Re: Disabling memory refresh in UltiMax mode Re: 6510 handling of $00 and $01 registers

From: Segher Boessenkool <>
Date: Fri, 9 Dec 2011 03:18:37 +0100
Message-Id: <>
>>> If I remember correctly, I sent the chip to be read. It was from my
>>> oldest C64, serial number 32xxx, with ceramic DRAM chips (350ns  
>>> IIRC)
>>> and 6569R1 and so on.
>> An antique!
> Not only that, but the 6569R1 can be detected by software, at least  
> this program can do it:
> With a 6569R3 or newer, it will just show '6569', but is somehow  
> able to detect the R1 and list it. It is also quite good at  
> detecting the rest of the hardware. With some I have no idea how it  
> does it though.

Excellent fun!  It sees if the light pen interrupt can be triggered
between raster lines x'136 and 2; if so, it's a 6569R1, if not, not.

The 8565 vs. 6569 test seems to be if sprite-background collision
is triggered for a sprite with ECM colour 2 (bits 10) (on 8565 it
is, on 6569 not).

The discrete vs. CMOS core logic thing seems to check whether flipping
the VIC address space (VA15,VA14) glitches (doesn't on the CMOS).

The VIC-IIe check is just testing for reg 30.  Boring :-)

6526 vs. 8521 CIA checks exactly how long it takes a timer to trigger
(8521 is a clock cycle earlier it seems).

6581 vs. 8580 SID test checks the exact sawtooth waveform (first
mode 7f, then mode 20, then it checks)?

> Demos written for the 6569R3 or higher look quite odd on the R1.

Because of the luminance palette difference, I take it?  Or is there
some more awesome difference :-)


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Received on 2011-12-09 03:00:08

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