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  #21  
Old 04-12-2008, 01:08 AM
Grant Stockly Grant Stockly is offline
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Unicorn maintains a stock of any item on their website. They will sell you anything on there at that price. If they don't have it, they get it. They then will sell you one part.

They do not list 8008 microprocessors or Kenbak memory, but I have bought both. If you want a part they do not stock, then you have to buy a minimum of 25-100 parts.
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  #22  
Old 04-12-2008, 05:41 AM
sje sje is offline
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An early version of the Mac OS ran on a lightly modified Lisa; the product was called an Macintosh XL and included a hardware mod that changed the original oblong pixels to square pixels. Its 68000 ran at a blistering 5 MHz.

If you're serious about running a 68000 on an Altair bus, you might want to go with the somewhat castrated eight bit version of the chip, the 68008. Hard to find, though. Its address bus was cut from 24 to 20 bits while the data bus was cut in half from the original eight bits. I have a circuit for this, and let me tell you that you're going to have to hijack a few unused S-100 lines for getting the 68000 bus grant and DTACK scheme up and running. Also (and I may be wrong here, it's been a while), the 68008 was an NMOS design and had a minimum operating frequency requirement. Hopefully it is less than the 2 MHz upper limit of the rest of a typical S-1000 system.

I always had a fondness for the 68000 family, even though it really wasn't fully debugged until the 68030 (Integrated MMU) plus 68882 (FPU) combination. You see, I had learned Unix on a pdp-11/70 and the 68000 family is the logical 32 bit extension of the good parts of the pdp-11 CPU design. (Compare with the VAX-11 CPU that suffered a design by committee approach.)
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  #23  
Old 04-12-2008, 11:42 AM
Grant Stockly Grant Stockly is offline
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http://vt100.net/mirror/harte/Cromem...ual%201983.pdf

There are a few 68000 boards out there for the S-100 bus.

I would probably bring the excess memory addresses and specific processor timing out to a header to connect to a memory or ROM board.

The RAM seen to the MITS bus would either be a window or simply 0-64k. I/O addresses would have to be decoded some how...

Its not too much of a serious project, but its nice to think about.
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  #24  
Old 04-12-2008, 06:35 PM
sje sje is offline
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Cromemco was probably the last S-100 hold out. I remember them having significant advertising space in Byte magazine right up to the end of the S-100 era. The were some high hopes, mostly the hope that microcomputer class hardware could be sold at near minicomputer class prices. But it was not to be. And it wasn't too many more years until most minicomputer makers themselves were just footnotes in the bigger history.
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  #25  
Old 04-13-2008, 02:48 AM
sje sje is offline
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Default More on buses and cards

Here's an interesting manufacturer site: http://www.vectorelect.com/

They have hardware for sale for just about every bus for prototyping and other purposes. They even have three different S-100 prototyping boards. Alas, I have no idea about price and stocking details.

S-100 cards: http://www.vectorelect.com/Product/P...d/PBSTDBUS.htm

EuroCard selections: http://www.vectorelect.com/Product/Plugbord/PB3U.htm

These use a standard 96 pin and socket arrangement, and these seem to be popular among the European homebrew crowd. I believe this format was also used for Apple's NuBus implementation.
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  #26  
Old 04-24-2008, 03:11 PM
marty marty is offline
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Talking replicas

Hi Grant;
I have a cromeco s-100 card that has both a Z-80 and a 68000 on it, and it is an s-100 card...
THANKS Marty
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