Re: The ROR bug - seems it wasn't a bug after all.

From: smf <*smf_at_null.net*> Date: Mon, 12 Feb 2024 14:21:12 +0000 Message-ID: <09e7fcb8-8593-4d91-9be2-bd8ad8926aa7_at_null.net> · smf_at_null.net

It's not listed in:

https://web.archive.org/web/20211204234443if_/http://archive.6502.org/datasheets/mos_6501-6505_mpu_preliminary_aug_1975.pdf

But that doesn't prove anything, we could argue that any bug listed in a
bug tracker is not a bug because it's documented.

The ROR instruction ended up using a control bit in the PLA that is
hooked up to some circuits but is essentially unused. It's like they got
to a certain point in development and decided to ship it.

Either they ran out of time, forgot to finish it, or (worse) decided
against including it despite it being trivial to add.

Saying "it's not a bug" misses the point entirely

On 12/02/2024 10:46, Julian Perry wrote:
> Re: The ROR bug - seems it wasn't a bug after all. The final word
> would be if anyone has access to the original 1975 documentation,
> distributed with the original 6502 processes at the Vegas show. I'd
> love to see a copy of that.
>