Re: Differences between 8501R1 and 8501R4

From: Gerrit Heitsch <*gerrit_at_laosinh.s.bawue.de*> Date: Thu, 5 Dec 2019 12:59:51 +0100 Message-ID: <a83c7f96-05e8-02ed-e034-0baf4b738cb6_at_laosinh.s.bawue.de> · gerrit_at_laosinh.s.bawue.de

On 12/5/19 12:51 PM, Mia Magnusson wrote:
> 
> Not sure what relationship the 8501R4 has to other MOS/CSG chips though.

Well, it's a 6502 core plus some I/O, rated for 2 MHz (will still run at 
2.2 MHz though (*)). The closest relatives would be the 8500 in the C64 
and then 8502 in the C128.

 From the numbering, the 8500 was started first, but I think the 8501 
came to market first.

(*) Take a PAL system, switch TED to NTSC and disable the display. You 
get no usable video signal, but the CPU runs at about 2.2 MHz, about 
twice as fast as if you run it in PAL mode with the display enabled.

  Gerrit