[sdiy] Keyboard scanner IC

[cheater cheater]

> You could say the 6522 is at least as likely to die as the 6511.
> It's closer to the outside world and as such more likely to get
> zapped by ESD. It also gets hotter (than a regular 6502, anyway).

Put a heatsink on it and ground it  - protects from both.

On Mon, Jan 26, 2009 at 8:45 PM, Andre Majorel <aym-htnys at teaser.fr> wrote:
> On 2009-01-26 13:28 -0500, Nathan M. Reeves wrote:
>
>> yes i think the only chip that is bad is the 6500/11 MCU
>> the floppy drive loads samples and the os fine, so the 1772
>> seems to be fine....
>> not sure what the 6522 does, i guess it also has to do with the
>> floppy  drive, which is ok...
>
> The 6522 is a complex chip. It has two 16-bit timers, some 20 I/O
> pins and quite a few functions. Some of those I/O pins could be
> assigned to the rows and columns of the keyboard.
>
> You could say the 6522 is at least as likely to die as the 6511.
> It's closer to the outside world and as such more likely to get
> zapped by ESD. It also gets hotter (than a regular 6502, anyway).
>
> Besides Roy's stash, Western Design Center still make the 6522.
> The 6502.org folks have an account at WDC. I got some 65xx and
> 65xxx chips through them a few years ago.
>
> I have no idea where you could find a 6511. I don't even have a
> data sheet for it.
>
> I don't see an EPROM in the parts list. Is the 6511 OTP or even
> mask-programmed ? If so, pray that it's the 6522...
>
> On a 6502, the SYNC pin will go high when an opcode is fetched,
> which should happen at least once every 7 cycles. If the 6511 has
> a SYNC pin, you could check that. If the clock is good but SYNC
> stays low, it probably means that the chip is dead or stuck on an
> invalid instruction.
>
> --
> André Majorel <URL:http://www.teaser.fr/~amajorel/>
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