Hello,

Does anyone know whether there is an updated, faster version of the
6510, 7501/8501, and 8502 CPUs available?  I am looking to find a
drop-in replacement for the 8501 CPU on my Commodore Plus/4 to
something faster.

There are lots of updated (faster) 6502 CPUs available, but these do
not have the 6510-specific features.  Anyway, any information would be
appreciated.


Thanks,
krenin

What would be the point? The clock comes from outside of the CPU. The
speed rating of a part is a maximum, a 6510 will always run at 1.022MHz
in a NTSC C64, no matter what the speed of the part.

krenin@gmail.com writes:

> I am looking to find a drop-in replacement for the 8501 CPU on
> my Commodore Plus/4 to something faster.

What makes you think that a higher clocked CPU would work as a
drop-in replacement? Don't you need to change a crystal as well
to even theoretically increase clock frequency?

-- 
Anders Carlsson

krenin@gmail.com wrote:
> Hello,
> 
> Does anyone know whether there is an updated, faster version of the
> 6510, 7501/8501, and 8502 CPUs available?  I am looking to find a
> drop-in replacement for the 8501 CPU on my Commodore Plus/4 to
> something faster.
> 
> There are lots of updated (faster) 6502 CPUs available, but these do
> not have the 6510-specific features.  Anyway, any information would be
> appreciated.
> 
> 
> Thanks,
> krenin
> 
Well, the 650x family has been pretty much discontinued, but there 
should exist some pin-compatible chips.

Your plus/4 would be running with a more modern processor, but it would 
be exactly the same speed... So the point would be moot.

Even if you swapped out the crystal supplying the phi clock (the main 
cpu clock for 650x family processors) the thing wouldn't work at all, 
because the i/o chips (video, audio, peripherals) are designed for a 
specific clock rate and won't work properly otherwise.

Now, you COULD do some CPLD programming and design a replacement, 
possibly  with a PLL clock multiplier, so that the CPU performs each 
opcode in one standard clock cycle. That'd speed things up a tad...
-Urson Bear

OK, I wasn't sure whether the newer 650x compatible processors have
internal and external clock frequencies (using multipliers)... So I
guess they don't.  So it looks like I would need a circuit in between
the upgrade CPU and the Plus/4 board.  Also, another thing I was
wondering about is the function specific to the 6510 variants where it
quickly loads in the ROM areas into RAM when starting the system, and
can unload it the same way.  I think that the 650x upgrade processors
do not generally have this feature, as far as I know...  So I guess it
would take a separate circuit to implement that feature as well?  I
guess that function could be put on the CPLD also.

I want to use the Plus/4 systems to develop some custom stuff for
personal use and I think that eventually I'll be wanting to upgrade
them in various ways... So was just wondering.

Also, I was wondering whether there is any way to squeeze more RAM onto
the Plus/4 board, if an upgrade CPU such as C65816 (having higher
memory addressing), assuming that the CPLD circuit was in place to
allow the CPU upgrade in the first place...  If the chips can't fit on
the board, this could be done with an expansion card...


krenin

"OK, I wasn't sure whether the newer 650x compatible processors have
internal and external clock frequencies (using multipliers)... So I "
You make it sound like they just stopped production last year. It's
been 15 years. The PLL in modern clock multipliers uses more
transistors than are in the entire C64.

"6510 variants where it quickly loads in the ROM areas into RAM when
starting the system,"
What? It's just a signal that goes to a PLA to shuffle the memory map
around. The CPU doesn't "quickly load" anything.

"I want to use the Plus/4 systems to develop some custom stuff for
personal use "
Good heavens, whatever for? One mistake and you smoke irreplaceable
hardware.

"Also, I was wondering whether there is any way to squeeze more RAM
onto
the Plus/4 board, if an upgrade CPU such as C65816 (having higher
memory addressing), assuming that the CPLD circuit was in place to
allow the CPU upgrade in the first place...  If the chips can't fit on
the board, this could be done with an expansion card... "

Why? You're re-designing the whole thing from the ground up at that
point, probably with equally obsolete parts. Why? What's wrong with any
of the dozens of modern microcontrollers with a bazillion features and
clock speeds in the 40MHz region?

No offense, but why don't you spend six months to a year learning the
basics, then come back to us? You sound like you need to do a lot of
learning before plugging in that soldering iron.

