Re: 7501/8501 P5 bit (and DDR)

From: Jim Brain <brain_at_jbrain.com>
Date: Thu, 20 Aug 2020 17:58:52 -0500
Message-ID: <8fcebcda-18f9-78a9-9c0f-0abe3f200a48_at_jbrain.com>
On 8/20/2020 2:45 PM, groepaz_at_gmx.net wrote:
> Am Donnerstag, 20. August 2020, 21:31:30 CEST schrieb Francesco Messineo:
>> Hi all,
>> I am wondering whether or not you can set and read the unused bit P5
>> on the internal 7501/8501 CPU. I don't have a working CPU to make the
>> test.
>> However, I can set and read both the P6 and P7 bits on a 6510 and set
>> the corresponding DDR bits in the register too. If P6 and P7 DDR is 0
>> (so, inputs) the port bits read 0, I assume they're pulled down
>> internally somehow?
>> Can someone make a similar test on a 7501 please?
>> Thanks in advance.
>> Frank IZ8DWF
> on the 6510, all port bits exist and work - they are just not connected to the
> outside world. i'd assume the same for other variants of the cpu.
>
> see here: https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/CPU/
> cpuport/
>
> and yes, it would indeed be interesting to know test results from 7501/8501 :)
>
> --
>
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>
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>
If someone will send a sample app, I am happy to try it on the +4 
sitting here.

Jim

-- 
Jim Brain
brain_at_jbrain.com
www.jbrain.com
Received on 2020-08-21 02:00:03

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