6502.org

Main threads:
6509 dissection
8501 dissection

Side quest:
This thread is a comparison of the 6509 and 8501 clock generator, brought to you by Frank Wolf and ttlworks.

Because the official MOS 6509 datasheet contains an error (PHI1 and PHI2 inputs swapped),
I felt a need to take a closer look at the 6509 clock generator.

;---

Results for the 6509 in short form:

Pin 40 is PHI1_in.
Pin 38 is PHI2_in.

Both pins drive the circuitry inside the 6509 directly/unbuffered.
Each pin has an ESD protection FET.

TTL circuitry for driving the PHI1_in and PHI2_pin of the 6509 can be found in the P500 PET-II schematics.

Eagle 6.4 schematics for my schematic pictures in this thread,
just in case if somebody needs them.

Note: KiCad is supposed to be able to import these schematics,
unfortunately it doesn't seem to be possible to disable the layers 'name' and 'value' in KiCad schematics,
so making my schematics look nice and clean in KiCad will require some work, sorry.

The silicon of the clock generator in the original 6502 looks completely different
from what we have in the 6509 and 8501.

Since the 6509 was manufactured in an older process technology than the 8501,
it's an interesting question if the first revision of the 6509 did "rocket testing"
for the clock generators of the later MOS CPUs.


When comparing the silicon of the 8501 and 6509 clock generator in one picture,
it appears that some of the parts in the chip layout look quite similar for both chips.
In the 6509, the clock generator circuitry is only dead weight:
Some vias are placed differently than in the 8501.
Quite some vias that connect to VCC are missing.
Outputs of all of the driver transistors are not connected to anything.
In the PHI2 driver, gate of the FETs (not) switching PHI2 to GND and gate of the FET (not) switching PHI2 to VCC are tied together.

8501 clock generator:

6509 clock generator:

That's all for now.

Now back to dissecting the 6530 clock generator...

Once again I have to admit that your speed and precision is astonishing!

Great (ttl)works as always.

Thanks for the kind words.