Re: OZ-board - the text

From: Martijn van Buul (
Date: 2001-05-10 14:30:49

Ruud Baltissen wrote:
> Hallo allemaal,
> The text. Please, enjoy. I'l return to the @#$#@! decoding of my signals for
> the PC-card :)


So it wasn't my alarm clock which ran at 1 or 2MHz afterall.

Chapeau!, allthough I probably don't have computer which is fast enough
for all this :-/


> As you probably noticed, I mentioned the ISA-bus. What about VLB or PCI? VLB
> is outdated and rare. For PCI you need special chipsets, connectors and more
> advanced tools to create a card. The card must be etched, handwiring is
> because of the involved speeds out of the question. This project must be
> kept in reach of hobbyists.
> ### is above true about special chipset?

Well, the PCI protocol is well defined, but not as easy to implement as the
ISA bus. The *simplest* implementation I saw used an FPGA to do the actual
interfacing to the PCI bus. PCI is defininately not a Geek Port.


> But disabling the hardware interrupt does not mean we are unable to do
> anything else with the PC. The PC can poll the Keyboard-interrupt once a
> while to see if the user wants its attention. If that is the case, it is up
> to the programmer to decide what happens in that case.
> One thing is clear: forget Windows :)
> #### Linux ????

I think you can safely rule out *any* multitasking system. It introduces
latencies and delays which are clearly unacceptible.

> IMHO we can emulate a lot of carts, ranging from some "only EPROM" to more
> sophisticated as the Final Cartridge III or the CP/M-cart for the C64. And
> maybe, repeat maybe, we can emulate the SCPU. What about that? :)
> ###  the 20 MHz worries me a little bit. A faster machine probably could
> handle it. But faster machines often have no ISA-bus anymore. Especially for
> this reason I would be happy if somebody could think of another interface
> which still is "available" for the common hobbyist.

Well, PCI would be the ultimate goal - but it's not "available for the 
common hobbyist" - the smallest problem being the rather tight layout of
the PCI-connector. 

Considering that ISA is a 'depricated' feature, emulating a SuperCPU will
not be easy.

    Martijn van Buul - -
	 Geek code: G--  - Visit OuterSpace: 3333
   Kees J. Bot: The sum of CPU power and user brain power is a constant.
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