Jump to content
Sinphaltimus

Personal 4 port cartridge expansion project

Recommended Posts

Hell! With those switches you can switch all lines! :)

 

The Great Doctor addresses the 'buggy' problem later in the upgrade article but this has nothing to do with the basic Navarone Widget.

 

p.s the Navarone Widget is so simplistic you might as well try it first.

http://www.ti99.com/ti/index.php?article89/cartridge-expander-navarone

again...Good Luck. ;)

 

Duly noted. Thank you.

Share this post


Link to post
Share on other sites

As you can imagine the Great Doctor has covered this (though, in his way, to expand) and tells us exactly what Naverone did in the first few paragraphs:

 

http://www.nouspikel.com/ti99/titechpages.htm

 

All chips are connected and powered except -5 is switched.

Too easy!

 

The problem is that boards based on the UberGROM fail when you switch the -5v for GROMs, because it doesn't use the -5V line. So the GROMs end up not getting switched out.

  • Like 1

Share this post


Link to post
Share on other sites

Tursi would be the authority on a UberGrom card and how it might react in a cartridge expander.

Maybe he can explain why it wouldn't work.

Edited by sjt

Share this post


Link to post
Share on other sites

Are you saying that supercarts and eprom cartridges don't work in the widget design? They do.

 

...not if there is an UberGROM board present.

 

...lee

Share this post


Link to post
Share on other sites

Are you saying that supercarts and eprom cartridges don't work in the widget design? They do.

 

Obviously you know better than I do. UberGROM emulation is clearly the same thing as Supercarts and Eprom carts. I'm pretty new to all this.

Share this post


Link to post
Share on other sites

Sarcasm, Tursi

I've been out of this for a while, (a few years) sorry I'm not familiar with AVR cartridge cards created to simulate groms.

I'm only familiar with eprom, supercarts and multicarts along with Gazoo created adaptations to run on them

 

Obviously you Do know better than I, since my assumption is you wrote the software that allows this grom emulation board to function....

 

Please explain further for those of us not around while this development was made.

 

Would a single Ubergrom cartridge work with others in a widget? or not.

Edited by sjt
  • Like 1

Share this post


Link to post
Share on other sites

I think it would be fair to say most, if not all of us have learned from Tursi over the years. To me Tursi is like one of those E.F. Hutton commercials from back in the day.

 

 

 

For people under the age of 50 that might not remember the E.F. Hutton commercials, I've attached one below for reference...

 

https://www.youtube.com/watch?v=2MXqb1a3Apg

Share this post


Link to post
Share on other sites

As Tursi already noted, The Widget drops the -5V line to switch cartridges--and the UberGROM doesn't care about that line, so the GROMs on it stay live, no matter what the switch position is. Any regular TI GROM cartridge will then fight with it for bus access, which is not good. I'm actually looking at an updated Widget board that will eliminate that problem, but it isn't too far along in my development queue right now. I'm watching the Sinphaltimus project with interest, as it may generate some ideas I can use too. . .

 

I have also seen some issues show up if more than two of the larger EPROM boards are in a Widget at the same time. That looks like it might be a power issue (three of them seem to load it down a bit too much), but I haven't tried to follow it to its conclusion yet. It doesn't always happen either, which is why I'm still playing with it. . .

Share this post


Link to post
Share on other sites

In keeping with Build It First then Wire It Up... I've made some progress today.

Drilling free hand...

16406689_10208047484856899_7800027518584

 

 

Spacing and board sie look good for internal mounting...

16265638_10208047512937601_2797843672604

 

 

From the rear showing a design modification. Grom edge connector is going to have to come out the center rear since I needed to reuse some a/v ports for structural integrity.

 

 

16406994_10208047521417813_6758333949194

 

 

Straight on view and you can see the screw holes at the A/V ports that were used to hold the original board in place. I decided to keep it that way.

 

 

16195886_10208047529338011_1226459410629

 

 

Topless...


16195243_10208047526697945_5319029508191

 

 

 

From the bottom...


16388328_10208047533298110_2498278978591

 

 

 

Scuffed up the cover (will repair and repaint when done) but....the dremel battery drains out. Need to recharge...


16387194_10208047544538391_6475429625513

 

 

TIFN...

Edited by Sinphaltimus
  • Like 2

Share this post


Link to post
Share on other sites

We first learned about the widget incompatibility about two years ago. Several of us spent about a month analyzing the issue and trying to come up with a board layout that would work with the Widget. My intent was to attempt to detect the -5v and switch the UG off if it went away. Unfortunately, due to the large number of components on the board and (probably at least in part) some inexperience with the analog side of things, not to mention the difficulty in reading a negative voltage from a positive microcontroller, we just couldn't get the detection to be reliable.

