Very Computer

Howdy all.....:-)

Firstly I do realize that there are newer/better UARTs available than the 8250
but a 8250 is all I have available right now to experiment with.  :-)

I need an URL to locate a schematic on how to hookup a 8250, 1488 and 1489.
I've spent the last couple of days searching the net but can't seem to turn up
anything except for one schematic that shows the UART but not the 1488 and 1489
connections.

BTW, this schematic shows the timing crystal directly connected (via R/C
components) to the 8250.  Is this correct?  Is there no oscillator (eg 555
timing) or binary counter IC (eg 74HC6040) needed for this UART?

Any information would be much appreciated..........thanks! :-)

--- Sqed/32 1.14/r15155

--- Squish->SOUP by TAM

You can probably use a crystal (can) oscillator to generate the clock for
this.  These connect to power (usually +5V) and ground and have a clock
output that goes to the UART's clock input.  You might be able to get by
with a 555 or some other RC circuit, but it probably won't be as clean and
consistent as a crystal circuit or a crystal oscillator.

Bob

www.saracon.com

------------------------------
You CAN use an oscillator on these UARTs, but it isn't necessary!!

The 8250/16450/16550/etc line of IBM-PC compatible UARTs ALL use a
crystal directly on their pins, and have an internal baudclock divider,
which can be used independent of the UART from its -BAUDOUT output pin,
which is then routed back into the UART in most designs. They often use
a 1.8432 MHz crystal which divides well into common baud rates. The
divisor is programmable internally.
-Steve
--

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