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32k expansion for the side port - released

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I have 44-pin Right Angle connectors. They are available (no need to cut down larger ones). The Percom expects to be the last item in the peripheral chain. IIRC, it also doesn't connect directly, it has a 44-pin edge connector like the console port. You use a cable with two 44-pin IDC socket connectors on it to link it to the TI.

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I was looking at the past from the future

gallery_35324_1027_58508.jpg

 

I stared at that connector for about 15 seconds, and in that time it felt like I was in the year 2019 thinking back on the last four years.

(Yeah, as I write this work of fiction it's late and I need to go to bed).

 

So what was the future like? Well, it has what is referred to as the Jed-EX or "Jedi Expansion System" created by: Matthew Splett.

 

Jed-EX (Jedi Expansion System)

 

Module #1 - 32K Memory Expansion

Module #2 - USB Interface

Module #3 - SD Storage Module

 

You see that little connector made it all possible. With the advent of the FlashROM 99, more people came back to the TI-99/4A and they all wanted an 'EASY UPGRADE' for the memory and Matt's 32K Memory card did just that at the end of 2016... it was under many Christmas trees. It was perfect timing!

 

Now, there is a human trait of always wanting more, and most of these new and returning TI'ers started commenting about 'how nice it would be to have a way to store stuff on their systems'. So Matt designed and built module #2, which was the USB interface that plugs into that side connector on module #1. Almost immediately people decided to 'go wireless' by plugging in these...

 

gallery_35324_1027_9909.jpg

 

So as you can see, 'Module #2' was a smash hit, everyone who had a 'Module #1' also bought a 'Module #2', and the excitement of the 'Module #2' sold even more TI consoles and more 'Module #1's' because now people could use the HDX program on their PC's or even use Stuart's Internet browser.

 

In 2018 Human nature struck again... now that people had an easy way to get information to their TI's, some wanted a dedicated storage device on the TI itself and just in time for Fest West 2019 Matt released the SD Storage Module, again it was a smash hit! Matt hit the TRIFECTA and the TI is more popular than ever. :thumbsup:

 

Oh yeah, the 3D printed case for this thing is also a work of beauty. The back is simple, openings for the dual USB ports and power connector. The top has a slit for the SD card and a hole the LED that plugs into the jumper Matt designed into 'Module #3'.

 

So now you know what the future of the TI looks like in 2019. Pretty cool huh? ;)

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Try a 74HCT245 (HC*T*). The logic levels for the HC range aren't directly compatible with the 74LS/TTL chips used everywhere else, but the HCT range is.

The HC*T* chip did the trick, for powering off the internal sideport +5v pin.

 

I measured 5-10mah, as the led flashed on and off. I find that low of a value astonishing, compared to the other chips. Luckily I employed trust-but-verify for this recommendation. So these are the chips I have on hand to build out the pcboards that are on order.

 

Thanks Stuart!

 

I need to hot-wire a spare speech synth, to pass the +5v through, and see if that provides enough juice.

 

[email protected]

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It the sideport does indeed provide enough juice to run the speech & my 32k board. At least empirically. I don't want to sever a connection so I can measure the load of the speech + 32k.. But the "parsec from FlashRom99" test worked well... speech and running the game out of the 32k ran without a hickup.

 

Here is a picture of what I did to the speech synth, and then I ran my board with the jumper set to 'TI'

 

Modified speech synthesizer (blue jumper wire across pin #1):

post-42954-0-75059800-1475474363_thumb.png

 

Anyway, since Stuart suggested I should be able to run with such lower current so many posts back, this has been a target. Oh, and to be clear, the boards that went to print have this option built in already. :)

 

[email protected]

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this is a dream device, it's as if it was designed for me i have a us /4a, speech unit, joysticks, dual tape leads, a load of carts and a flashrom 99 who hit the no 32k wall so this is absolute perfection.

 

i cant even begin to say how much i thank you for your work in doing this and i'm looking forward to when you open orders so i can purchase and finally put my /4a to the use it was intended.

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Bad news... I sent one out to Omega, and it fails that ridiculously intensive and thorough memory test, intermittently.

 

I actually have a batch I was going to give to Arcadeshopper today. But I will have to hold off and figure this out.

 

[email protected]

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I've been testing on multiple machines today. I get errors with or without external power... however I think there is something funky going on. When I switched the jumper to EXTernal, I accidentally forgot to plug in the power... but it STILL draws current from the TI. I don't think that is supposed to happen.

 

So I switched to an unmodified TI console and put an UNMODIFIED speech synthesizer inline in an attempt to isolate the power from the TI, guess what... it STILL draws power somehow from the TI. I dunno what's going on with this circuit, shared ground or what, but I wonder if some transient spikes coming from places it's not supposed to be may be the cause.

 

 

 

post-35324-25601_thumb.jpg

post-35324-0-44639800-1476488938_thumb.jpg

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It doesn't work at all when in that accidentally powered state. Or at least when I've done that it didn't. I think it only looks like it is on because of the LED circuit...

 

The memory test performs 5 pattern tests on each memory cell. While the spinner goes round, it is running all 5 of those patterns 10 times.

It then goes to the next bank, and does the same.

Then it loops back to the top and does that whole mess a total of 10 times.

So each memory cell is tested 150 times. Source code for this test is at: https://github.com/jedimatt42/ti994a-32kmemtest

 

I've made a tweak to my test program to loop 12 times per block, and 50 times across all blocks, so if it passes, it tests each sell 3000 times.

 

It has passed that. And then, I try again and it fails. It is a burnin test :)

 

The LED accounts for nearly half of the current used by the board, so I've tried reducing fluctuation by removing the transistor, and letting the LED be always on. Even then, I end up seeing visually that the LED pulses. It shouldn't in that state.

So, I've removed the resister that feeds the LED off the trace that feeds the chips. Leaving the LED disabled, and hopefully all of the power to the primary purpose of the board. That made it to round 30, and then failed.

Right now I'm attempting with secondary capacitor on the memory chip, and the LED circuit disabled.

 

Hopefully I'll have this corrected still before PRGE.

 

[email protected]

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