TI Mini Expansion System

[Artoj]

Hi All,

I just received my prototype board for the TI Mini Expansion System, it uses Peter Schuberts AT mini system cards from about 1986. I will post more info soon, here are some pics. Please note there are empty 40 pin sockets, these are there for adding a RP Pico or an ATMega 32, for future expansion. Regards Arto.

 

 

[Artoj]

Hi All,

Two more boards, first drafts. Regards Arto. 

[+Ksarul]

Two things on the SAMS board: the memory chips to make it into a 4096K board are really finicky (and seriously expensive new--over $120 each). That said, you might want to stay with the 512Kx8 chips for 1M. The other thing is the footprint on U16 looks like you used a .400 chip here, which is probably wrong unless you are using a really odd chip (.400 chips are not at all common).

 

It definitely looks interesting. . .

 

 

[Artoj]

Thank you Ksarul, I created the smaller version as well. U16 was fine it was a poor outline component I chose. Regards Arto.

 

[speccery]

Looks nice! What PCB design software do you use?

[Artoj]

Thanks speccery, I use EasyEDA at the moment, looking at using Kicad. As an Artist the interface is where the rubber hits the road,  I have used Diptrace for a few years, also Express PCB before that. Each has there niche design advantages. I started on AutoTrax and even made my own using Corel, so much good software now, I was even working on a TI99 version at one point, maybe when I make the V9938 card I might start programming in earnest. 

I hope to finalise my PCB work for the TI very soon, I am looking forward to making a TI card that interfaces with my Basic Ternary Computer design, one gate at a time, one computer function at a time. I am so amazed at the TI community, there are so many talented engineers and hobbyists. I would say without a doubt that the TI99 has proven to be a unique machine that seems to attract the most gifted. Regards Arto.    

[speccery]

Thanks @Artoj interesting to hear what people are using. I used to use eagle but have recently moved over to Kicad. I am still very much in the learning curve, but I have already created 6 PCB designs with it. Every single one has worked. Still kicking myself for not making the move earlier. But as you know, there's always a learning curve and each one of these programs has its own kinks. The nice thing about Kicad is that it's now so widely used that there's a lot of information available, as well as plenty of reference designs.

[Artoj]

Hi All,

First draft of the V9938 Card, based on the Mechatronics card, it has a Digitized Video input and VGA output. It uses the same flat cable as the Mech 80 card. Regards Arto 

 

[+Ksarul]

One note on the quirks of the Mechatronic design and the TI console: the console power up routines set a few VDP variables that have no meaning on a 9918/9929 system, but which have strange effects on the 9938/9958, as those settings mean something to the later chips. The console comes up with a black screen when entering BASIC. Easily reset (there is a program to do so in the Mechatronic manual), but a pain nonetheless. Not a reason to avoid this project, but it is some useful background data to help avoid confusion during project realization.

[speccery]

17 hours ago, Ksarul said:

One note on the quirks of the Mechatronic design and the TI console: the console power up routines set a few VDP variables that have no meaning on a 9918/9929 system, but which have strange effects on the 9938/9958, as those settings mean something to the later chips. The console comes up with a black screen when entering BASIC. Easily reset (there is a program to do so in the Mechatronic manual), but a pain nonetheless. Not a reason to avoid this project, but it is some useful background data to help avoid confusion during project realization.

Sorry to advertise my own project - but this is something which probably can be fixed with a TI-GROMmy board.

