GS/OS High-Speed Serial Port Drivers
                   - Revision 5 (December 2023)
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This collection of six (6) high-speed GS/OS Serial Port Drivers (FileType $BB / AuxType $0002) is intended to be of use when printing from GS/OS Desktop applications using either the Direct Connect PostScript Printer Driver or any of the HP LaserJet/DeskJet printer drivers contained on the Harmonie printer driver software package from Vitesse. (those printer drivers are available and/or linked here: <http://www.apple2works.com/directconnectpostscriptdriver>)

{In addition, these serial port drivers may also be useful when printing to the other brands of printers whose drivers are available on the Harmonie package}.

Since these are serial port drivers, they will probably only be selected when printing in the following two situations:

1. From a 'real' Apple IIgs to a printer with a serial interface (or a printer with a parallel interface using a serial-parallel adapter); or,

2. From an emulated Apple IIgs (e.g. KEGS or one of its variants) to a printer, primarily in the instance where the emulated IIgs' serial port is redirected by the emulator over TCP/IP to a network printer attached to the host computer. {KEGS began offering this feature at version 1.29}.

There are six (6) port drivers in this package:

1. Printer Port (Slot 1) @ 57,600 baud
2. Printer Port (Slot 1) @ 115,200 baud
3. Printer Port (Slot 1) @ 230,400 baud

4. Modem Port (Slot 2) @ 57,600 baud
5. Modem Port (Slot 2) @ 115,200 baud
6. Modem Port (Slot 2) @ 230,400 baud

Included also is the source code (Merlin format) for the drivers.

All drivers are based on Burger Becky Heineman's original freeware 'Printer57.6' port driver released back in the early 1990's, and later included in the Harmonie printer driver software package.

Heineman's driver was disassembled using Ewen Wannop's 'BrkDown' Desktop disassembler application, and then converted into Merlin source code.

A couple of minor items in the Printer57.6 were first corrected, and then the code was modified to produce the six port drivers included here.

The drivers have been tested on both a 'real' Apple IIgs attached to a serial HP LaserJet printer, and also on a KEGS emulated Apple IIgs attached to a networked HP LaserJet printer. 

All tests went well, and all drivers offered substantially quicker printing speed than that achieved by using Apple's own 'Printer' port driver that is included with GS/OS.

To install one or more of the port drivers, just copy the file to the /System/Drivers volume on the boot disk.

To use one of them for printing, access the GS/OS Control Panel from the Apple menu and select the Direct Connect control panel. First select the serial port driver that matches the baud rate you've chosen for your particular printer or your serial to parallel converter. {Note that if you are using KEGS' serial port to direct IP printing to a network printer you can use any speed you wish}.

Then select the printer driver appropriate for your model printer. For a PostScript (or emulated PostScript like Brother's BR-Script) printer (or an auto-switching combination PCL/PostScript printer), select the DCPostScript printer driver, which is a modified version of Apple's LaserWriter driver. Apple's LaserWriter driver has two disadvantages that the DCPostSript driver does not - (i) it only communicates via AppleTalk; and (ii) it is not suitable for use with the versions of PostScript on most modern non-Apple printers.

For a black & white PCL 5e laser printer select the Harmonie LaserJetIII.HAR /  LaserJetIII.FL printer driver. For a color PCL 5c laser printer select the Harmonie DeskJet500C.HAR / DeskJet500C.FL printer driver. For a color PCL 3 inkjet printer select the Harmonie DeskJet560C.HAR / DeskJet560C.FL driver.

One final note: The speed improvements with the PostScript driver are much greater in the emulated IIgs environment as compared to a real IIgs, probably because the speed afforded by the emulator mitigates the slower speed and processing overhead experienced on a 'real' IIgs due to the port drivers using the GS/OS ToolBox routines to send data to the serial port, rather than communicating directly with the serial port hardware.

One possible future improvement to these drivers may involve bypassing the ToolBox routines to communicate with the serial ports directly. In the instance of the Vitesse parallel card drivers included with Harmonie, which send data directly to the parallel card, the speed improvement over Apple's own 'Parallel' port driver, which uses the ToolBox routines, is significant.





Hugh Hood