Re: Turbo232 UART Cart HDL

From: Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de>
Date: Thu, 12 Dec 2013 18:39:15 +0100
Message-ID: <52A9F4C3.4030708@laosinh.s.bawue.de>
On 12/12/2013 06:31 PM, brain@jbrain.com wrote:

> So, I thought about a CPLD solution that would "massage" the 6551
> registers to fit a 16550 or similar device.  But, then, I decided if I
> was going to massage an interface, why not massage the interface to a
> uC.  That would allow many peripherals to be created.
> So, that's my goal.  We'll see how far that goes.  I found some Verilog
> for dual port registers, which seems useful.

Don't forget, that when reading from the 6551-lookalike, you have less 
than 500ns (in a C64) to figure out what the 6502 wants and supply the 
correct data. Not a problem for the hardware, but if you want to emulate 
a 6551 in part with a controller, that's quite tight.

  Gerrit



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