Re: Replacing the 6502 with a faster chip

["Bill Garber" <willy46pa@comcast DOT net>]

<exegete@nunya.biz> wrote in message
news:4128effb$1_5@corp.newsgroups.com...
:
: Michael J. Mahon wrote:
:
: > Rob Jones replied:
: >
: >>mjmahon@aol.com (Michael J. Mahon) wrote in message
: >>news:<20040820034253.26080.00002251@mb-m28.aol.com>...
: >>
: >>>Rob Jones wrote:
: >>>
: >>>>While surfing the 'net, I found this adaptor
: >>>>(http://www.6502.org/mini-projects/816conv/conv.html) that
replaces
: >>>>the 6502 with a 65C816 processor. I have not done any
research on the
: >>>>65C816, or for that matter the 6502 and its variants, but
is there a
: >>>>way to replace the Apple's 1MHz processor with something
faster?
: >>>
: >>>I expect you want to know if you can make an Apple II run
faster.
: >>>
: >>>The answer is yes, but it takes a lot more than a faster
processor.
: >>>The Apple II video generation is timed by the same clock
that
: >>>creates the processor timing, and the peripheral bus must
: >>>operate at 1.0204 MHz for compatibility.  Some I/O cards
: >>>also require precise code timing for correct operation, most
: >>>notably the Disk ][ Controller for 5.25" disks.
: >>>
: >>>So the trick is speeding up processing without changing the
: >>>bus or video timing and only when speeding up will not cause
: >>>other difficulties--not a simple problem.
: >
: > <snip>
: >
: >>Is the 65C02 a pin-for-pin compatible with the 6502? I could
very
: >>easily make a 3X PLL (3MHz) to clock the "C" while keeping
the bus at
: >>1X (1MHz).
: >
: > Simply clocking it faster will not allow it to interface with
the
: > 1MHz bus and memory interface.  You need to make the rest
: > of the Apple II _completely unaware_ that the processor is
: > running faster, which means that the fast processor must have
: > its own faster memory, either as an associatively mapped
cache
: > or as a complete copy of the content of standard Apple RAM
: > (including any expansion memory if you want to run faster on
: > those accesses).
: >
: > As I said, it is not a simple problem.  Modern FPGA's have
: > enough speed and complexity for a few-chip solution, but
: > the logic design is non-trivial.  I'm not aware of any
publicly
: > available designs.
: >
: > As Roy pointed out, anyone who manages to make, say, an
: > 8MHz or faster Apple II accelerator for less than $80 will be
: > able to sell quite a few (I'd guess 50-100).
:
: I'd say perhaps 200 or more, esp. if sold via eBay.
:
: One way to check is how well Bill Garber does with his memory
card. And
: Bill, I may have a customer for you soon. New IIgs owner
visited me
: yesterday and I showed him your webpage and found your eBay
auction.

Right now I am about 35 boards sold out of 50, so, I'd say at
least 3-4 times as many accelerators would sell at $80-$100.
I agree that 150-200 is not out of the question.

I can always use another sale, thanks.  :o()

: If I needed one, I'd buy one from you.

I know you would, but consider how valuable they might be if
I never make any more and only 50 of them existed.  :o()

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy46pa @ comcast DOT net
Change DOT to a dot to contact me



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