Some basic questions on cartridge pinouts

[unebonnevie]

Hi,

 

TI99/4A newbie! And looking to do my own cartridge. Please see http://www.hardwarebook.info/TI-99/4A_Cartridge_Port. I have some questions:

 

1) Differences between ROMG (pin 34) and GROM address range, pin 21? Pin 34 is where the cartridge code is going to be? GROM?

2) GROM ready, pin 35. What does it really mean?

3) The cartridge is read when pin 25 is HIGH and pin 34 go LOW?

3) What is "CRU" from pin 4?

 

Thank you!

[Stuart]

Hi, sounds like you need to familiarise yourself a little with the machine and processor architecture. You might want to take a look at [ftp://ftp.whtech.com/datasheets%20and%20manuals/Hardware/99-4A%20Console%20and%20peripheral%20Expansion%20System%20Technical%20Data.pdf] and [ftp://ftp.whtech.com/datasheets%20and%20manuals/Datasheets%20-%20TI/TMS9900_DataManual.pdf].

 

(In short, GROM is a type of memory accessed through a memory-mapped port, and CRU is a I/O interface unique to the TMS9900 family processors.)

[+Lee Stewart]

There's a lot of information on this forum that might take some digging on your part. Here are a few:

• Setting up a 512k cart
• Setting up a 632k cart
• UBERGrom boards now available on arcadeshopper.com
• Ideas for 512K carts
• 2048K Cartridge Board

Also, Thierry Nouspikel's site is a must read.

 

...lee

[Tursi]

Do read the above resources, but in short:

 

1) Differences between ROMG (pin 34) and GROM address range, pin 21? Pin 34 is where the cartridge code is going to be? GROM?

 

ROMG means a memory access at the cartridge ROM address (>6000 - >7FFF), and is meant to activate a ROM chip.

GS is GROM select, and means a memory access to the GROM device port (>9800 - >9FFF), and is meant to activate a GROM chip.

 

2) GROM ready, pin 35. What does it really mean?

 

This is an input pin from the GROM chip to the system. When GS is low, it is gated to the CPU HOLD line, and allows GROMs to delay the CPU until their data is ready. It is ignored during other cycles. This is necessary because GROMs are much slower than ROMs (more than 30 times so in my testing).

 

3) The cartridge is read when pin 25 is HIGH and pin 34 go LOW?

 

The ROM is, yes.

 

3) What is "CRU" from pin 4?

 

CRU is a single-bit addressable I/O system, in essence a third memory space (CPU memory, GROM memory, and CRU I/O). CRUCLK, CRUIN, A15/OUT, and A14 through A4 are involved.

[unebonnevie]

Thank you, all.

 

One more question: Is there EagleCAD part available for TI99/4A's cartridge?

[+Ksarul]

I do all of my cartridge boards using ExpressPCB or RobotRoom (and I'm the one who did the layouts for the circuit boards referred to in this thread as references).

[jdgabbard]

unebonnevie, I'm planning on doing a port of Ksarul's board over to eagle when I get a moment. I really just need to sit down and figure out the schematic and layout. Which might change with minor variations as far as the *.brd file is concerned. That would really help with the DIY guys like myself who would rather etch a board at the house than to order them from ExpressPCB or someone who did order them from the PCB house. Not to mention open up a few other places to order the boards which are far cheaper than ExpressPCB. However, if you decide to jump on that before I get a chance, feel free to PM me, and I'll help with testing the new board layout. I have all the stuff to etch and burn the EPROM. Not to mention a small hoard of components.

 

The schematic will be the hardest part, really. Not because it's a difficult schematic, but just because I've got to sit down and trace where all the traces go. I'm planning on doing that once I get done testing the PCB I'm building for a quad-bot I've got underway. Once that is tested I'll be getting it off to one of the pcb houses, and I'll plan on starting to work on the port to eagle.

