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Fastest Parallel port card

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    Fastest Parallel port card

    What is the best parallel port card I can get for my model 25?

    I'm ready to sacrifice the SoundBlaster in it, for a better parallel port card, so my external hard drive goes much faster.
    IBM PS/2 Model 25, NEC V30 8MHz, 640KB RAM, ATI VGA Wonder XL, 2GB SSD, Ethernet, DR DOS 6/GeOS, Xircom PE3 Ethernet

    #2
    I presume that the existing parallel port is at least bi-directional.

    The next step up would be EPP. EPP improves the handshake between the machine and the device, increasing the speed of the transfer. I've run EPP ports on a PCjr.

    ECP would be the top of the line, but these require DMA which might be tight on your system. (It is effectively an XT, so there is not a lot to go around.)

    Comment


      #3
      The port on my model 25 is reported as uni-directional according to my hard disk driver, and the 20kbps file transfers via ftp are getting old now fast..
      IBM PS/2 Model 25, NEC V30 8MHz, 640KB RAM, ATI VGA Wonder XL, 2GB SSD, Ethernet, DR DOS 6/GeOS, Xircom PE3 Ethernet

      Comment


        #4
        At one point I was under the impression that all PS/2 parallel ports were bi-directional. Apparently that is not the case ..

        What we really need is an 8 bit ISA card for "limited" machines that includes XT-IDE and Ethernet.

        Comment


          #5
          XT-IDE was nice, but the fact I have to make it myself, forget it, I don't even have an EEPROM burner.

          I can't find a single EPP parallel port card that would work on XT's at all, like they don't exist.
          IBM PS/2 Model 25, NEC V30 8MHz, 640KB RAM, ATI VGA Wonder XL, 2GB SSD, Ethernet, DR DOS 6/GeOS, Xircom PE3 Ethernet

          Comment


            #6
            The Model 25 has a bidirectional printer port; it just doesn't work the same way that the other (higher) models do. According to the Model 25 Technical reference:

            To allow the parallel port to receive data from external devices, disable the output buffer by writing a 0 to bit 7 of the System Board Control register.
            This is a bit different from the other PS/2 models, which use bit 5 in the printer port control register to change the direction. This is port 65 (hex) and is configured thus:
            Code:
            Bit  Function 
            7  Parallel Port Output Enable 
            6  Reserved  =  0 
            5  Reserved  = 0 
            4  Serial CS 
            3  Diskette CS 
            2  Video CS 
            1  Parallel Port CS 
            0  Fixed Disk CS
            So, you'd read port 65H, then clear bit 7 and write the byte back to enable input.

            The PS/2 TRM for the Model 25 is on bitsavers.
            Last edited by Chuck(G); April 18, 2011, 09:15 AM.
            Reach me: vcfblackhole _at_ protonmail dot com.

            Comment


              #7
              Originally posted by evildragon View Post
              I can't find a single EPP parallel port card that would work on XT's at all, like they don't exist.
              Actually, almost any simple printer port (that uses simple SSI TTL) can be changed to provide EPP with a cut and jumper, including most cheap Taiwanese boards as well as both the IBM printer adapter and the IBM MDA.

              It's been discussed here.
              Reach me: vcfblackhole _at_ protonmail dot com.

              Comment


                #8
                Hmm ... I'm confused (again).

                My understanding of the bi-directional parallel port is that an LS374 is usually wired to always output data, not to read it. The modification on the MDA card and similar designs (including the PCjr parallel port sidecar) is to put the LS374 under software control such that it can be told to both read and write.

                What does that bit on the "System Board Control Register" do - does it just enable/disable the write to the control port on the parallel port to change the direction of the LS374 (or equivalent) ?

                Comment


                  #9
                  Parallel port for an external hard drive?
                  Why not SCSI?
                  [Need something to waste time on? Click here to visit my YouTube channel CelGenStudios]
                  --------------------------------------------------------------------------------------------
                  [No time for videos? Click here to visit my Twitter feed @CelGenStudios]

                  = Excellent space heater

                  Comment


                    #10
                    Originally posted by mbbrutman View Post
                    What does that bit on the "System Board Control Register" do - does it just enable/disable the write to the control port on the parallel port to change the direction of the LS374 (or equivalent) ?
                    Well, the parallel port always is in input mode, so you just tristate the output buffer (374). The thing with the 25 is that the control bit was moved to bit 7 of port 65h. Don't ask me why--I don't know. But writing that bit has the same effect as writing bit 5 in the "normal" EPP control register.

                    Too bad that not many software vendors knew about it.
                    Reach me: vcfblackhole _at_ protonmail dot com.

                    Comment


                      #11
                      Originally posted by Chuck(G) View Post
                      Well, the parallel port always is in input mode, so you just tristate the output buffer (374). The thing with the 25 is that the control bit was moved to bit 7 of port 65h. Don't ask me why--I don't know. But writing that bit has the same effect as writing bit 5 in the "normal" EPP control register.

                      Too bad that not many software vendors knew about it.
                      That seems like a case of criminal stupidity ...

                      On a normal parallel port the control register for the port is at the base address + 2, and it's the 5th bit in that port that controls pin 15 on a 174 , which can then be used to control the 374. Moving that bit to port 65, bit 7 makes no sense at all, and no wonder why nothing that checks for a bi-directional port on a Model 25 can detect it ...

                      Thanks for clearing that up.


                      Mike

                      Comment


                        #12
                        So then literally the only thing would be to either find a way to modify the driver to access it correctly (it's a .sys driver in config.sys), or just get a new card.

                        As for SCSI, I don't have any enclosures and would rather an extra parallel port anyway..
                        IBM PS/2 Model 25, NEC V30 8MHz, 640KB RAM, ATI VGA Wonder XL, 2GB SSD, Ethernet, DR DOS 6/GeOS, Xircom PE3 Ethernet

                        Comment


                          #13
                          Originally posted by evildragon View Post
                          So then literally the only thing would be to either find a way to modify the driver to access it correctly (it's a .sys driver in config.sys), or just get a new card.
                          Yup, that's pretty much the case.
                          Reach me: vcfblackhole _at_ protonmail dot com.

                          Comment


                            #14
                            Hmm, any takers on modifying the driver for me? Or teach me how its done. Sounds like its just one hex string that needs to be changed.
                            IBM PS/2 Model 25, NEC V30 8MHz, 640KB RAM, ATI VGA Wonder XL, 2GB SSD, Ethernet, DR DOS 6/GeOS, Xircom PE3 Ethernet

                            Comment


                              #15
                              It may just be a fluke, but yesterday i picked up an 8 bit serial/parallel/game port card. Its brand new in box, the shrink wrap is still sealed. I got it because it was sealed and $10. It "features" a bi-directional printer port and claims it will work in any AT compatible slot. Its made by Siig, whom I believe are the best at what they do. Model IO1802. Google brings up nothing of value on a search. I have a late model Siig card that has 16550 uarts in my 386 and it can easily saturate the isa bus with just the hard drive...

                              Its one of those things thats just going to sit on my shelf and look pretty, let me know if your interested.
                              It is a mistake to think you can solve any major problems just with potatoes.

                              Comment

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