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ralphb

Flash ROM Cart

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Tadaa!

 

post-35214-0-43105300-1460397847_thumb.jpgpost-35214-0-72107100-1460397856_thumb.jpgpost-35214-0-97279700-1460397864_thumb.jpg

 

My prototypes arrived, and surprisingly they worked on first try.

 

I do have a few spares. If you're interested in beta testing the board please send me a PM and I'll send you one for S&H. Note that this includes the board and instructions only, so you should be able to get parts, program an ATmega, and assemble the board on your own. If you don't have the tools and/or skills, PM me anyway and we'll see. But please: this is for people willing to test only!

 

Now the actual release will follow soon. I'd like to exchange the resistors' footprint and redo the silkscreen for improved clarity. On the software side, I need to add two missing features. Once that is done, everything will be released on GitHub so you can build your own cart.

 

If you don't have the tools (or patience) to build everything yourself, I'll be selling boards and probably assembled carts as well.

 

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Tadaa!

 

 

56388698.jpg

 

That is bloody beautiful!

 

I know you questioned in the past if it would fit in a standard cartridge, it looks pretty close from the photo. Maybe just a little Dremel action for the SD card?

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That will not fit in a standard cartridge case, Omega. You'd have to solder the chips closest to the cartridge port in without sockets, and the other chips will have some potential positioning issues too, based on my experiences with the other cartridge boards. It would be a good idea to design a new case and 3D print one to make some molds--then you could build more of them in cased mode. These would be a good candidate for that process, as they would never need as many cases as we use for regular cartridges today. . .so the type of low-volume production possible with molds would work well.

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RalphB, this is truly impressive. So you are both a great software developer XGA99 (cross dev tools) and a great hardware guy. I am not sure how far off the current circuit is to be able to emulate GROMS similar to what UBERGROM, but so far I think this is a must for any TI collector. Kudos and keep up the great work.

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About the dimensions: It's 10 cm wide (standard) and 8 cm long, about 1 cm longer than a standard cart. And it doesn't have the hole in the middle.

 

For the board in the picture I socketed the 541s towards the connector, which makes the cart a really tight fit in the cart port. There's less than a mm head room between the top of the ICs and the plastic frame of the cart port. For any kind of case, sockets are a no-go. No big deal, though; the only thing worth socketing is the big 8515.

 

And of course cases need openings for the LED, the reset button, and the SD slot.

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Since January I've been working on a new project: the Flash ROM Cart. As the name suggests, the cart allows playing ROM images stored on an SD card on an unexpanded TI 99/4A.
The cart works with individual ROM banks, e.g. from RPK archives, or single non-inverted images. In the video I'm inverting an inverted image to get a non-inverted one. (For some reason the screen capture comes out quite blurry, but fullscreen is OK.) The current board uses a 32K RAM chip, so images are limited to that size. No GROMs, sorry.
I'm using an ATmega 8515 to read data from the SD card and fill the SRAM chip. Bank switching uses the well-known design by Jon, this time with a 377, as those are still commonly available. The 377 is also used for one-way communication from the TI to the cart, i.e., the image selection.
Alas, those parts alone won't do. In order for the microcontroller to access the RAM, the RAM needs to be isolated from the TI 99 bus. I thus added three 541 chips that will take the entire cart "offline" when the ATmega is active. This makes it unlikely to fit into a regular TI cart case, but I couldn't come up with a simpler design without resorting to SMD parts.
As you can see, this is a prototype. This even started on a breadboard with an Arduino, but I soon grew out of that. I'll do a layout and get proper boards made next. Once I have that I'll publish everything up on GitHub so that other people can get their hands on it.

 

RalphB. For such a project to emulate GROMs. Would the same circuit be adequate and it's only software emulation that is required ? Thanks.

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No, unfortunately, adding GROM support is not simple at all. In fact, it would be much simpler to add an SD card to the UberGrom than to add GROMs to the FlashROM. This is a guesstimate, though, as I've never looked at the design of an UberGrom -- on purpose, since I don't want to spoil the learning and discovery fun for me.

 

If I ever do GROM, it will probably not be an extension, but a different design.

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I can see that there will be a need for at least one utility program for this little gadget right off the bat....

As it stands now, there are people out there who have P-Boxes, without RS-232 cards, or an HxC or any other way to get NEW games or programs to "Real Irom". This thing could solve that problem VERY EASILY. If it can get it's own little disk manager, or if a program like DM2K gets updated to support this... wow.

I wonder how many people with unmodified P-Boxes with the original 5.25" drives are just sitting out there unused. This thing will give those people a viable option, hopefully at a decent price. Once they get back in and hooked....

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I can see that there will be a need for at least one utility program for this little gadget right off the bat....

As it stands now, there are people out there who have P-Boxes, without RS-232 cards, or an HxC or any other way to get NEW games or programs to "Real Irom". This thing could solve that problem VERY EASILY. If it can get it's own little disk manager, or if a program like DM2K gets updated to support this... wow.

 

I wonder how many people with unmodified P-Boxes with the original 5.25" drives are just sitting out there unused. This thing will give those people a viable option, hopefully at a decent price. Once they get back in and hooked....