[+Ksarul]

@jdgabbard, I use RobotRoom to convert all of my board files to standard Gerber format--so I can use pretty much any board house out there. What I haven't done is to release the designs (other than the 64K and 128Kx4 boards) for general purpose replication/use by anyone that wasn't part of the original design team. I do bulk purchases of them to ensure they remain available to the community--and will continue to do so for as long as there is community interest in them. That's a significant up-front investment--and risk. The sale price is usually sufficient to fund initial test production of the next item in my project queue (and there are about a dozen projects in there that haven't reached their position in the queue yet). I've put many thousands of dollars into my TI projects in the last few years--and a huge amount of time. Take all of the parts you need to have on hand to assemble and test new hardware and you understand the true scope of that risk, especially if you have taken the time to assemble your own etching rig. I've built at least five hundred boards for people now, at a much less than minimum wage return on the time I spent doing it--and all of which goes right back into the process to make more new things--and keep them available for as long as I can afford to do so. It is how I contribute to this community. If I copy a design from someone else--it is because I have their express permission to do so--and if I don't get that permission, the design never sees the light of day. I respect the hard work of those around me--and do my best to support the other half of the making community here, the programmers!

 

If you want to design your own hardware--no problem. I'll even provide the basic board templates properly sized/holed to fit into the cartridge case. I even have similar templates for PEB boards that I can provide. BTW, the RobotRoom files are also more than sufficient to produce the templates you need for etching your own boards--you can do that part without even getting their (inexpensive) paid license that allows conversion to Gerber formats.

[jdgabbard]

Ksarul, sorry man. I didn't mean to step on any toes. I had noticed you made the ExpressPCB file and the Gerbers available to the community, and had no intent to profit from it in any way. I knew you had various different projects that you had worked on, but also didn't realize that you did this as a means to fund future projects. My intent was to simply make it easy for the guys who are so inclined to have a at-home solution for a cart without reinventing the wheel. Simply make available what you had already done in a different format. Never to steal your idea or design, or profit from it for that matter. I don't use RobotRoom, and havent used ExpressPCB for the obvious reason (you're limited on what you can do with it). Similar to if this was done in, say, Fritzing. Some people use it. I don't because it doesn't suit my individual needs.

 

What I am saying is, I understand where your from coming from. And I do respect you and your work, reading about the work you guys have done has been a lot of fun. And if your wish is for this not to be converted into an Eagle *.brd file, I will withdraw my ambition. And I hope you'll accept my sincere apology. I just assumed with the files being posted on the forum that modifications were allowed as long as credit was given.

[+Ksarul]

As noted, the 64K and 128Kx4 boards (the two boards using 74LS379 switching) have been released to the community (although I also still do runs of the 128Kx4 boards at need, as have several other people). If you want to convert either of those to Eagle format, have at it. Also as noted, I'll provide template files to you too (they do come in handy when working on new projects), assuming you're interested in them. No offense taken (or intended, for that matter). My comments were more to outline what some knew already--but which I'd never explicitly stated before in one spot (going through all of the threads would give you the same answer--but in a very disjointed fashion). That's also why I mentioned RobotRoom as an option, since it will let you take those ExpressPCB layouts and output the masks you need for your own board etching--and that version of the program is free, so it saves you some of that reinventing the wheel time too. It took me about 10 minutes to figure out how to do just about everything I wanted to do with the program too, so it doesn't have a steep learning curve.

 

I started with ExpressPCB about 8 years ago, and migrated to RobotRoom because it would import and convert ExpressPCB files to the RobotRoom format--or straight to Gerber/Excellon. Not a bad deal for a program that costs $50. I still do my designs using ExpressPCB though, as I have built up an extensive library of custom components that meet my personal design needs. That's the primary reason I never went to Eagle--I was comfortable with the tool I had and I could easily get the output file to a format I wanted.

[unebonnevie]

@jdgabbard: Nothing wrong of converting the ExpressPCB files to EagleCAD, as long as the EagleCAD will open source like Ksarul@ did for his ExpressPCB release. Thank you!

 

Ksarul@, where can I check out/download your ExpressPCB design? Please consider giving jdgbbard@ permission.

 

I think I can do it on EagleCAD. Anyone knows what the spacing between pads for the TI cartridge? I guess I could open one and measure.

 

Thank you both!

Edited March 17, 2015 by unebonnevie

[+Ksarul]

Here's the most recent iteration of the 128Kx4 board, in ExpressPCB format. The spacing on the cartridge connector is .100 inches (or 2.54 mm if you're working in metric). This one makes board insertion easier by rounding the corners a bit, as well as doing a little bit of trace rearrangement. As already noted, this one can be freely used/modified.

