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TI(ny)-99/4A Computer


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Thank you all ! :-)

That's done, the PCB is finalized. These last days, I worked on the optimization of the 4 layers routing, the density of the components (see below) prevent any automatic PCB routers to work well, so I had to manually re-work an important part of the traces design.

 

tiny994a_v2-comp2.gif

 

Maybe, wou have noticed a little logo near the name of the computer, it's a piece of coal. Souvenirs... :-)

Updated picture of the motherboard (v2.6): http://www.ti99.com/ti/data/images/tiny994a/tiny994av26.jpg

 

The official web page: http://www.ti99.com/ti/index.php?article138/tiny-99-4a-v2

Edited by fabrice montupet
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  • 1 month later...

Thank you :-)

Yes, 4 layers. The PCB is finalized since several weeks, as I had to do some expenses (nothing to do with the retro computing) I also differed the PCB production by some weeks. I used (and use again) this waiting time to optimize the routing of each layers. It's a funny brain teaser. The layers are defined as follows:

- Signal/power

- GND

- Signal

- Signal/power

 

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Thinking... What about making the PCB of the TiNY fit in a ATX tower!

Would be cool to have the "normal" tower for the TI and the then the space is not problem and there is a standard to make the electronic fit.

BUT, I love what your doing!

It looks so clean and... ohhh shit so desirable :P

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Thank you :-)

 

The PCB had to have screw holes, so I thought that as long as I place holes, I should place then respecting a standard. And ATX is the most common.

After that, the futurs acquirers will do as they like: Create their own case, use a Mini ATX case, use a modified PEB case or anything else :-)

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  • 2 months later...

Thank you :-)

 

The PCB had to have screw holes, so I thought that as long as I place holes, I should place then respecting a standard. And ATX is the most common.

After that, the futurs acquirers will do as they like: Create their own case, use a Mini ATX case, use a modified PEB case or anything else :-)

 

Fabrice,

 

What is the status of this project? Will you be offering sales for interested individuals? Hopefully assembled?

 

Thanks for any feedback.

Beery

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The Tiny-99/4A v2 is finalised since some days :-)
I'm working on realisation of the PCB of the extended keyboard. Currently, I use the computer with my prototype keyboard (the one of the TIny-99/4A v1.0)

I would love to integrate the TIM VDP (I dream to own one) but I don't have the schematics and the code of it. In any case, I must have to creator's authorization.

Edited by fabrice montupet
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The Tiny-99/4A v2 reacts as the original TI-99/4A, so it can receive a TIM device or a SAMS card.
For SAMS installation, I added a jumper to disable the onboard 32Kb expansion. At a time, I considered the integration of the SAMS device on the PCB but I made the choice a tiny PCB and there is already a very concentrated population of ICs on it (It's the reason why the PCB has 4 layers). Adding the SAMS would have increase the size of the board. But as the computer has 3 expansion slots, I said to myself that it was always possible to install the SAMS board if necessery. This is why I added the jumper to disable the onboard 32K RAM.

The computer integrates a extented 32 Kb ROM, it's a user ROM, so it can contains what one wants. (Currently, the v2 that I use contains Editor/Assembler II r2). This extra ROM is automaticly disable when a cartridge is plugged to prevent conflics.
There is a special case: To be compatible with the FinalGROM, I had to add jumpers that disable the extra ROM. This is not a real limitation because if someone has the FinalGROM, this 32Kb extra ROM has less interest.

The Tiny-99/4A v2 integrates a RTC based on the MM58167. So it will conflicts with the clock feature of the PGRAM. I haven't considered to disable the RTC on my computer, so there's no jumper. It's not a choice but a forgetting (whoops!) , But the traces of the control lines of the MM58167 are on the top and bottom layers of the 4 layers PCB. So, it's easy to disable the onboard RTC.

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The Tiny-99/4A v2 reacts as the original TI-99/4A, so it can receive a TIM device or a SAMS card.

For SAMS installation, I added a jumper to disable the onboard 32Kb expansion. At a time, I considered the integration of the SAMS device on the PCB but I made the choice a tiny PCB and there is already a very concentrated population of ICs on it (It's the reason why the PCB has 4 layers). Adding the SAMS would have increase the size of the board. But as the computer has 3 expansion slots, I said to myself that it was always possible to install the SAMS board if necessery. This is why I added the jumper to disable the onboard 32K RAM.

 

The computer integrates a extented 32 Kb ROM, it's a user ROM, so it can contains what one wants. (Currently, the v2 that I use contains Editor/Assembler II r2). This extra ROM is automaticly disable when a cartridge is plugged to prevent conflics.

There is a special case: To be compatible with the FinalGROM, I had to add jumpers that disable the extra ROM. This is not a real limitation because if someone has the FinalGROM, this 32Kb extra ROM has less interest.

 

The Tiny-99/4A v2 integrates a RTC based on the MM58167. So it will conflicts with the clock feature of the PGRAM. I haven't considered to disable the RTC on my computer, so there's no jumper. It's not a choice but a forgetting (whoops!) , But the traces of the control lines of the MM58167 are on the top and bottom layers of the 4 layers PCB. So, it's easy to disable the onboard RTC.

 

Well like a REAL IRON TI99/4A I would like what I had originally:

 

SAMS, TIM and ability to write and load plus test GPL.

With this hardware I could make RXB into a 80 column in Editor mode, pump up the graphics to 4 times the number of pixels as 9918

and make good use of 1 or 4 or even 16 meg of SAMS RAM.

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  • 1 month later...

While the Tiny99/4A v2 computer is finalized, I get a sense of uncertainty about two onboard features:
- The 32Kb ROM expansion (that can contain user programs as Editor/Assembler, Disks manager or anything else) This ROM is automatically disable when a cartridge is plugged.
- The 32kb expansion RAM
I notice that fhe first feature has less interest since the recently arrival of the excellent FinalGROM.
I wonder if the second feature is enough for the newer software.

Maybe, my doubts are unjustified? In fact, I am thinking about a feature that could replace the ROM/RAM expansion with the SAMS, maybe more useful. But before, I have to ask two questions:
- What a SAMS 1MB/4MB feature support would bring today, in 2018?
- Will the SAMS be substantially used in newer software?

The removing all the circuitry of the two actual features is not quite enough to leave room for the SAMS one. The components integration of the motherboard is already a lot condensed but I think that I will be able to load the additional components. A solution would be to add a special slot for the memory banks. The low profile memory card could support 1MB or 4MB configuration).

Should I maintain the computer in its actual stage? Should I modify it to integrate SAMS? What is your point of view about it?
Thank you :-)

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