Personal 4 port cartridge expansion project

[Sinphaltimus]

 

 

OK, I think it's time to start this topic. I almost have everything I need I think. First I want to copy and paste some important information from another thread () just to consolidate it here:

Tursi, on 05 Jan 2017 - 04:21 AM, said:

 

ROM Select and GROM Select should be enough. The problem with the Navarone Widget is it did NOT cut GROM Select. For some reason for the GROMs it cut the -5v, which the UberGROM doesn't use.

Sinphaltimus, on 09 Jan 2017 - 8:28 PM, said:

ROM Select? Maybe +5 and the GROM Select?

Tursi - "GS* (GROM Select) and ROMG* (ROM Gate).

Switching power isn't recommended, although you would need it if you get too many carts on there. (I have no idea how many too many is). The problem is that when you activate power to a chip, it likely won't be a clean transition and can cause the chip to malfunction."

 

Name I/O Use

- ---- --- -----------

1 RESET < Resets the system (active high)

2 GND Signal ground

3 D7 <> Data bus, bit 7 (least significant)

4 CRUCLK* > Inversion of TMS9900 CRUCLOCK pin

5 D6 <>

6 CRUIN < CRU input to TMS9900

7 D5 <>

8 A15 > Address bus, bit 15 / also CRU output bit

9 D4 <>

10 A13 >

11 D3 <>

12 A12 >

13 D2 <>

14 A11 >

15 D1 <>

16 A10 >

17 D0 <> Data bus, bit 0 (most significant)

18 A9 >

19 VCC +5 Volts power supply

20 A8 >

21 GS* > Grom select. Active low is addr in >9800-9FFF

22 A7 >

23 A14 > Address bus, bit 14. Select mode: low=data / high=addr

24 A3 >

25 DBIN > Active high = read memory

26 A6 >

27 GRC > GROM clock: color burst of VDP 9918A

28 A5 >

29 VDD -5 Volts power supply

30 A4 >

31 GR < Active high = GROM ready

32 WE* > Active low = write enable (derived from TMS9900 WE*)

33 VSS

34 ROMG* > Active low if addr in >6000-7FFF

35 GND

36 GND

 

 

Here's the idea I'm going with.

 

I'm going to mount an edge connector to a large board along with 4 cartridge ports. With 4 carts installed, you should just barely be able to slide a piece of paper between carts.

Lined up along one side will be an AV switch box with 4 buttons. The input AV output jacks will be shorted to complete the circuit. Basically, connect RCA plugs with their individual wires soldered together. This way I can splice the GS* (GROM Select) to left audio in and the ROMG* (ROM Gate) to right audio in per 4 inputs. Since I still have the ability to cut more lines (the video jack and the S-Video jack) per button, is there another cut you'd recommend? Like maybe the + &/or -5v? Or no?

 

The finished project will work by simply pressing the 1 button for cart 1 or 2 for cart 2 etc...

 

I'm not at all concerned with the ability to switch carts with the console powered on although it would be nice. That's why I'm wondering about cutting additional lines. Shutting the console off to switch is fine however. I'm really just looking to cut down the wear and tear on the cart port. The 4 cart expander will be connected to the console via cart expander cable. It's a personal project to solve a personal need at low cost. I will document it all with photos and text as I make progress sharing the experience and hopefully have a fully functional 4 port cart expander by the end. Remaining hopeful I will be able to start this coming weekend.

 

 

This is the exact switch box I plan to use.

 

Edited January 19, 2017 by Sinphaltimus

[Sinphaltimus]

Quick update. After some consultation, it appears I'll need to install some pull up resistors. (Thanks Tursi).

I've also concluded that it will require the console be turned off during the cartridge switch.

Next I have to order another GROM extension cable I think. I've been holding off. thinking I could figure something out to save on having to buy another but with my current setup, the existing one is too short. And I'm considering another option as opposed to 2 extension cables end to end.
Just creating an extension edge card straight through then length of the coffee warmer. But realistically, I think I'm going to dremel a hole in the bottom of the console and feed the extension down through that instead of up through the cartridge port.

This is stuff I don't figure out until I actually begin making it all. Sure there's some preplanning for the electronic stuff, but not so much for the cutting and gluing and things of that sort.

