EPP for 8 bit isa

[neutrino78x]

I thought you guys might be interested in this, it is not used cards, but original new cards. For example, you can buy a 2 serial port, 1 EPP (bidirectional, high speed parallel) for 8 bit ISA for US$45 (you have to click buy online to see the prices)

Lava Link

Personally, what I would most want is 1 serial and 1 epp, because I already have a serial port on the AST SixPack board.

I would think EPP would be desirable because it speeds up the parallel port, which should be a good thing for parallel port network devices, that is to say, devices that convert a parallel port into an Ethernet port.

eBay auction for a Intel/Xircom EPP to Ethernet

one thing I'm wondering though...there are serial to ethernet things out there...would a PC be able to use that to access the Internet with DSL? or would you have to use the parallel to ethernet instead?

--Brian

 

[mbbrutman]

I have some new StarTech ISA parallel ports that I've been trying to unload. They are 16 bit ISA cards, but will run in an 8 bit slot if you don't use the ECP mode or a high IRQ. EPP mode is much faster than bi-directional because the parallel port hardware does the handshaking on the wires with the remote device instead of making the host machine do it. And I know it works on older machines because I was able to do it with a PCjr. ;-0

Unfortunately, there were several different incompatible implementations of the EPP/ECP setup registers. My parallel port devices don't know how to initialize the StarTech cards for EPP.

In general, bi-directional always works to speed up parallel port devices. I've tested this extensively on a parallel-to-SCSI adapters and the Xircom PE3-10BT parallel-to-Ethernet adapter.

I use the Xircom to connect old machines to networks directly - as far as the machine is concerned, it's a real Ethernet card but it's connected through the parallel port, not a normal bus slot. With TCP/IP software running on your PC and a Xircom on the parallel port you can connect directly to a router, cable modem, DSL router, etc.

The serial-to-Ethernet devices are different in nature. Running a TCP/IP stack right on the machine and sending packets out (whether over the serial port or an Ethernet device) takes a lot of memory and CPU. The serial-to-Ethernet devices help by running the TCP/IP part on an embedded CPU in the device, thus offloading that from the PC. The PC thinks it is just talking directly to a modem, and it is not running TCP/IP at all.

 

[Chuck(G)]

I'll add that for many ISA parallel port implementations, it's often a simple matter to convert a SPP port to a BPP (PS/2 style) port with a trace cut and a jumper. (Yes, that even includes the parallel port on the MDA).

Two things make this possible. The first is that parallel ports are made to be self-diagnostic, that is, circuitry is included to read the data latched on the output. The second is that the register that controls interrrupt enable and the like on an SPP is usually a 6 bit register, with bit 5 unused. Lifting the tristate enable of the data line output latch and connecting it to this bit does the trick and makes the port behave as a bidirectional PS/2 port.

It's always been a mystery to me why IBM waited until the PS/2 to make this minor change.

 

[mbbrutman]

And if you want to see that modification done to a parallel port, I did a nice writeup for the PCjr parallel port sidecar. It can be found here:

http://brutman.com/PCjr/parallel_port.html

Although the page is based on the PCjr sidecar, the implementation of that parallel port is the same as on the IBM monochrome adapter and other IBM parallel ports of the time. You should be able to take the information and apply it to other parallel port implementations that are similar in design.