 

I also have about 50 of the bare boards on hand and another 10 or so assembled boards for those who don't want to do their own boards.

ti_eprom_cart_512k_v4c.zip

[jdgabbard]

unebonnevie, I've already spoken with Ksarul off-thread. And he has expressed his permission to port it over to eagle. As for opening it with Eagle, eagle cannot open ExpressPCB files. So it is something that I'll have to do manually. Ksarul has even been generous enough to offer some templates for the PCB, which I may take him up on when I get my plate open enough to sit down and work on this. After having talked to him for a while through PM, I feel convinced that he and I would have EPIC nerd-out sessions if we ever found ourselves in proximity.

[Opry99er]

I'd been trying to find my old 16k boards I bought several years ago and can't find em. Any of these out there, or did the 64k replace the 16k on more recent bulk orders?

[+Ksarul]

Owen, the progression was

 

1. The 16K boards you have (using only one of the latches on the 74LS379 chip on your boards), which won't fit into a cartridge case if you use a socket for the 379.

2. The 64K boards from several runs (I think over 500 of these were made, all in all), using three of the latches on the 379 and the same 28-pin socket as the 16K boards--and I moved things around on these to ensure they fit into the case when the chips were socketed.

3. The 128Kx4 board (about 200 of these are in circulation now), which uses all four latches on the 379 and which has two optional switches to allow use of 32-pin chips up to 512K (these are the Black boards I sell and which are also available from the Arcadeshopper site). Any files/chips made for the earlier boards will work on these if the jumpers are set right.

4. 512K Red boards (about 400 of these boards exist, with about 300 of them in user hands--available from me or from Arcadeshopper), which use the 74LS378 to latch (this chip uses non-inverted outputs to latch, unlike the 379 which was set up to use the inverted latch bits for the first three boards). Because it is non-inverted, you would have to rebuild older cartridge images to make them work with this board. There are several unique images available for this board (Games 1, 2, 3, 4, 5, and 6; Utilities 1; Educational 1; and Jon's 512K Compilation of 8K ROM files). All but the compilation from Jon require a 32K card to work.

5. 2048K Yellow boards (I've only done 110 of these so far, with about 70 of those in user hands now), which extended the non-inverted bank switching scheme of the Red boards by changing to a 74LS377 and switching to 40 or 42 pin 8/16bit EPROMs. We only have two images for this one at the moment-2048K Games 1 (which contains the entire contents of the 512K Games 1-4 cartridges) and the Spaceballs Demo from Tursi. Any of the 512K images will also work on this board, and it would be possible to combine some of them into pairs (Games 1-2, Games 3-4, and Games 5-6) using 1024K chips to keep them appropriately themed (but those images would have to be built, as they don't exist yet).

6. The 8Kx4 Green Supercart board (40 of the 50 I made are in user hands) uses an E/A GROM and a 32K battery-backed RAM chip to make new supercarts on a board purpose-designed to replicate what was possible by mangling a Parsec cartridge board using the modification plans on the Mainbyte site. It is a lot easier to build this way--and it fits into a cartridge case with all chips socketed.

7. The Blue UberGROM boards. I've made 275 of these, with about 220 of those in user hands now. These multifunctional boards do a lot. They have 512K of Flash memory (not programmable in-system right now), using the non-inverted 378 method for bank switching (which makes them compatible with the existing 512K images). They also can have an Atmel1284P inserted into the 40-pin socket and be programmed to emulate up to 120K of GROM (in addition to the 512K of Flash ROM on the other chip) using the software Tursi wrote for it. It is true awesome sauce--and Gazoo has made several hard-coded images for it that exploit some of its advanced capabilities to make his XB 2.7, XB3, RXB 2012, and SEB images. It has a lot more capability too--Tursi went all out to make this a true Uber-chip, as his loader can program the Atmel in-system, it has the capability for bidirectional serial communication, A/D I/O and a lot more.

 

As you can see, lots of cartridge goodness!

[unebonnevie]

unebonnevie, I've already spoken with Ksarul off-thread. And he has expressed his permission to port it over to eagle. As for opening it with Eagle, eagle cannot open ExpressPCB files. So it is something that I'll have to do manually. Ksarul has even been generous enough to offer some templates for the PCB, which I may take him up on when I get my plate open enough to sit down and work on this. After having talked to him for a while through PM, I feel convinced that he and I would have EPIC nerd-out sessions if we ever found ourselves in proximity.

 

Sounds like a group hug is in order!

