Re: 8501 datasheet / information is wanted :)

From: Gerrit Heitsch <>
Date: Sun, 03 Feb 2013 18:54:06 +0100
Message-ID: <>
On 02/03/2013 05:43 PM, Gábor Lénárt wrote:
> Hi All,
> I've decided to try to build some minimal system based on a 65xx CPU. The
> "best" CPU I have for this purpose seems to be a 8501 from an otherwise
> non-working C16, fortunately it was sockected (I am not sure if it's a
> standard thing being socketed or not).

Problem is, the 8501 is prone to die easily. So the reason why this C16 
is not working might be that the 8501 is dead.

> 8500 is said to be a 6510 exactly, just made with HMOS process instead of


> 8501/7501 is mentioned as used in C16 and Plus4, but it's not mentioned what
> is the difference between these two, and what's the difference between these
> and 8500 (or 6510).

The 8501 has one more bit on the I/O-Port than the 6510/8500 plus a few 
other small details.

> Also what seems to be a magic for me: it's often quoted as an imporant
> feature of 8502 that being capable running on 2MHz, not only 1. However even
> 8501 runs at 1.76MHz (during blanking times, when TED does not need to
> access memory?) in Plus4 so 8501 is allowed to run over 1MHz cleanly, it
> seems. Does it mean that I can run 8501 at about 1.7MHz constantly without
> problems, or this is only the effect that the average clock of a 8501 in C16
> is about 1MHz (slightly more though) and 1.76 is only the peak?

If you tell TED to disable the screen output (border color displayed on 
the whole screen), the CPU will run on 1.7 MHz all the time. The only 
exception being the 5 DRAM refresh cycles happening every can line.

> Currently I am "playing" with an UM6502 (made by UMC) but I would be happy
> to use 8501 instead (the integrated i/o port is great for a hobby project
> like mine!), but I would need some information/datasheet first to understand
> the differences between 8501 and 6502 (there are much more information
> available on 6510, that's why I wamt to compare 8501 with that).

If you really must use a 65xx with integrated I/O, you should use the 
6510/8500. Much easier to get and stable. Also most of them should be 
able to run on 2 MHz. I have a 6510 stamped with an 'A', indicating 2 
MHz capability.

Otherwise... How about using a 6502, a 6532  and an EPROM for the code? 
The 6532 will give you lots of I/O, timer and 128 Bytes of RAM.


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Received on 2013-02-03 18:00:36

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