The Mysterious APX-Z80BD-1

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This is kind of an odd one.

Recently while browsing around eBay, I ran across a vendor selling large quantities of Apple II compatible CP/M cards for $15.99 each. I already had an Advanced Logic Systems (ALS) Z-Engine card which works just fine, but I figured for the price it couldn’t hurt to grab another. Maybe I could even convince it to work with the IIgs!

The oddity started a couple of days after I’d made the “Buy It Now” purchase. I’d already received confirmation from the seller that the card had shipped. Out of the blue, eBay sends down a “SHMO Notice” advising me that the auction had violated eBay policy, had subsequently been removed, and I was “not required to complete the transaction”. Sure enough, all signs of the auction had been scrubbed from eBay’s database. Personally, I saw nothing in the auction’s description or content that looked out of place - other than a reasonable price for retro Z-80 card.

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Despite the doom and gloom, the card arrived this afternoon safe and sound. In addition to the card itself, it shipped with a three-page typewritten manual describing basic installation and use, titled “Z80 CP/M Board (APX-Z80BD-1)”. A quick search on Google for more APX-Z80BD-1 information or history yielded nothing.

The APX-Z80BD-1 could be a limited run, hobbyist produced card; there’s no obvious branding or marking other than a silkscreened “Z-80” label. It appears to be a well made, nearly identical clone of the Microsoft SoftCard in both layout and function. Most of the chips - including the Z-80 CPU - are manufactured by GoldStar, while the card itself is silkscreened as being made in Taiwan.

It also has an interesting row of four DIP switches which unfortunately aren’t documented in the supplied manual. I later found these to be a replica of the SoftCard’s DIP switches, and most likely have the following functions (from the Microsoft SoftCard Software & Hardware Details manual):

  • S1-1: Address offset (when off)
  • S1-2: Z80 DMA enable (when on)
  • S1-3: Non-mask int. (when on)
  • S1-4: Z80 interrupts (when on)

The normal operational setting for all four switches is ‘off’.

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Another hint that this may be a fan produced project is this entry from the final page of the documentation:

“A CP/M DOS is not included with your board, as this would raise the price of the board tremendously.

Should you find a need for the CP/M DOS, check with your local or a large Apple computer club library. Almost all clubs have a few, if not many, public domain CP/M diskettes that have the operating system on them.

The board you have just bought is MICROSOFT compatible. That means the normal CP/M programs that run on a normal Microsoft board will see and use your Z80 CP/M board as a replacement.”

But most importantly, does the card work? Absolutely! I installed the card in my Platinum IIe (using slot 4 as recommended in the manual), and booted Applied Engineering’s Apple CP/AM 4.1 successfully, just as with my current ALS Z-Engine. I was also able to get the card running on my IIgs as well, though I had to first set the system speed to “slow” in the Control Panel in order to boot CP/M without freezing.

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I’ve left the APX-Z80BD-1 in my IIe and installed the Z-Engine in my IIgs; the APX-Z80BD-1 is a lot longer than the Z-Engine and I worry that it might smack into the somewhat bulky TransWarp GS in slot 3 and short something out.

For a low cost, compatible CP/M card for the Apple II, you just can’t go wrong here. As mentioned previously, I’m not sure what the malfunction is with eBay, but Atlaz Computers does have them listed directly on their web site for $15.00 each if anyone’s looking for one.

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This page contains a single entry by nekonoko published on September 8, 2008 6:04 PM.

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