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32k expansion for the side port - released

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I want to be clear, this is a 32k ram expansion for the side port that replaces the need for 32k in a PEB or replaces the 32k internal ram mod correct?

 

No other bells whistles features or doodads right?

 

Correct.

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I may have gotten confused with several projects around here.

 

I want to be clear, this is a 32k ram expansion for the side port that replaces the need for 32k in a PEB or replaces the 32k internal ram mod correct?

 

No other bells whistles features or doodads right? An amazing accomplishment for sure, just trying to set my expectations properly, it can not; for instance, core a apple.

 

 

No doodads. If you have 32k in your PEB, you do not need this. I love PEBs. PEBs are awesome, I have 2. Everyone should have at least one. But they are a pain to buy and ship and take up a lot of space.

 

This memory board is targetting those that want their TI to stand on its own, without hacking on the insides, and to enable playing all the nice cartridge games that require 32k expansion ram.

 

[email protected]

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No doodads. If you have 32k in your PEB, you do not need this. I love PEBs. PEBs are awesome, I have 2. Everyone should have at least one. But they are a pain to buy and ship and take up a lot of space.

 

This memory board is targetting those that want their TI to stand on its own, without hacking on the insides, and to enable playing all the nice cartridge games that require 32k expansion ram.

 

[email protected]

 

 

You are going to fill a much needed gap.

 

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I may have gotten confused with several projects around here.

I want to be clear, this is a 32k ram expansion for the side port that replaces the need for 32k in a PEB or replaces the 32k internal ram mod correct?

No other bells whistles features or doodads right? An amazing accomplishment for sure, just trying to set my expectations properly, it can not; for instance, core a apple.

I'm sorry, if this doesn't core fruit, I'm out. :)

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I'm sorry, if this doesn't core fruit, I'm out. :)

Well, if you jam it into an OS X machine, it might create a core-dump ( or the Apple equivalent ) However, I'm not going to guarantee that behavior.

 

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This memory board is targetting those that want their TI to stand on its own, without hacking on the insides, and to enable playing all the nice cartridge games that require 32k expansion ram.

 

Yes, this is me 100%

 

I'm not against an internal mod, but for me a memory expansion that can easily be moved between TI's, this is the perfect solution.

Also, with the couple of TI's I have fixed recently, having an internal mod with wires going everywhere would make fixing / troubleshooting harder if the TI happens to die on me.

 

So please keep me in mind for a couple please :thumbsup:

 

Cheers,

Shane

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Have you got a schematic?

 

I started with the schematic for 32k PEB card from Thiery's TI Tech Pages.

Adapted it down for sideport ( removing only the concern of enabling the flex cable buffers, I believe? )

That schematic is much earlier in this thread.

 

Then I've been working on how much I can remove from that. The following is working as well as I can expect from a breadboard. I just need to tweak my pcboard layout a little bit and I'll go get a sample made.

 

32k-compact.pdf

 

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So, I want to write a memory test program because the ones I have ( Corcomp Diagnostics in the XB2.7 Suite ) and the one I've written already all pass, and that is not correct. :)

 

With my mess of jumper wires the breadboard prototype works, but it fails under certain programs... most obviously the parsec flashrom99 image that runs out of the 32k. Many other games work just fine, including things that undoubtedly run out of the 32k expansion such as the Mars Attack compiled basic program.

 

So, I want to produce a memory test that also exposes this. Any advice?

 

Note, I had similar issues with the earlier schematic on breadboard, and it works very well once solder is applied to a pcboard. So I have every reason to believe the same will be true once OSHpark ships me my board for the new compact schematic.

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I've always got by with basic memory tests - write a different value to each address in the first pass, then go back and see if you read the same values back. Doing it in two passes like that will catch mismapped address lines and stuck bits (shorted or open), which is most cases. For added fun you can do it twice, once straight up and once inverting the values, that way you test all the bits. There are more complex tests intended to catch less straight-forward or more intermittent issues, but even something this basic will catch a hell of a lot. I've used it numerous times on bringing up new hardware (some of it even shipped with the code still in there ;) ).