I hope to put together a quick mock up tomorrow just to help me visualize it in a few form factors.

[sjt]

If I'm understanding what you are doing.....you want to make a push button widget?

 

The push button part of your project is a bit of an over kill.

 

With support circuitry it would be possible to use a single push sw to select different cartridges.

 

Why not just make a board with daisy chained connectors and use a conventional slide switch along with a reset button.

You then switch cartridges and do a reset.... this works, Naverone sold a lot of them.

I think there is enough room for 4 cartridges. Not with advanced switching (4 position slide sw?)

[Sinphaltimus]

If I'm understanding what you are doing.....you want to make a push button widget?

 

The push button part of your project is a bit of an over kill.

 

With support circuitry it would be possible to use a single push sw to select different cartridges.

 

Why not just make a board with daisy chained connectors and use a conventional slide switch along with a reset button.

You then switch cartridges and do a reset.... this works, Naverone sold a lot of them.

I think there is enough room for 4 cartridges. Not with advanced switching (4 position slide sw?)

Because I have no idea what I'm doing and the more crazy it looks aesthetically speaking the more I'll love it.

 

Honestly, it seems like a relatively easy project compared to many other things and with the switch box already built, connecting lines and resistors "should" be a breeze. I'm going to work it ourr on paper this weekend. I really like the idea of the push buttons.

[sjt]

Enjoy!, have fun.

To help you, here are the details on how Navarone made the widget.

 

They used a 3 position double contact switch.

 

They switched the following lines:

 

One side of the switch, connected Rom Low to each of the different sockets 1-3

The other side of the switch, connected -5v to sockets 1-3 at the same time.

 

All pin 19 (Vdd +5) were connected to each socket through a 50K resistor.

All remaining pins are daisy chained to each socket.

 

The reset button connects GND to Vdd -5

 

The board I'm attaching a photo of was made sometime around 1984 or later in Hong Kong.

 

Parts list.

3- Leader EG-2540-36 Sockets

3- 50K resistors

1- Plastic button with carbonized insert (reset button)

1- Plastic slide sw with 2 seperate contacts

Misc: top and bottom covers, pcb, screws

 

That's all there is to it.

Edited January 19, 2017 by sjt

[Sinphaltimus]

Enjoy!, have fun.

To help you, here are the details on how Navarone made the widget.

 

They used a 3 position double contact switch.

 

They switched the following lines:

 

One side of the switch, connected Rom Low to each of the different sockets 1-3

The other side of the switch, connected -5v to sockets 1-3 at the same time.

 

All pin 19 (Vdd +5) were connected to each socket through a 50K resistor.

All remaining pins are daisy chained to each socket.

 

The reset button connects GND to Vdd -5

 

The board I'm attaching a photo of was made sometime around 1984 or later in Hong Kong.

 

Parts list.

3- Leader EG-2540-36 Sockets

3- 50K resistors

1- Plastic button with carbonized insert (reset button)

1- Plastic slide sw with 2 seperate contacts

Misc: top and bottom covers, pcb, screws

 

That's all there is to it.

Wow! Great resource! Thanks for sharing all of this!

[Sinphaltimus]

In a perfect world it will look as close to this as possible. I'm imperfect so we'll see how it goes.

Waiting on some more parts. I also have to go through my parts list and see if I have a 50k resistor.

What's the tolerance there? Would 47k suffice?

 

 

 

[+Ksarul]

Most resistors have a 10% tolerance factor, so 47K would probably work fine. The primary purpose of the resistor is to smooth out voltage spikes as you switch out the slots, so anything close will probably work great. . .

[sjt]

As Ksarul says ...just use 47K or resistors in series or parallel to get close.....

[Sinphaltimus]

So I did some more planning and practical examination and such today. I don't want to start the project without a schematic and I still have to desolder one of the GROM port adaptors to get the edge connector I need for the GROM port extension cable.

 

All the photos are here,

 

https://m.facebook.com/SExmortus/albums/10207984223395402/?notif_t=like&notif_id=1485029103485533&ref=m_notif

 

I'll share a few below...

 

 

 

Checking out minimum spacing.