[unebonnevie]

Here's the most recent iteration of the 128Kx4 board, in ExpressPCB format. The spacing on the cartridge connector is .100 inches (or 2.54 mm if you're working in metric). This one makes board insertion easier by rounding the corners a bit, as well as doing a little bit of trace rearrangement. As already noted, this one can be freely used/modified.

 

I also have about 50 of the bare boards on hand and another 10 or so assembled boards for those who don't want to do their own boards.

 

Ksarul, I would like to buy one of the bare board. Please PM email where to send the money and how much. I assume there is no CPLD/GAL chips are needed in your 128Kx4 project? Haven't looked at the schematic you attached yet.

[+arcadeshopper]

 

Ksarul, I would like to buy one of the bare board. Please PM email where to send the money and how much. I assume there is no CPLD/GAL chips are needed in your 128Kx4 project? Haven't looked at the schematic you attached yet.

 

http://www.arcadeshopper.com/wp/?page_id=11#!/Hardware/c/12497083/offset=0&sort=nameAsc

[Opry99er]

Owen, the progression was

 

1. The 16K boards you have (using only one of the latches on the 74LS379 chip on your boards), which won't fit into a cartridge case if you use a socket for the 379.

2. The 64K boards from several runs (I think over 500 of these were made, all in all), using three of the latches on the 379 and the same 28-pin socket as the 16K boards--and I moved things around on these to ensure they fit into the case when the chips were socketed.

3. The 128Kx4 board (about 200 of these are in circulation now), which uses all four latches on the 379 and which has two optional switches to allow use of 32-pin chips up to 512K (these are the Black boards I sell and which are also available from the Arcadeshopper site). Any files/chips made for the earlier boards will work on these if the jumpers are set right.

4. 512K Red boards (about 400 of these boards exist, with about 300 of them in user hands--available from me or from Arcadeshopper), which use the 74LS378 to latch (this chip uses non-inverted outputs to latch, unlike the 379 which was set up to use the inverted latch bits for the first three boards). Because it is non-inverted, you would have to rebuild older cartridge images to make them work with this board. There are several unique images available for this board (Games 1, 2, 3, 4, 5, and 6; Utilities 1; Educational 1; and Jon's 512K Compilation of 8K ROM files). All but the compilation from Jon require a 32K card to work.

5. 2048K Yellow boards (I've only done 110 of these so far, with about 70 of those in user hands now), which extended the non-inverted bank switching scheme of the Red boards by changing to a 74LS377 and switching to 40 or 42 pin 8/16bit EPROMs. We only have two images for this one at the moment-2048K Games 1 (which contains the entire contents of the 512K Games 1-4 cartridges) and the Spaceballs Demo from Tursi. Any of the 512K images will also work on this board, and it would be possible to combine some of them into pairs (Games 1-2, Games 3-4, and Games 5-6) using 1024K chips to keep them appropriately themed (but those images would have to be built, as they don't exist yet).

6. The 8Kx4 Green Supercart board (40 of the 50 I made are in user hands) uses an E/A GROM and a 32K battery-backed RAM chip to make new supercarts on a board purpose-designed to replicate what was possible by mangling a Parsec cartridge board using the modification plans on the Mainbyte site. It is a lot easier to build this way--and it fits into a cartridge case with all chips socketed.

7. The Blue UberGROM boards. I've made 275 of these, with about 220 of those in user hands now. These multifunctional boards do a lot. They have 512K of Flash memory (not programmable in-system right now), using the non-inverted 378 method for bank switching (which makes them compatible with the existing 512K images). They also can have an Atmel1284P inserted into the 40-pin socket and be programmed to emulate up to 120K of GROM (in addition to the 512K of Flash ROM on the other chip) using the software Tursi wrote for it. It is true awesome sauce--and Gazoo has made several hard-coded images for it that exploit some of its advanced capabilities to make his XB 2.7, XB3, RXB 2012, and SEB images. It has a lot more capability too--Tursi went all out to make this a true Uber-chip, as his loader can program the Atmel in-system, it has the capability for bidirectional serial communication, A/D I/O and a lot more.

 

As you can see, lots of cartridge goodness!

 

Wow!!! Man, I need to start learning more about hardware, get a chip programmer or two and get to work!!!

 

You guys are killin' it!

 

Just got my 2.7 cart last week and I can't wait to plug it up and use it.

 

Need to find SOME PLACE in my little house to set up some TI gear...

 

Thanks for the rundown. It is cool to see the evolution like that... In a list.