Revisting Alex Freed Z80 Card

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Revisting Alex Freed Z80 Card

Greetings,

In the spirit of DIY retro cards, my build of Alex Freed design Z80. Mine runs at 18.4MHz using a CMOS 20MHz part.This build was from 2021. I had to create the CPLD image from the VHDL and schematic. Boards were made by JCLPCB.Initial comparison with the A2Pico Z80 CP/M emulation card, it is quite bit faster on the ASCIIART benchmark.
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Nice!  I was looking at

Nice!  I was looking at building one of those, but the CPLD kept me from it.  The Freed design I'd really like to build is his 6809 card.

 

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Do you have any spare Printed Circuit boards?

Do you have any spare Printed Circuit boards?

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Really cool stuff and thanks

Really cool stuff and thanks for sharing. I have an affinity for Z80 cards for sure.

 

I found this extremely valuable page the other day, a reference of various Z80 cards for Apple II, browsing about my own [cards]. Seems this one is included there, impressively. 

http://apple2.guidero.us/doku.php/mg_notes/cpm/cpm_combos

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I do have two unpopulated

I do have two unpopulated PCBs left.  Send me a PM if you're interestd in building one up.Cheers.

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Right,  there also was a

Right,  there also was a discussion on comp.sys years ago where Alex participated whilst working on this card.This particular  Z80-card design include on-board fast memory for  the Z80. This memory is also mapped into the Apple 2 memory space, so Prodos, for example,  have access to it if it so desire. Since the Z80 can operate without crossing the Apple memory barrier, it can really perform. Alex's 6809E-card design is nice also, however does not have the on-board memory. It would be possible to revisit that particular card if anyone is interestd in that. 

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