"No offense, but why don't you spend six months to a year learning the
basics, then come back to us? You sound like you need to do a lot of
learning before plugging in that soldering iron. "

Oh, it's just something that I was wondering about; I didn't say that I
was just about to jump right in there and start building parts.
Obviously I have a lot to learn, anyway I just wanted to know whether
it was possible...


krenin

krenin wrote:
> OK, I wasn't sure whether the newer 650x compatible processors have
> internal and external clock frequencies (using multipliers)... So I
> guess they don't.  So it looks like I would need a circuit in between
> the upgrade CPU and the Plus/4 board.  Also, another thing I was
> wondering about is the function specific to the 6510 variants where it
> quickly loads in the ROM areas into RAM when starting the system, and

I'm not aware of any 02 variant that does that.  Can you provide a link 
to details?

Jim

Hi Jim,

Here's a link about it:

http://www.atarimagazines.com/compute/issue52/288_1_READERS_FEEDBACK_6502_6510_DIFFERENCES.php

krenin

krenin wrote:
> Hi Jim,
> 
> Here's a link about it:
> 
> http://www.atarimagazines.com/compute/issue52/288_1_READERS_FEEDBACK_6502_6510_DIFFERENCES.php
> 
> krenin
> 

Ah, THAT.  When I read:

"Also, another thing I was
wondering about is the function specific to the 6510 variants where it
quickly loads in the ROM areas into RAM when starting the system, and
can unload it the same way.  I think that the 650x upgrade processors
do not generally have this feature, as far as I know...  So I guess it
would take a separate circuit to implement that feature as well?  I
guess that function could be put on the CPLD also."

I thought you were stating that the CPU transfers the ROM information 
into RAM (the use of the word "loads" for example).

Actually, the 6510 doesn;t bank memory per se, it just has an on-board 
IO port, much like all newer uControllers do.  It just so happens that 
the outputs of that port are tied into the address decoding logic in the 
64 and 128.

The B128 and other CBM machines had similar ports on the 65XX CPU.

However, as you state, a bit of VHDL/Verilog exposing a DDR and a PORT 
at locations 0 and 1 would work just as well.

Jim

"krenin" <krenin@gmail.com> writes:

> Also, I was wondering whether there is any way to squeeze more RAM onto
> the Plus/4 board,

I'd believe this is a bit easier task than increasing execution
speed, at least if you suffice with bank switching.

Ruud Baltissen, a CBM oldtimer, has some interesting but not always
complete hardware projects on his homepage. If you really have the
skills and motivation to design some hardware upgrade to your Plus/4,
perhaps some of the projects are of value; if nothing else to show
you what can not be done easily.

http://www.baltissen.org/htm/hardware.htm

-- 
Anders Carlsson

Oh that's OK, just don't threaten to junk relatively rare computers
like the +4 for ill-defined personal projects... I mean, you could
ground a TIG welder to the motherboard and run the electrode across the
PCB as a "personal project". :)

<a7yvm109gf5d1@netzero.com> wrote ...

> Oh that's OK, just don't threaten to junk relatively rare computers
> like the +4 for ill-defined personal projects... I mean, you could
> ground a TIG welder to the motherboard and run the electrode across the
> PCB as a "personal project". :)

That sounds like a good project to use Spectrums for!    ;-)
-- 
Best regards,

Sam Gillett

Change is inevitable,
except from vending machines! 

"Oh that's OK, just don't threaten to junk relatively rare computers
like the +4 for ill-defined personal projects..."

OK, I didn't.

"I mean, you could
ground a TIG welder to the motherboard and run the electrode across the
PCB as a "personal project". :)"

I guess you could, but that would be dumb.


krenin

Hi,

More memory in the Plus 4 is possible. I have 4 Plus 4's with 256k of
ram and custom chips.  But I agree with the others in this thread, take
your time and do some research.  I you want any support on a Plus 4
project, why not pop over to www.commodore16.com as we have several
hardware projects on the go at the moment.  The forum is full of 264
hardware & software information and all are welcome :)

Regards,

Chris

""Oh that's OK, just don't threaten to junk relatively rare computers
like the +4 for ill-defined personal projects..."

OK, I didn't. "

The fact that you wanted to replace and re-engineer the whole thing
from the ground up = destroying.

""I mean, you could
ground a TIG welder to the motherboard and run the electrode across the
PCB as a "personal project". :)"

I guess you could, but that would be dumb."

