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Z80MC rev.BD updates
I recently updated the Z80 Membership Card CPU card to rev.B, and the Front Panel card to rev.D. No big changes; but here are the improvements:
CPU rev.B The 5v regulator U8 has been flipped upside down, so its metal tab faces up (away from the board) instead of down (against the board). This improves its ability to dissipate heat if you're running with an unregulated 6-9vdc supply. I added a 6-pin power/serial connector P4. Its pinouts are the same as P4 on on the Front Panel, so a Sparkfun 5v USB-serial cable #9718 plugs right in. This connector is located in the same place as U8; so install one or the other (not both). If you are getting 5v power from the USB-serial cable, then you don't need the U8 regulator. P3 was added to jumper the serial input to the Z80 /INT input. This connection was made on the Front Panel; but with the P3 jumper, you can use the CPU board all by itself (no front panel). Use a serial terminal to talk to the monitor or run BASIC or other programs. Options were added to jumper bus P2 pin 28 to HALT or /BUSAK, and bus P2 pin 29 to /NMI or BUSRQ. This provides access to these pins if needed for your own accessory cards. Front Panel rev.D I replaced the hard-to-find LED-photoresistor coupler with a standard LED-phototransistor coupler. This required a new pulllup resistor, R2D. The optocouplers I bought seem to have a little too much gain. Some users have found that they can still hear the piezo when it should be off. My hearing isn't good enought to tell! If you hear it, try a lower value pullup for R2D, or replace the optocoupler with a lower-gain part. Forward into the past, Lee Hart -- There is a computer disease that anybody who works with computers knows about. It's very serious, and interferes completely with your work. The trouble with computers is that you 'play' with them! (Richard Feynman) -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com |
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Re: An idea!
timgreenowb via Groups.Io wrote:
Just joking. I forgot to put a smiley ? on my post. It's the chipWell, there are PDP-8 and PDP-11 clone kits (google PiDP-8 or PiDP-11). They use a Raspberry Pi as their "brain", which would fit in an Altoids tin. Almost *everything* has been put in an Altoid tin. I had a mad idea to put one of those tiny 12vdc-to-120vac inverters that plug into an auto accessory (cigarette lighter) socket in an Altoids tin, along with 12v worth of rechargeable batteries and a small PV panel. When the sun shines on it, you have a "nuclear power plant" in an Altoids tin. :-) Lee Hart -- There is a computer disease that anybody who works with computers knows about. It's very serious, and interferes completely with your work. The trouble with computers is that you 'play' with them! (Richard Feynman) -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com |
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Re: An idea!
timgreenowb via Groups.Io wrote:
Maybe Lee could do a J11 Membership Card next.I'm too "vintage", I guess. What's a J11? What do these two giant chips do? Josh and I have currently been working in the opposite direction. We've put an Altair 8800 in an Altoids tin. We call it the "Altaid 8800". :-) <> Lee80 Hart -- There is a computer disease that anybody who works with computers knows about. It's very serious, and interferes completely with your work. The trouble with computers is that you 'play' with them! (Richard Feynman) -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com |
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Re: Z80 Not Z8
From: bill rowe <bill_rowe_ottawa@...>
Sent: Oct 21, 2019 7:34 AMHi Charles and Bill, Yes, the Z8 is a different (later) Zilog microcomputer. The Z8 was built for smaller controller applications, similar to the Intel 8048-51 family. It has built-in RAM and ROM, and some on-chip I/O. The instruction set is completely different. I agree on changing the name of the group from Z8MC to Z80MC. Less confusing! Lee Hart -- Excellence does not require perfection. -- Henry James -- Lee A. Hart |
Lee Hart
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