 

Two posts from back when we learned about it:

 

http://atariage.com/forums/topic/193163-512k-cartridge-status/?p=3019724
http://atariage.com/forums/topic/193163-512k-cartridge-status/?p=3053633

  • Like 2

Share this post


Link to post
Share on other sites

Rough cuts. The actual slots will need to be large enough for the cartridges since the cover is too thick. Next, I have to draw up an illustrative schematic to match so I will know how to write it up. Of course I'm going to submit it for peer review.

 

16402853_10208054602394833_4058652180643

 

 

 

And a shot of the rear. Once I get an approved schematic illustration I can start to wire it up....

16252516_10208054604314881_5460236266650

Edited by Sinphaltimus
  • Like 6

Share this post


Link to post
Share on other sites

Looking Good

Thanks. This was the fun part for me. The wiring is going to be fairly challenging once I figure it out.

Share this post


Link to post
Share on other sites

They say, "Imitation is the greatest form of flattery."

 

If this prototype of yours works out, there may be a market for a PCB, BOM list, and a 3D printed case. Just thinking ahead! ;)

  • Like 1

Share this post


Link to post
Share on other sites

OK. I think this is the way I gotta do it. Wadya think felluhs?

 

I believe this one is wrong - please see next diagram in following post.

post-47352-0-74562800-1486255656_thumb.png

Edited by Sinphaltimus

Share this post


Link to post
Share on other sites

OK I believe this one is correct. Please let me know -

.post-47352-0-50716500-1486292274_thumb.png

 

OK, I updated it.

post-47352-0-48939600-1486332868_thumb.png

Edited by Sinphaltimus

Share this post


Link to post
Share on other sites

I have to create a new schematic. Tursi described a different setup plus I need to study the supplied resources more.


I think this is how it goes...

post-47352-0-29908200-1487518913_thumb.png

 

 

Edited by Sinphaltimus

Share this post


Link to post
Share on other sites

Ok. Looks like the post above this is the Final schematic. I will start soldering this weekend.... Oh Joy!

Share this post


Link to post
Share on other sites

I got this far, then I started to solder, then I realized they were on the wrong side of the board. Then i desoldered it cleaned it up, now I'm back where I started. Taking the rest of the day off. Gonna go do other things while I work some stuff out for this project.

 

16997753_10208303736623033_1494123993812

  • Like 1

Share this post


Link to post
Share on other sites

I was finally able to get some prep work done. Will continue after work each day and hopefully get to wire it up soon.

Shif838 has been working on a multi cart switcher of his own and there appears to be an issue with the schematic so some alterations maybe needed.

I'll probably go with the standard Navarone wiring for 3 of the ports then reserve the last for the ubergrom. Each switch I am using allows for 4-6 lines (I forgot the exact number) to be cut at once so I will take advantage of that for the ubergrom port.

Right now I'm just tinning and soldering the splits from one (console port) to 4 (slots). I have 17 complete and the rest ready to solder together.


post-47352-0-63692300-1490610102_thumb.jpg

 

post-47352-0-05378000-1490610144_thumb.jpg

 

post-47352-0-11078800-1490610209_thumb.jpg

  • Like 4

Share this post


Link to post
Share on other sites

Wow, I always wanted a Navarone device, but after seeing that board (in post #5) I'm glad I never got one. They really took the cheap way out on that one!

 

Due to the number of wires, this project really needs a PCB (IMO), just to keep your sanity. Or wire-wrap (very fast, easy, and can last for years). Also, without looking at the 99/4A schematic, I would be leery about using a pull-up on the enables lines. One IC is all it takes to do the chip-select the right way, which would also allow you to change while powered-on (as long as you provide a reset).

  • Like 1

Share this post


Link to post
Share on other sites

My plan was to power off the console, switch, then power on. At least in this first iteration. But I'm interested in hearing more about this "Also, without looking at the 99/4A schematic, I would be leery about using a pull-up on the enables lines. One IC is all it takes to do the chip-select the right way, which would also allow you to change while powered-on (as long as you provide a reset)."

Share this post


Link to post
Share on other sites

Shift838 assembled a two port version and let me know he was having trouble with it. After a few back and forths, I built a quick and dirty one myself to troubleshoot. I got the same results - being that two cartridges would conflict and with one cart, it would work if selected and hang if not. After a little testing and thinking about it overnight, I realized that we need to add handling of the GROM Ready line to the circuit as well.

 

The inactive cartridge just needs GROM ready disconnected, so if you have 3 poles or more on your switch as Sinphaltimus does, it should be an easy fix. If you have only two poles like I do - I'm still thinking about whether that's possible. ;)

 

The problem is that GROMs are "not ready" by default and all GROMs link into the GROM Ready line. During a GROM cycle, the ready line is used to halt the 9900 until all GROMs go ready. Since the inactive cart doesn't see the GROM Select, it doesn't participate in the cycle and so stays "not ready" forever. The circuit as above works for ROM-only carts but needs this change to also support GROM.

 

I still need to test this theory, but it fits the symptoms and is pretty likely the cause.

 

post-12959-0-71305400-1490725170_thumb.jpg

Edited by Tursi
  • Like 2

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...