 

Are you thinking of a PC side tool that would pack up disk files as some kind of self-extracting cartridge images? That might work, but the 32K limit would be annoying.

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Actually I was just thinking of a small program that would reside in the cartridge that would work on the TI-side to take the files from the cartridge so they could be put onto a diskette.

 

If 32K is the limit, then it would be more like 24K with a small transfer program installed. I agree it might be a tad inconvenient to have to do a couple of swaps to get a multi-part (32K) program over, but with no other options, I doubt there would be too many complaints.

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Actually I was just thinking of a small program that would reside in the cartridge that would work on the TI-side to take the files from the cartridge so they could be put onto a diskette.

 

If 32K is the limit, then it would be more like 24K with a small transfer program installed. I agree it might be a tad inconvenient to have to do a couple of swaps to get a multi-part (32K) program over, but with no other options, I doubt there would be too many complaints.

 

I suppose such a program could be designed any number of ways; but, it would need to manage buffer space in VRAM (much less than 32KiB) for the DSR(s) on the disk controller(s). Most disk controllers need a VRAM record/sector buffer. This buffer might be anywhere from 1 record to multiple 256-byte sectors in size.

 

Obviously writing the DSR for the cartridge's SD card would be the hard part. The unfortunate circumstance here is that the DSR would need to be in GROM (written in GPL) for it to work in a cartridge and that would require invocation of console GROM0's DSRLNK, which is what Millers Graphics’ DSRLNK (used by fbForth 2.0) does.

 

I suppose we could write a DSR for one of the cartridge ROM banks; but, we would also have to write our own DSRLNK that would add a search of cartridge ROM headers to the usual searches of peripheral ROM headers and, possibly, GROM headers. It might be fun. Has anyone ever tried such a thing?

 

...lee

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I can see that there will be a need for at least one utility program for this little gadget right off the bat....

As it stands now, there are people out there who have P-Boxes, without RS-232 cards, or an HxC or any other way to get NEW games or programs to "Real Irom". This thing could solve that problem VERY EASILY. If it can get it's own little disk manager, or if a program like DM2K gets updated to support this... wow.

 

I wonder how many people with unmodified P-Boxes with the original 5.25" drives are just sitting out there unused. This thing will give those people a viable option, hopefully at a decent price. Once they get back in and hooked....

Minor quibble: if they've got a PEB with 5.25" drives, then they have a PEB with a disk controller. If they have a PEB with a disk controller, then they can just as easily install a HxC and call it a day.

 

I don't see how *this* SDCARD cartridge would solve *their* problem. If they're unwilling to pony up for an HxC, I don't see why they'd pony up for a cartridge-port program transfer solution.

 

The SDCARD project is just fine for what it's intended for -- an easily swappable ROM-at->6000 multicart. If we're talking about turning it into yet another way to transfer programs from PC to TI, might as well start with the UART built in to the UberGROM.

 

Just my two yen.

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The beauty of this (and all the other things people are developing) is that people actually have a choice now. This one, the GROM one under development, the ROM boards, UberGROM, the HxC, the HDX via RS232, etc, people can kind of pick what works best for them. Rewind five+ years, and we only really had the ROM cartridge board under development. This community never ceases to amaze me with the amount of people diving in and doing stuff like all these new projects. :)

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I still laugh at a conversation I had with another of my TI friends back around 2000 or so. His comment was that the entire cartridge thing was old hat--and that nothing new could come out of there anymore, especially when one considered all of the nice GRAM devices that were available. Those GRAM devices are, unfortunately, hard to find now--but those "worthless" cartridges live on and flourish. :)

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Oh, no, please don't misunderstand. I myself was borderline flabbergasted when I found that the TI still had a thriving community when I was gifted a few consoles last year, and I'm extremely impressed with Jim and Mike's work on things like the UberGROM. The TI overcame its implementation inadequacies, in part, due to a userbase that recognized what it was capable of and had the skills to build the gear.

 

What Ralph has put together is wonderful. It's a cartridge that acts like a ROM-only multicart, putting together a menu at boot time based on what it sees on the SD card. It's neat.

 

What it isn't and shouldn't be, though, is a file-transfer tool. There's an old engineering adage: "the device shall do one thing, and shall do it well". (The UberGROM defies that a little bit, but it's okay, because it already works icon_smile.gif )

 

So when I see things like post 42, my hackles raise a bit. Not just because it defies the adage in the above paragraph, but because it's volunteering Ralph for work that wasn't part of the personal itch that he was scratching.

 

In my opinion, that's not okay. There are a number of pre-existing and currently-obtainable gear that will accomplish, with greater ease, the ideas put forth in post 42 under the conditions stated in post 42. And, hell, if an "ideas guy" wants to learn how to program and transfer files from a PC to a TI via the cartridge port, there's already a reasonably-priced UberGROM that has that exact functionality built in. All that's missing is the software ... but software's easy, right, guys?

 

That's what I was trying to say last night, anyway. No disrespect intended to anyone, and lots of respect (and a bit of protectionism) directed towards Ralph.

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