 

With carts inserted.

 

 

 

All this nonsense I don't need.

 

 

So much more nonsense I don't need.

 

 

 

Now this I need!

 

 

 

Mock layout of how I hope things will go with a new board awaiting the dremel.

 

 

 

 

Edited January 22, 2017 by Sinphaltimus

[Sinphaltimus]

It hurt to do it but it had to be done. THANKS TURSI!

 

 

My final layout plans. Next, fit everything in to place then figure out wiring. I plan to use the board as much as possible but I imagine the board is strictly for holding everything in place and the rest will be all wired. I may use the board strictly for the cut lines and resistors. (ROM&GROM lines). And wire everything else.

Not sure yet. I have to see what it looks like on paper first.

[Tursi]

Don't even worry about it - there are so many of those floating around

[Sinphaltimus]

Don't even worry about it - there are so many of those floating around

It was painful. But I'm guessing there are more of these remaining than there are working consoles, that's what I kept telling myself.

[Tursi]

Sinphaltimus, on 23 Jan 2017 - 02:37 AM, said:

It was painful. But I'm guessing there are more of these remaining than there are working consoles, that's what I kept telling myself.

 

Well, I have hundreds.

 

 

And I know I'm not the only one.

[sparkdrummer]

Ive got close to that many, with a TI-99/4A wrapped around them.

[Omega-TI]

Hey Tursi, I don't have any cartridge port spares!! You hoarder! Want to sell me a couple at a fair price?

[+Ksarul]

I've got about a dozen loose ones, and a whole lot more with consoles wrapped around them. If you really want to make more than one of these, I can make you a small board design that you can use to make as many of them as you want. . .

[Sinphaltimus]

Hey Tursi, I don't have any cartridge port spares!! You hoarder! Want to sell me a couple at a fair price?

Tursi was very generous, I can reciprocate and send you some of the extras he sent me. Just pm me.

Edited January 23, 2017 by Sinphaltimus

[Tursi]

oh no you don't! This is MY hoard we're trying to clear out.

 

Send me your address Omega.

[Omega-TI]

oh no you don't! This is MY hoard we're trying to clear out.

 

Send me your address Omega.

 

PM Sent!

[Sinphaltimus]

So I cut the board tonight. Going to drill the screw holes this weekend AND I'm gonna have to drill connections for some part too since the holes are too small for the GROM ports and not at all aligned for the Switches. But that's OK, the baord is realy going to be used to just hold everything in place. Just about all the connections will be wired.

 

 

 

I'll also need to file down the cuts to fine tune them.

Edited January 24, 2017 by Sinphaltimus

[Sinphaltimus]

So I got to drill some holes this morning. I hope to get the grom port holes drilled out tomorrow morning...

 

 

 

 

[Meddler]

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!

[Sinphaltimus]

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!

Yep, but I also read elsewhere that is buggy with certain cartridges that way.

 

I wish I could find the source of that info or possibly someone can chime in to confirm or deny it.

 

I have two plans in place until I gain more clarity, the navarone way or the way Tursi suggests with 2 lines cut (neither one being the -5v).

 

I'm still a bit of a way from deciding. My short term goal is to build it first. Then wire it up. I'm hopeful I will have it built this weekend giving all next week to figure out the best way to wire it up.

 

I'm pretty sure these switches allow me to cut up to 3 lines per button if not more. Obviously less is desired but I want to do what will work with all carts, ubergroms and more.

Edited January 25, 2017 by Sinphaltimus

[Meddler]

Yep, but I also read elsewhere that is buggy with certain cartridges that way.

 

I wish I could find the source of that info or possibly someone can chime in to confirm or deny it.

 

I have two plans in place until I gain more clarity, the navarone way or the way Tursi suggests with 2 lines cut (neither one being the -5v).

 

I'm still a bit of a way from deciding. My short term goal is to build it first. Then wire it up. I'm hopeful I will have it built this weekend giving all next week to figure out the best way to wire it up.

 

I'm pretty sure these switches allow me to cut up to 3 lines per button if not more. Obviously less is desired but I want to do what will work with all carts, ubergroms and more.

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.

Edited January 25, 2017 by Meddler