In DV setup, Performance menu: ticks 2 and 2 or 3 and 3, Optimize
comm: Y, and if you have a 386(or SX), DOS buffers for EMS: 0, unless
you use a network adaptor.
Tell DV that your Telix window is not allowed to swap out, it CAN run
in background, and give it a couple of K of system memory.
Add noff.shr or noff.shp (they are the same program, but the ext name
got changed in DV 2.26) in the shared program section of the DV PIF
for Telix. In some cases, you may help your comm program by adding
noff.shp to something else, such as WordPerfect, which needs it in DV.
If your external modem is running at 9600 bps or above, try to get a
NS16550AFN UART chip for your serial adapter.
If your modem supports flow control and if you lock the modem/serial
port connection (DTE/DCE) at a fixed speed be sure to tell Telix:
auto baud detect OFF, otherwise, set it ON. If you do lock DTE/DCE at
a fixed speed, you will need to turn on flow control. Use CTS/RTS
flow controls if your modem supports it (if your modem manual doesn't
mention it, then it doesn't support it!). (Do NOT use DSR/DTR flow
control on phone lines.)
Shadow ram your video rom, if you can but aren't already.
Tell Telix to use direct screen writes, but tell DV that it does not
write directly to screen. (I know it seems contradictory, but for
Telix 3.12 in DV it's the way to do it).
In Configure Telix, Protocol options, File xfer disk buffer size: use a
small number, 1 to 4, especially if you do not use a disk cache program.
DV PIF excerpts for Telix 3.12 in DV 2.26 QEMM 5
Writes text directly to screen...: [N] (See above discussion)
Displays graphics information....: [N] (ASCII graphics will still work)
Virtualize text/graphics (Y,N,T).: [N] (Y not needed by Telix)
Uses serial ports (Y,N,1,2)......:  or , whichever
Runs in background (Y,N,blank).. [Y]
Can be swapped out (Y,N,blank) [N]