From: ohland@charter.net   
      
   At first blush, I fantasized there would be a hard number, but with all   
   things IBM, "it depends".   
      
   Output Data Rate page 11   
      
   The approximate time between two data bytes in a DMA operation is   
   5 microseconds, assuming that the attached device returns the   
   ‘-acknowledge’ signal to the ‘strobe’ signal immediately. tn addition,   
   the ‘-acknowledge’ signal is 1.0 microseconds wide (the ‘-acknowledge’   
   signal falls low and not later than approximately 1.0 microseconds after   
   the rising edge of the ‘-strobe’ line).   
      
   To calculate the data rate, the delay from the ‘-strobe’ signal to the   
   ‘-acknowledge’ signal on the attached device side should be added for   
   each transmission. The transfer rate varies according to the DMA channel   
   usage of the system.   
      
   Tomas Slavotinek wrote:   
   > On 10.02.2023 18:51, Louis Ohland wrote:   
   >> So why does software choke on an arbitrated parallel port? Riddle me   
   >> that...   
   >   
   > Eh, disregard my comment about the pin 12 oddity, that of course relates   
   > to the previously discussed 25-pin SERIAL port. Confirmation bias...   
   >   
   > Anyway, there are a few potential problems with the DMA parallel port   
   > (not exclusive to Model 90):   
   > -the connected device does not understand the protocol   
   > -low-level software/driver incompatibility   
   > -configuration/user error (setting the link to ECP or EPP...)   
   >   
   > But data transfers between two PS/2s with Type 3 controllers should be   
   > relatively trouble-free and pretty fast too!   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)