[Artoj]

Thanks Ksarul and speccery,

There is a momentary switch to enable the external interrupt(sets Low EXTINT Card Edge no 4) via a 74HC125A, to reengage the console from a blank screen and allow the V9938 to initialise. If that does not occur and you have no issues, turn off the console and then slide switch 2 of dip 2 to off, then all is OK. It all depends on which version of TI Console you have. The TI Basic sends VDP register codes while powering up that is not compatible with the V9938. In the future versions I hope to make this procedure redundant or speccery by his TI-GROMmy and could by pass these codes depending if the V9938 is on board. Regards Arto  

 

Dip SW2
S1: ON = NTSC. OFF = PAL
S2: ON = Button interrupt is allowed. OFF = button interrupt is not allowed. 
S3: ON = US ASCII. OFF = German Char Set

[Artoj]

Hi All,

Another first draft for the Mini card series, based on the Thierry Nouspikel IDE card. A few more cards (RS232, SD, USB, 48 bit IO , Ternary) should complete my work here before I start to work on some software, while I wait for lots of parts to arrive. Regards Arto. 

Edited January 17, 2023 by Artoj

[Artoj]

Version 2 Draft, I cleaned up a few connections and decided to use the BQ4802YDW, so I added a battery. Regards Arto.    

[Shift838]

20 hours ago, Artoj said:

Version 2 Draft, I cleaned up a few connections and decided to use the BQ4802YDW, so I added a battery. Regards Arto.    

 

you did put a 5k resistor between VSS and RST on the BQ4802 correct?  If not, the clock chip will not be detected.

 

 

[Artoj]

2 hours ago, Shift838 said:

you did put a 5k resistor between VSS and RST on the BQ4802 correct?  If not, the clock chip will not be detected.

Thanks, it was shown in the product sheet, it is now in draft v3. Regards Arto 

Edited January 19, 2023 by Artoj

[Artoj]

Hi All,

I am still sorting out my 3D printer, the heated bed has some issues, showing errors. So I have made the first draft of the STL files for the Mini Peb Box and Hard/Floppy Box. Regards Arto

  

[Archimedes5000]

Can you share this with me on KiCad?

axel.ahlborn@online.de

Greetings Axel

[Artoj]

12 hours ago, Archimedes5000 said:

Can you share this with me on KiCad?

axel.ahlborn@online.de

Greetings Axel

All the files will be made public when all the projects are finished and working. 80% are already available as schematics on this site. 20% is both mine and Peter Schuberts work, not in KiCad format yet. Waiting for lots of parts and boards, then testing, testing, testing and some programming. Regards Arto.  

[Archimedes5000]

Hi, sorry my mistake. I wanted to ask for TinkerCad because the pictures above look if you use TinkerCad. In TinkerCad you are able to share projects. Thats the Reason for my E-Mail Adresse above. My Tronxy x3s is a little bit older, but I am able to print 330x330x400 mm. Hope it should be enough for the STL Files. 

[Artoj]

46 minutes ago, Archimedes5000 said:

Hi, sorry my mistake. I wanted to ask for TinkerCad because the pictures above look if you use TinkerCad. In TinkerCad you are able to share projects. Thats the Reason for my E-Mail Adresse above. My Tronxy x3s is a little bit older, but I am able to print 330x330x400 mm. Hope it should be enough for the STL Files. 

Sure, I will share them, still I am not quite finished designing them. When I get the base board completed and at least one card made, I will go over the exact sizes, I want to make they sure all will fit nicely in the box. The lid has not been made yet, it will probably have an optional set of sockets for my Ternary expansion board. I was also considering adding a front area and a socket for future expansion as well.  I will email you soon when I have made some adjustments, regards Arto.   

[Artoj]

Hi All,

I am still waiting for many parts, in the meantime I added the Stuart Conner's TMS9995 SBC design including 32 I/O lines so it fits into the Mini Expansion unit. Now I can use the box without the TI99/4A connected via the side port. You can use Cortex Basic of the TMS9995 SBC from a terminal as it has a RS232 port, So now the box can fit a whole lot of cards that are built just for the SBC as well. I am still working on adding lots of CRU decoding as well, on a separate card that could possibly decode 128 and more lines. This should complete most of my projects for the TI99, one more card is still in the works. Regards Arto  

Edited February 7, 2023 by Artoj
fix number

[speccery]

