Re: Hardware emulation of 6509 using 6502?

From: smf <*smf_at_null.net*> Date: Wed, 15 Nov 2017 13:16:13 +0000 Message-ID: <2041724d-ab8a-319f-eea0-2ddf450ce585@null.net> · smf_at_null.net

On 15/11/2017 11:48, Gerrit Heitsch wrote:
> Illegal Opcodes were never guaranteed. If you want those to work, you 
> have to stick to 6502 from MOS, everyone else might have made small 
> changes to the mask or the process which caused some illegal opcodes 
> to behave differently.

In terms of the second source suppliers, I believe they were under 
contractual obligation to produce exactly what MOS told them & if there 
are variances then you'll see them in MOS chips too.

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