Hy!

As You know from an earlier post I want to rebuild the 65c02-SBC.
But because I'm fairly new in electronics, I don't understand the Bus connectors. In the schematic file, there are fat blue lines labeled A[0...15] and D[0...15]. These seem to be the Data-/Address-Bus, I think. But how to connect them together? Which PIN connector do I have to conenct to which BUS Line. Hope anyone can help me

c.ya

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---===[HeLlRaIsA]===---

"
In the schematic file, there are fat blue lines labeled A[0...15]
and D[0...15]. These seem to be the Data-/Address-Bus, I think.
But how to connect them together?
"

I only had a quick glance at one of his schematics, but every
thing looked straight forward and well labeled (so maybe I'm
missing something in your question)

Generally, all the data lines go to more or less the same places
and the same for the address lines (but only more or less,
there might be 13 address lines that go to all the RAM and ROM
chips and the remaining three going to decoding logic or something
like that).

Rather than draw a mess of lines, eg 16 address lines, you just
draw one fat line and let it represent all of those 15 address
lines. The way you say "address lines 0 through 15" to the CAD
program is (in this case) A[0..15]. That represents 16 individual
traces or wires which will be named A0, A1, etc. up to A15

Of course, you don't want all the address lines going to one pin
so you break out the individual wires from the fat bus wire and
and that individual wire will represent one of those traces and be
named A0 or A1 or A2 etc

So presumably, there will be an A0 wire between the A0 pin on the
processor and the fat address bus wire and an A0 wire between the
A0 pin of the ROM (for example) and the fat address bus wire etc.
and those A0 represent a single A0 trace that connects all the A0
on the various devices.

But mind ya, that's just a convention, in principle you could use
some other name ie you could use bus wire A2 to connect all the A0
and as long as wire A2 (or a wire of what ever name, be it part of
a bus or not) connects all the A0 pins and only the A0 pins it
doesn't matter what you call the wire.

But it would get confusing and the point is to make it less confusing.

And from my glance at the schematic(s) it looked like he has all
those individual wires labeled for what they are ie wire A0 coming
from the fat bus wire and going to an A0 pin on a chip is labeled A0
except where the pin it's self is called A0.


The reason I mention that it's only convention is that some times
it makes sense to to ignore that convention, in the case of
eg an SRAM all the address lines may be, basically, interchangeable
so you might use what the data sheet calls A2 as A0 if it simplifies
the circuit board layout.

The same could be done with a PROM but there might be something
external, ie a PROM programmer, that expects the convention to be
followed. Never the less it can and sometimes is done, eg scrambling
address or data lines to confuse things and make a circuit harder
to reverse engineer. Or just to simplify a layout.

I didn't see any of that in Daryl's schematics, but if I were doing
something just for my self, I wouldn't hesitate to do it.


uh.. what was the question?


(The answer to your question is the schematic tells you which goes
to what.)

Bogax is correct. All address and data bus lines go to the appropriately labeled pin of each device (A0 goes to A0 on the 65c02, 65c22, 28256, & 62256, as does A1-A15 and D0-D7).

Daryl

Thx, now I'll be able to connect the different busses.
But I got another problem with the 65c22 output pins labeled RS0 to RS3.
Due to the schematic, the RS-Pins should be connected to the Address Bus lines 0 to 15. But it doesn't seem logical to me that 4 output lines can be connected to 16 bus lines. Who can help me???

thx

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---===[HeLlRaIsA]===---

RS0-RS3 typically go to A0-A3. So for example if other address lines are used to base the 6522 at address $6000, then the various registers will have addresses from $6000 to $600F, meaning you'll get 16 addresses from the four bits.