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Thread: DIY Ethernet for Toshiba T1200?

  1. #1

    Default DIY Ethernet for Toshiba T1200?

    Hi,

    The Toshiba T1200 has an internal expansion port. The port is an 8-bit ISA bus with some pins omitted - basically, it has fewer IRQ and DMA lines but all the basic functionality is there. For example, XTIDE with an appropriately modified PCB would work as all required signals are present. At home I have a list of available pins, which is also found in the service manual.

    So, I would like to build an Ethernet card for it, as the original Toshiba LAN cards are impossible to find nowadays. There are single chip ISA Ethernet solutions still in production. I did look at some options and here are my observations. I have not designed anything like this before, so please correct if I'm wrong in my assumptions.

    Cirrus Logic CS8900A

    This one can apparently operate only on a 16-bit ISA bus. It has a 8-bit mode but this disables interrupts completely, so the card would have to be used in polling mode, which wouldn't be nice.

    Davicom DM9000

    If I read the datasheet right, this one can be put in a mode where all data transfers are 8 bits wide. It also claims to be an "ISA to Ethernet MAC Controller", and indeed does have an usable interface. According to the datasheet it could do DMA as well.

    Silicon Labs CP2200

    This one can only do 8-bit data transfers. Looking at it, interfacing this to ISA wouldn't be that hard. No DMA though, but it has a large internal buffer.

    Do you have another chip in mind that would be useful here? Or, even better, has someone already done such a design?

  2. #2

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    microchip ENC28J60. $3 a chip for the DIP28 version so you can breadboard it up. talks over SPI, so you could throw a 5v AVR or PIC in front of it to talk to the ISA bus very easily.
    Into TQFP territory is ENC624J600, which does 10/100 and is parallel as well as SPI, so easier to interface. Microchip haver other controllers going up from there...

    What you havnt spoke of is.. software to drive all this stuff. drivers for windows? packet driver for dos?

  3. #3

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    Thanks for the suggestion! I hadn't even thought of using an MCU in front of the chip - definitely a possibility, even though a "direct" ISA design would be more of something I haven't done before and therefore more rewarding personally.

    TQFP is an option. I am not afraid of soldering SMT and can do pretty small pitches reliably. I'll look into the Microchip offerings as well.

    Software-wise, the T1200 is a 80C86 with 1 megabyte of memory, so a packet driver for DOS would suffice. I am not sure which other Toshiba laptops have the same expansion slot.

  4. #4
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    Have you considered a Xircom PE3 for the parallel port ?

  5. #5
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    I was wondering about the RTL8019AS.

    http://www.ethernut.de/pdf/8019asds.pdf

    I don't know if its still in production BUT:-

    there is lots of documentation as per above, the chip is available reasonably cheaply, its NE2000 compatible on 8 and 16 bit slots. Versatile in its use of IRQ and DMA...

    https://www.semiconductorstore.com/c...dproduct=49189

    (I didn't check P&P etc)
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  6. #6

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    RTL8019AS seems to be easily available. This is another good candidate, not the least because I wouldn't need to write a driver.

    Xircom PE3 would certainly work, but I use the machine mostly for developing stuff connected to the parallel port, so that is more or less reserved.

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