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Amiga Explorer and Parallel Port

 

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Q: Does Amiga Explorer support parallel port connections?

 

DISCUSSION

A: Amiga Explorer directly supports TCP/IP connections and serial port connections (without TCP/IP software), but not parallel port connections.

Parallel port data transfer does indeed have the potential to be faster than serial port communications. However, unlike serial port and TCP/IP connections, which are well-supported by the different operating system versions, implementing a parallel port interface for bidirectional data transfer, if at all possible, always was a more complex task than using the parallel port just for printing. Also, the Amiga parallel port has an unbuffered direct connection to the 8520 CIA I/O chips, which can easily lead to damages (e.g. by a static discharge).

In 2020 we again did a comprehensive review of available USB to parallel adapters available for the PC side, also checking with manufacturers, and concluded that these adapters, which were mainly designed for printing under Windows, are not suitable for bidirectional data transfer. If such a cable was available, it would be desirable that it featured a buffering or other isolation mechanism, to protect the fragile parallel port circuitry of Amiga computers.

Conversely, USB to serial (not parallel) adapters work great with the Windows side of Amiga Explorer.

Indirectly, Amiga Explorer supports all devices and connections for which TCP/IP drivers exist for both the Amiga side and the Windows side. This means that it is in theory possible to use Amiga Explorer over all connection types which are supported by TCP/IP, including Ethernet networks and serial and parallel cables. In practice, TCP/IP is normally used only for Ethernet connections, because serial connections can also be handled directly by Amiga Explorer (without the need to install and configure TCP/IP and the serial line IP driver, or SLIP), while parallel line IP drivers (PLIP), which would allow the Amiga and Windows to establish a TCP/IP connection over a parallel cable, have probably been taking so much longer than SLIP to develop and become available on various platforms, for the same reasons that led to Amiga Explorer not directly supporting the parallel port.

Historically, some Amiga applications (e.g. the excellent PC2Amiga by Michal Kara, who graciously assisted in this research) offered bidirectional data transfer support over the parallel port. But this required "banging the hardware" on the PC side, and only worked with the original (non-USB) parallel port hardware. What was possible on DOS and Windows 95/98, stopped working on Windows NT 4.0, Windows 2000 and later versions. This was the main reason why Amiga Explorer did not originally support a parallel port connection.

Amiga Explorer already offers good, system-compliant support on all operating system versions and for both low and high speed connections over the serial interface (19.2 kbit/sec to 115 kbit/sec) and TCP/IP (up to several Gbit/sec, using WiFi or Ethernet), including USB and wireless links when a USB or a Bluetooth serial adapter is used. Where speed is required, Ethernet currently offers not only the best performance, but also the best price/performance ratio. Additionally, PLIP drivers which could immediately be used by Amiga Explorer for a parallel port connection using TCP/IP may be coming soon.

When TCP/IP is installed, serial and Ethernet connections can be used by multiple protocols at the same time, for example for Amiga Explorer and to share a modem for internet access.

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Article Information
Article ID: 13-135
Platform: Amiga, Windows
Products: Amiga Explorer, Amiga Forever
Additional Keywords: IEEE 1284, null-modem
Last Update: 2020-01-15
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