Designing a 8088 system

Discussion in 'The Projects Forum' started by sausages, Apr 17, 2008.

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  1. sausages

    Thread Starter Member

    Mar 8, 2007
    Hello all!

    I've been set an assignment recently to build a working 8088 system. Now I've spent a few hours reading up on the subject and I think I have most of it down.

    I'm having a few problems with the 16-key keyboard/display interface unit and the programmable I/O interface.
    For the keyboard I'm using a 4x4 key matrix, the output of which is connected to a 8279. The SL pins of this are connected to 2 3-8 decoders ( one of which is fed into the matrix ( pins 0 - 3 ), the other being fed into the LED digit display )

    The interface I'm using is the 8255, I've configured this to be :

    PA - Input
    PB - Output
    PC - Output

    We've been asked for a 8/in 16/out interface in the brief

    My question is to connect these two devices together, am I right in thinking that I will use the output of the 8279 ( PINS OUTB0-3 and OUTA0-3 ) to be the input of the 8255 ( Pins PA0-7 )??

    Also, do the outputs of PB and PC then make their way onto to the CPU's address buffer?

    I've included a diagram of the 8255 that I'm working from. As you can see it has address pins connected to it. I'm still scratching my head try to think of what they do, I've looked at notes but they seem to skip over the A0 - A7. Any help on where to connect them would be much appreciated.

    Thank for now, although I don't think it's going to be the last question I have :L

    I've doubled posted here because I haven't gotten a response on the homework forum and it's pretty urgent
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