Ever tried it? You can tell exactly which parts are exploding by the
sound. Chips make a very dry, loud cracking sound, hitting a ground
plane makes the welder hum a bit louder followed by a small fire on the
PCB, electrolytic caps make a high pitched whistling sound just before
they explode like a firecracler, and resistors make a delicate, popcorn
kind of sound.
I wonder what would happen if I used an oxy torch instead?

I upgraded the RAM in my Plus/4 by plopping some SRAM chips in space
where the 3-plus-1 software ROMs were and running a line from the CPU
/Write to the chips'  /Write line.    I was doing it with the intent of
creating battery-backed RAM, but never quite got the battery backed
part to work.  But it seemed to store the information fine while the
system was turned on.  Its an easy way to add some more RAM.

"David Murray" <adric22@yahoo.com> wrote in message
news:1147800678.205067.28750@y43g2000cwc.googlegroups.com...

> I upgraded the RAM in my Plus/4 by plopping some SRAM chips in space
> where the 3-plus-1 software ROMs were and running a line from the CPU
> /Write to the chips'  /Write line.    I was doing it with the intent of
> creating battery-backed RAM, but never quite got the battery backed
> part to work.  But it seemed to store the information fine while the
> system was turned on.  Its an easy way to add some more RAM.

David, have you checked out the BQ4830Y from TI?
http://focus.ti.com/docs/prod/folders/print/bq4830y.html

It's an RTC chip which looks like normal RAM/ROM.  And the pinout matches
most ROMs so you can simply drop it in place.

Best of all, you get 32K of battery-backed SRAM (minus the 8 bytes for the
RTC function) with the battery and everything in 1 package.

I just put one of these in my PET's option ROM socket (using Nicolas Welte's
excellent 24/28 ROM adaptor), and it works fine.  I can read the time by
simply PEEKing the values in memory.  I even stored some ML routines in the
SRAM for easy always-there access.

Surely there's a battery-backed SRAM chip out there (like this but without
the RTC function) that you could use for your Plus/4.

Regards,
Leif

Hey Krenin,

   http://www.westerndesigncenter.com/wdc/ is the place to go to
research the latest 65xx designs and implementation thereof - if I
remember correctly the 6502 is still pin compatible but the 6522's are
not, and they do not make a 85xx compatible chip. Still, it's a good
resource for information on the 65xx family and most of the information
you'll find in the 6502 datasheet is still applicable to the older 65xx
chips. Good luck with your ideas and don't let a little thing like 'tig
welders' stop ya <g>... If you're new to microcontrollers and
microprocessors in general but familiar with BASIC then a good place to
start your exploration of the world of micro's is with the Basic Stamp
from Parallax (http://www.parallax.com) or the PIC from Microchip
(http://www.microchip.com). Parallax has a Stamps In Class program that
is a good start for the hobbyist interested in micro's, but the PIC's
are far less expensive, are more widely supported, can be programmed in
either assembly or C and microchip is pretty nice about giving away
samples (whereas Parallax is not). The Basic Stamp is essentially a
custom PIC implementation with a BASIC language interface that may be
more comfortable to get started with if you don't know assembly or C
though and they have a fairly decent introduction to the world of logic
as well. Speaking of logic, Xilinx (http://www.xilinx.com) has a fairly
inexpensive CoolRunner-II design board that will get you started in
CPLD's (and other boards for ASIC and FPGA as well) which are
programmable logic devices - to put it in perspective you could build
an entire +4 out of a CPLD these days minus a few external parts. The
above sites should get you well on your way in the world of micro's, if
it doesn't just make your head pop from all the information you'll
glean! 

-- Denny

> Surely there's a battery-backed SRAM chip out there (like this but without
> the RTC function) that you could use for your Plus/4.

Actually, I am sure that would work fine in the Plus/4.  But the reason
I was doing it was because I wanted to use the Plus/4 for a specialized
purpose (The main computer in a spaceship I'm building in my backyard..
it is just for playing in, it doesn't fly)  and I wanted to have an
instant-on to my program.  I figured the battery-backed RAM would be an
easy alternative to buying or building an eeprom programmer.

However.. I have found the Commodore DTV to be a better solution.  I am
using the board out of a hummer off-road racing game since it has a
user-port available.  And it has FLASH_RAM that I can store 2 MB of my
own software in.. so it is a much better solution than the Plus/4.