29 Jul
2014
29 Jul
'14
2:59 p.m.
On Tue, Jul 29, 2014 at 2:46 PM, David Riley <fraveydank at gmail.com> wrote:
Along those lines, the 6502 in the Nintendo
Entertainment System
(apparently intentionally) broke the BCD functionality.
[...]
I don't know exactly why they would have done
such a thing, other
than to restrict the target market of the eventual device.
To avoid the need to license the patent MOS Technology had on how they
implemented BCD mode.
The 6502 portion of the NES' 2A03 CPU/sound
generator/etc. chip is
otherwise a copy/paste job of the standalone version; perhaps
MOS offered a cheaper license for chips without BCD?
I don't think they licensed it at all.