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Cromemco dazzler replica project

 
Gary C said:
I have put my rev C recreations on github.

Ansgar, are you going to do a rev D fork ?

github.com

GitHub - Gary-Clark/Cromemco-Dazzler

Contribute to Gary-Clark/Cromemco-Dazzler development by creating an account on GitHub.
github.com github.com
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Yes, I just checked out the Rev D changes on the second board. There are lots of changes in the routes, however only few in the schematics. I will probably create two versions, one with your Rev C design and all the "artwork" stuff, and the changes reflecting those in the Rev D schematics (i.e. minimal changes with respect to Rev C such as the R/C add-on), and another version with also all the changes in the routes of the actual Rev D layout. Risk is higher to introduce new bugs when doing all the changes in the routes, so it will be probably more safe to use the version with minimum changes.

I by the way have another finding, in the Rev D foils also the patent number was included, see attachment.
 

Attachments

  • Patent US4121283 Cromemco Dazzler.pdf
    1.7 MB · Views: 5
Hugo Holden said:
I think the crystal holes are likely ok for the crystal wires, but the pins on C17 are substantially larger I cannot recall the exact size probably 1mm to 1.3mm I would guess, you can check when you get the part and enlarge the holes accordingly. I'll see if I can find what I specified them at on my pcb. They cleared the pins on the original part.
Click to expand...

Got that capacitor in today, and yep you're right - I'm going to have to drill out those holes a bit. My calipers has the pin sized at about 1.05mm.

Question on this part, does orientation matter?
 
Gary C said:
I have put my rev C recreations on github.

Ansgar, are you going to do a rev D fork ?

github.com

GitHub - Gary-Clark/Cromemco-Dazzler

Contribute to Gary-Clark/Cromemco-Dazzler development by creating an account on GitHub.
github.com github.com
Click to expand...
@Gary C Updated PCB layouts for the Rev D boards are now available. I checked as good as possible, but probability is of course high there are still bugs. DRC reports still show lots of issues, some more than with your original drafts. I am not sure whether this has any impact on the production results.

Could not yet find out how to check connetivity between pads directly in the PCB editor anyway.

I have included the custom footprints and an updated version of the Futura font.

See https://github.com/akueckes/Cromemco-Dazzler-RevD for the fork.
 
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>>> Question on this part, does orientation matter?

It shouldn't do - it is a non-polarised device.

I have now got the majority of the dazzler library code disassembled. There are a few bits of 'code' that appear to still remain - but we are only talking about a few tens of bytes (if that). I suspect what I have left are data area(s) and (I suspect) data tables (e.g. for the character set).

I now have the task of trying to comment and make sense of what I have. Most of the code looks sensible (at the mnemonic level), but there are a couple of 'exciting' bits where lots of 8-bit registers are being moved around and manipulated.

Onwards...

Dave
 
the existing library code is was written in 8080.
If you take the existing published dazzler game code in the various manuals and a few of the disassembled code.
you can match up the library to where they locate in the demo game code provided.

beware some dazzler published code is not in fact cromemco dazzler code, that can be very confusion as example one site claims to have the disassembled code for spacewar when it is from a completely different machine hardware.

all the answers are sitting in the cromemco archive.
 
Getting close! Just missing 2 IC's that I somehow missed in the BOM and didn't order. First attempt at making the cable didn't go so well, ended up cracking the connector at both ends.. You really have to make sure you have good even pressure across the entire part as you crimp. 2nd attempt went much better and I'm happy with the results.

PXL_20240308_030646289~2.jpg

I had this little guy in my parts bin. If I drill out the OUT/+ hole a bit, I think it'll fit perfectly. Any reason I shouldn't use this for the video out? I think I'd rather use this than soldering the video cable directly to the board.
PXL_20240308_031917365~2.jpg
 
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nullvalue said:
Getting close! Just missing 2 IC's that I somehow missed in the BOM and didn't order. First attempt at making the cable didn't go so well, ended up cracking the connector at both ends.. You really have to make sure you have good even pressure across the entire part as you crimp. 2nd attempt went much better and I'm happy with the results.

View attachment 1275184

I had this little guy in my parts bin. If I drill out the OUT/+ hole a bit, I think it'll fit perfectly. Any reason I shouldn't use this for the video out? I think I'd rather use this than soldering the video cable directly to the board.
View attachment 1275185
Click to expand...


Oh dear,

I probably should have mentioned that creating the rainbow ribbon cable with the connector at each end is no mean feat. (I think I sent Daver2 a fully assembled connector & cable)

It is very important that when the parts of these connector plugs are pushed together, that it is done evenly and that the pins are not damaged. If it is uneven the connector will likely crack, or the connections will be poorly made.

It cannot be done properly without a tool for the task.

To this effect I made my own tool from a 1/2" thick piece of phenolic material.

The holes have to be deep enough to accommodate the pins on the connector. The holes are 2mm diameter on the tool I made. Then this tool is used to press the connector together in the vise so it is done evenly, without any damage to the connector, and it results in a proper connection to each of the wires in the Rainbow cable.

One way to mark out the holes for the Tool, is to use some 2.54mm grid pcb spot board as a template.

I am sorry I did not post this before.

Also, if you do use some type of video output connector, double check that it doesn't get in the way of any cards slides, that the boards slips into, in your particular computer.
 

Attachments

  • Con1.jpg
    Con1.jpg
    51.9 KB · Views: 4
Hugo Holden said:
I am sorry I did not post this before.
Click to expand...

But you did.. :) after I messed up my first attempt I actually went back and read what you had wrote (back on like page 8 or so). I had made other IDC ribbon cables before so thought these would be no big deal. I actually ended up using a small block of hard rubber. I used my broken connector to push into the rubber to create the holes, then put in the new socket and pressed with a vice - worked perfectly.
 
Hugo Holden said:
Also, if you do use some type of video output connector, double check that it doesn't get in the way of any cards slides, that the boards slips into, in your particular computer.
Click to expand...

Good call, and dang - so close. But with it positioned to come out of the side of card, with the composite cable plugged in it wouldn't fit in the Z-2D case. So I went rummaging again and found these which look almost identical to the connector used on hideehoo's original boards in post #284. I will just position mine to come out the top of the board.

PXL_20240308_153453395~2.jpg
 
It looks like the capacitors are all ceramic disks apart from C27 (56 pF). What type is C27? I have a ceramic disk capacitor.

Dave
 
Got my last part! put it all together, fired it up and ran GDEMO.COM and .... nothing!.. tried KSCOPE.COM and .... nothing again. darn.. black screen.

Sanity check: this is meant to plug into a standard composite video monitor right? So an AppleColor Composite or Commodore 1702 should work?

Guess it's time to go back through everything with a fine-tooth comb. The manual gives a test/tuning routine which relies on a front panel which I don't have. Was there any other diagnostics software?
 
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On a separate note, I wanted to share a few findings during my build, mostly just silkscreen issues:
  1. R1 says 80k, should be 30k
  2. R23 is on the board twice, one of them should be R24
  3. R26 position should be higher, next the part
  4. IC44 is mislabeled as 7404, should be 7474
  5. IC52 is mislabeled as 3408, should be 7408
 
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