 
behavior needed by the FreeDOS installer. It allows them to write text inside 
“window” boxes and such things. 

A more general method will be to just grab stuff as it scrolls off the screen, 
or when the screen is cleared. Then as long as a program is not directly 
managing video memory for the scroll, any text (even if written directly to 
video memory) that is displayed will be captured. 

But, I definitely plan on adding a “add to log” function in the driver. This 
will permit the interface program to directly write messages and allow 
redirecting individual program output to the log. All of which will be very 
useful in the FreeDOS installer and permit capturing output from programs like 
FDISK for trouble shooting installation problems.

>> There is a lot of other stuff that I’d like to get done with Logger
>> for the T2304 Interim Build. But, those are not critical functionality.
> cool would be a single logger.exe, useful both as
>  device=logger.exe
> and
>  c:>logger.exe
> later

For now, I’m going with two files, the driver a SYS and interface a COM. 


But, there are a couple of advantages to just having a single EXE. 
So eventually, it will most likely move to that file format. 

> Tom



[1] - https://fd.lod.bz/rbil/interrup/video/100e.html#140
[2] - https://fd.lod.bz/rbil/interrup/video/1002.html#121
[3] - https://fd.lod.bz/rbil/interrup/video/1003.html#122
[4] - https://fd.lod.bz/rbil/interrup/video/1009.html#133
[5] - https://fd.lod.bz/rbil/interrup/video/1006.html#130

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