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I've always got by with basic memory tests - write a different value to each address in the first pass, then go back and see if you read the same values back. Doing it in two passes like that will catch mismapped address lines and stuck bits (shorted or open), which is most cases. For added fun you can do it twice, once straight up and once inverting the values, that way you test all the bits. There are more complex tests intended to catch less straight-forward or more intermittent issues, but even something this basic will catch a hell of a lot. I've used it numerous times on bringing up new hardware (some of it even shipped with the code still in there ;) ).

Thanks!

 

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I've got the revised / hopefully final / board out at OSHPark for initial samples.. went out last weekend. So I should be building the first 3 next weekend.
Which reminds me, I need to order dip sockets....

Man, how the time flies...

I'm still going with upright layout, and header instead of edge card pass thru.

I've worked up as good as I can get on this memory test ROM. It'll run out of FlashRom99, or earlier rom boards. It is just an 8k bin. Makes 10 passes at about 5 testing patterns against all of the 32k expansion memory.

-edited- ver 1.1 with some cosmetic tuneup: 32kexptest.bin

  • Final message doesn't write over screen footer.
  • Default screen is cyan (cause I like it)
  • Successful completion screen turns green.
  • version banner changed to 1.1

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Edited by jedimatt42
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This shall be added to my test toolbox as a physical cartridge. :) That way I can test with no hardware dependencies.

 

A dedicated cart would be nice.

 

I hate to use a bank switching board for something as little as this... Although I do have a black cartridge board I haven't found a use for yet.

 

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I build and test 40-50 cartridge boards of various types in a dedicated hobby weekend. Using one of those boards for a test cartridge actually saves on the overall labor required--although I could put the EPROM into one of the boards I have with an installed ZIF socket if I really needed to. . .but doing it as a dedicated cartridge also lets the boys run the tests for me. Muuuuaaaaaahhhh!

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Just a teaser - I received the sample boards yesterday (rev1) - waiting on components to populate it and test (hopefully that is what happens Saturday) before ordering parts in greater volume.

 

I already know of one issue, but I can revise that safely without a retest. The holes for the powerjack are too small. I'll machine some pins down to fit for testing, but make the holes larger for the rev2 board.

 

post-42954-0-63825000-1474573067_thumb.jpg

 

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Oh, and I've ordered 74hc chips to try... my earlier work has all been with 74ls chips... Stuart measured a current load much lower than I've been able to achieve, and I'm hoping this will work off the sideport power. There is a jumper for selecting the powerjack or internal power.

 

I'll measure and let us all know.

 

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Your board looks sweet and like that you screened the part numbers/values/orientation on it too. Really looking forward to this! Will be available to purchase in kit form as well? :love:

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Nice work. :) One other suggestion--you might want to make the holes for the mounting screws at the corners significantly larger as well. It will be a mighty skinny screw that fits through there now. . .

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Nice work. :) One other suggestion--you might want to make the holes for the mounting screws at the corners significantly larger as well. It will be a mighty skinny screw that fits through there now. . .

Yep, those looked so much bigger on my 40" monitor... I was surprised about how small they turned out... :) But I can grow the boundaries without any redesign :)

 

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Your board looks sweet and like that you screened the part numbers/values/orientation on it too. Really looking forward to this! Will be available to purchase in kit form as well? :love:

I hadn't thought about that... by kit form, you mean 'board plus components, assemble yourself?'

At this stage, I can only say I'll keep that in mind.

 

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Just a teaser - I received the sample boards yesterday...

 

gallery_35324_1027_100076.gif

 

Looks great so far. I agree with the Ksarul on the screw holes. It might make it easier to put in the 3D printed case that will obviously be made for it at some point.

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