Re: Playing samples on both new and old SIDs

From: Marko Mäkelä (
Date: 2000-07-27 18:14:33

On Thu, 27 Jul 2000, Nicolas Welte wrote:

> First, you can detect a 128 by it's additional hardware and therefore can
> sort out the 8502.

The simplest thing to do is to check whether the data direction register
at location 0 remembers the value you write to bit 6.  The 6510/8500 has a
6-bit I/O port, while the 8502 has 7 bits (and the 7th bit is connected to
the CAPS LOCK a.k.a. ASCII/DIN a.k.a. ASC/CC key).

> You can also distinguish between 6510 and 8500 if the computer is
> without any damage by testing for $de00 compatibility (running
> programs in I/O or colorram space)

Good idea.  Running programs is not necessary; you can just read $de00 (or
better, the high nybbles of the color memory - it's rather unlikely that
anyone has any custom hardware in the color memory area) after
synchronizing with the video chip (e.g. fill $3f00-$3fff with a known
value, blank the screen, turn sprites and ECM mode off).

> But I don't know how to distinguish between 6569 and 8565 from a program.

Neither do I.  Even the "ALWAYS SET THIS BIT TO ZERO" bit works the same
on both chips (setting it has no effect).


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