This is something every programmer (and system designer) should play with at least once to appreciate it, I've always thought.

Being able to copy the ROM to RAM, then turn off the ROM, and modify the ROM code, all in the same memory locations, without changing the PC, is just plain slick.

Splendid! I can update the version on this site, with your permission.


Agreed, a very useful tactic. I think Bil Herd's recent talk on the C128 was very critical of the 6509's banking - when designing these things, there's a balance between ease of implementation and ease of use which is worth making an explicit effort to get right. If you haven't tried to use something, it's hard to guess how easy it is to use.

Then you'd probably like my POC V2 unit:


It is possible to map out high ROM ($00E000-$00FFFF, aka HIROM) to expose the RAM underneath, which, logically enough, is HIRAM. Correspondingly, the ROM at $00C000-$00CFFF is LOROM. When either ROM is mapped in a write in that ROM's range will "bleed through" to RAM at the same address. It is also possible to write-protect HIRAM, which means HIROM could be copied to HIRAM (using the '816's handy MVN instruction) and the firmware run out of RAM, avoiding the need for wait-stating ROM accesses.

Similar to the above, one could map out the I/O block to expose the RAM in the same range. That feature was more of a logic design exercise for me than an attempt to satisfy a fulminating need for more RAM. Obviously, a running system needs its I/O hardware, so the actual value of that RAM would be questionable.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Please do!

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Done! See PM for details.

The 6509 is an interesting part of history that I hope doesn't get forgotten. It was precisely what most people in the industry wanted, at least from what I was aware of at the time. It just turned out to be nowhere near as nice in practice as it was in theory. I highly suspect that Apple would have used it in the /// if it had been available to them, and if they weren't already so scatter-brained in that project.

Alas, I hope to find more time to get on with my 6509 project. I had to move twice, time is scarce... But 6509 is a very strange construction. I played with the thought to get a CBM 6xx/7xx but they are far too expensive, moon-prices for collectors.

I think you can get one now for less than I paid for my B128 before the floodgates opened for them.

May be - the last ones I saw recently on ebay were definitely above my budget.

Interesting what CSG tried out in an attempt to maintain market share.

Sorry for sounding off topic, but do anyone know if CSG ever opened a plant in a low labour cost country in order to try staying competive price wise?

I don't know the answer, but I read years ago in one of the industry magazines about a new plant set up in Texas IIRC to make memories, and there was heavy criticism for not doing it in another country where the labor rates were lower. The answer that came back was that labor was a very small part of the cost of making the memories, regardless of where you do it.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

I recall that as well. I also seem to recall that back in the 1980s, labor was only 8-10 percent of the "transfer cost" (cost to make the product, which does not including engineering, marketing, sales and service) of a typical chip design. Most of the cost was, and continues to be, in the physical plant, the machinery, processing of raw materials and disposal of the hazardous wastes that are part of chip-making. Much of the chip-making process these days is automated, mostly relegating human labor to non-manufacturing tasks. If anything, the cost of labor as a percentage of transfer cost is even lower now, at least outside of North America.

That main reason chip-making has all but disappeared from North America is the unfavorable regulatory climate, more-so in the USA than in Canada. In most other parts of the world, regulations are looser, hence the economics of a production scenario that uses a lot of hazardous materials are more favorable. It's an unfortunate reality and a constantly-shifting environment. Twenty-five years ago, quite a bit of this stuff was produced in the Republic of China (Taiwan). Taiwan subsequently tightened up their laws to head off emerging environmental problems, which drove up the investment and operating costs of chip-making plants, as well as the costs of industries that use chips. The "solution" was to move chip-making elsewhere, such as to Communist China.

This sort of geographical manufacturing chess game has gone on for a long time, beginning in the 1950s when the cost of union labor started to become an issue. It will continue for the foreseeable future.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

(Crossed the post with BDD's reply)

You'll commonly see chips of that era marked as "Philippines" "Mexico" "Portugal" - the fabrication, wafer test, packaging and final test are often done in different countries depending on supplier capacity and cost. (I wouldn't be surprised to learn that final test and bulk shipment to distributors are also separable.) Fabrication is the highest tech part of the operation, and is indeed very capital intensive. It also needs a skilled labour force, so the availability, rather than the cost, of staffing the fab might be an important factor. TI were always quite vertical, operating their own design and fabrication, and even building end-user devices such as calculators. Whereas say ST were a silicon outfit doing both design and fabrication, and ARM are a classic case of only doing design.

Ditto for WDC, who apparently was the very first fabless semiconductor house.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Just on the environmental headaches associated with semiconductor manufacturing.

I found the following interesting pdf on an old matter between the EPA and CSG:

http://webapp1.dlib.indiana.edu/virtual ... 301146.pdf