5 hours ago, Artoj said:

Hi All,

I am still waiting for many parts, in the meantime I added the Stuart Conner's TMS9995 SBC design including 48 I/O lines so it fits into the Mini Expansion unit. Now I can use the box without the TI99/4A connected via the side port. You can use Cortex Basic of the TMS9995 SBC from a terminal as it has a RS232 port, So now the box can fit a whole lot of cards that are built just for the SBC as well. I am still working on adding lots of CRU decoding as well, on a separate card that could possibly decode 128 and more lines. This should complete most of my projects for the TI99, one more card is still in the works. Regards Arto  

That's very cool, thanks @Artoj! How many cards are you having now in total?

Now that I finally have a PEB (clone) myself, I've been thinking about a TMS9995 board for the PEB in the spirit of the Geneve, but that's another story. Is your board designed as a bus master, or can it co-exist when this is connected to the TI? Also, wondering if having a VDP card would be interesting too now that you have the CPU, for example my FPGA VDP design could easily be added in here...

[Artoj]

3 hours ago, speccery said:

That's very cool, thanks @Artoj! How many cards are you having now in total?

Now that I finally have a PEB (clone) myself, I've been thinking about a TMS9995 board for the PEB in the spirit of the Geneve, but that's another story. Is your board designed as a bus master, or can it co-exist when this is connected to the TI? Also, wondering if having a VDP card would be interesting too now that you have the CPU, for example my FPGA VDP design could easily be added in here...

The current design of the SBC is the bus master, still working out how to tackle all the timing and bus contention if I was to plug in the 99/4A, that will be worked out later. Yes the VDP card is vital, reworking another graphic card card to fit the V9938 that works with the SBC. Keyboard/mouse is another issue as well, that's why I put some 40 pins sets on the base board to get a pico to handle them but I just realised yesterday that I made a mistake on the pin spacing(subconsciously not wanting to use other brand chips), so 2 more TMS9901's can be used instead to handle keyboards etc. So the Mini Expansion Box has some options and the Mini cards may have to have more options. 

 

1st - the box can be used attached to the TI99 with - (all listed are within 80-95% done)

   Mini Expansion 80 Column Card

   Mini Expansion IDE Card 

   Mini Expansion FD Card  

   Mini Expansion RS232/Pio/32K Card (65%)

   Mini Expansion Sams Card

   Mini Expansion IDE Card

   Mini Expansion Sound Card

   Mini expansion SD/MIDI/I2C/SID/ADC DAC (20%)

Or

2nd - No Box and stacked on top of each other, with the one of lower cards attached to the side port, this way you can use the cards you really need  

 

3rd - No Ti99, use the Box separately with the TMS9995

   Mini TMS9995 SBC as master  (80%)

 These will have to be configured for the SBC

   Mini VDP card

   Mini IDE/FD/SD

   Mini Ram/SD/PIO/RS232-2

   Mini Key/Mouse etc

 

4th- Make hardware/software options so the Mini cards work on both systems.

 

I am enjoying myself rediscovering the TMS9900 and its families after not working on them for 30 years. I hope to create a tutorial on some of the design work. I can see all you TI guys are great at so many aspects and intricacies of the TI99/4A, it has made my journey one of gratitude for the shared knowledge. Thanks for all your encouragement. Regards Arto   

 

[Artoj]

One more...

 

5th - Use the SBC by itself with a Terminal and stack what other Mini Cards you need on top. You could even use the TI99 as the Terminal if you use the Mini RS232 card on the RH port. Regards Arto

[Artoj]

This is the last card (draft) of Peter's designs, I remember his card was not a genuine 2 way PIO port, as you can see did not use the TMS9901 chip. I will remedy this in another version as I have about 10 designs that use the PIO to control 2 way communication. I am having lots of delays on parts, so finalising all the cards might take some time. So in the mean time I will work on the 3d printed box. Regards Arto.