Counterfeit ICs, was Re: 6809 vs. 6809E - test-drb@ccmp.vtda.org

3 Jul 2014

In most cases, I find the remarked ICs are actually OK. They're
obviously fakes still (commonly the origin printed on the top is
different to the origin in the casting on the bottom), but functionally
they're fine. This puzzled me initially, but I asked one of the sellers
about this, and he said that it was done because the process of removing
the ICs from the boards often marks or damages the printing. So the
standard process involves remarking, straightening the legs to factory
original angles, and re-tinning. It results in used ICs that look new.
Sometimes they're sold as 'remanufactured' (which is sort of accurate),
other times they're sold as new, which is obviously untrue. I'm not that
bothered so long as they work, though I probably should complain about
it. 
On 3/07/2014 9:03 a.m., Tony Duell wrote: 

...
  This is becoming real problem. The remarked
devices, of course, have no relation to what they
claim to be, they can't possibly work. Heck, I once enqired about a
replacement for an HP custom IC and was asked 'what package, and how
many pins'. Given this device had only ever existed in one pacakge, with
one particualr pin count, it wa obvious I was goign to get a fake. I do
wonder why they botyher. They can't make that much money selling to
hobyists, surely no commercial company wants such fakes. 
...

> I spent a while looking
...
 > over the datasheets of the 68B09 as compared to
the 68B09E. It's obvious
...
 > that there's some difference in the way the
timing works, but I haven't
...
 > been able to come to any firm conclusions
what the exact difference is,
...
 > and what purpose it serves. The best I can
do is that it's related to
...
 > synchronization with some external devices.
...

 he difference is where hte clock circuitry is. 

 The 6809 (normal and E_) need a pair of clocks in hase quadrature. The E 
...
  clock (Enable) and the Q clock (Quadrature).
FWIW, the 'clock rate' of

...
  the 6809 is specified as the frequency of these
clocks

 The 6809 (on E) has an internal clock generator. It can be driven by a 
...
  crystal of 4 tiems the CPU clock rate (soe a
68B09 can use an 8 MHz 
...
  crystal). The E and Q pins o nthe chip are
outputs
...

 The 6809E (E=External) has no internal clock generator. The E and Q pins 
...
  are inputs, to be driven by an extgernal circuit
that produces the 
...
  approrpatie signals in phase quadrature. 
...

 IIRC, i f you use the 6883 SAM (DRAM controller) you prettty much hace to 
...
  use the 6809E. The SAM generates E and Q, and
expsects to eb able to 
> synchroinse the CPU to them.
...

...
 > So - can anyone explain
> the difference, in terms that aren't too hard to understand? And - is
...
 > there any hope of modifying a machine that
would normally require a
>> 68B09E to be able to use a 68B09?
> 
...
  That depends on the circuitry around the CPU.
However, if it sues the 
...
  6809E CPU, it's a fair bet it is goign to do
oomething odd with E or Q

> (perhaps stretchign one of them when acessing slower memory or 
...
  something). In which case, tryign to use the
plain 6809 is goignt to be
a 
...
  lot of owrk. The 6809E was origianlyl chosen for a
reason, after all (and 
...
  I doubt it was cost, the cost of the external clock
curcuit would 
...
  outweight any difference in price of the 2 chips when
new), so the reason 
...
  is more likey that said clock circuit does soemthing
extra that can't 
...
  easily be done wit hthe plain 6809.

 -tony 