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Chefgon

32k Sidecar

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I'm assembling my first TI-99 system and I was hoping to use an original Texas Instruments Memory Expansion sidecar but I'm not sure how rare they are. How often do these show up for sale? Should I give up now and buy a modern alternative or keep checking until one shows up on the market?

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Personally I'd give up now. Why?

 

1) They take up a lot of desk space and are usually a little banged up looking.

2) They are old, so chances are higher that they will stop working sooner than new tech.

3) The price you'll pay for an old one is probably higher than a new one.

4) If you want to expand later (like with a TIPI), you'll have to get a new one anyway.

 

So... why waste your money on an old one? Keep your future expansion options open, buy the Jedimatt42 version from arcade shopper

<< BY CLICKING HERE >> and save the time and the hassle of trying to find an old clunky beater.

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An option would be to get a PEB. That way you keep the stock look and have modern options installed as well such as the TIPI and SAMS boards. It may be that it ends up not being that much more than an original sidecar.

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Posted (edited)

Okay, follow-up question. I already have a Disk Controller sidecar, will Jedimatt's memory expansion work with that? Can it be added after the disk controller in the chain, or can its TIPI expansion interface be converted to a standard pass-through port?

 

For clarity, I currently have no intention of using a TIPI. Outside of maybe a Lotharek my intent is to keep the system as original as possible.

Edited by Chefgon

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I don't know if it passes power down the chain, but if not, I think it'll still work at the end if you power the 32K separately.

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Okay, follow-up question. I already have a Disk Controller sidecar, will Jedimatt's memory expansion work with that? Can it be added after the disk controller in the chain, or can its TIPI expansion interface be converted to a standard pass-through port?

 

For clarity, I currently have no intention of using a TIPI. Outside of maybe a Lotharek my intent is to keep the system as original as possible.

I don't believe the DC passes it down, I think it has to be last in the chain, but I could be wrong.

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Posted (edited)

I don't believe the DC passes it down, I think it has to be last in the chain, but I could be wrong.

 

I've heard that the Disk Controller has to be last in the chain, but I find it odd that it has a pass-through port on the side if nothing will work in it. But then I've also heard that the 32k has to be first in the chain (or second after the speech synthesizer) so it seems there are multiple possible rules working against me.

 

If both of those rules are power-related, maybe the external power supply with Jedimatt's device would solve the problem and let me put it after the Disk Controller? I don't understand the nature of these rules well enough to know about workarounds.

Edited by Chefgon

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A complete TI sidecar expansion required the Speech Synthesizer first, the 32K memory expansion unit second, and then the rest of the devices can be in any order (according to the manuals). Originally, only 3 devices in series were supported, but something in the 32K unit allowed for 3 units to be placed in series after it, increasing the amount of devices that could be connected.

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Okay, follow-up question. I already have a Disk Controller sidecar, will Jedimatt's memory expansion work with that? Can it be added after the disk controller in the chain, or can its TIPI expansion interface be converted to a standard pass-through port?

 

For clarity, I currently have no intention of using a TIPI. Outside of maybe a Lotharek my intent is to keep the system as original as possible.

 

The connectors are physically incompatible.

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the 32k side car has a PIN connection to the right of it, so it will have to go on the end.. I have one set up here with a speech then tirs232 sidecar, 32k then tipi all works fine

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On the original sidecars, the final spec actually allowed up to six devices. TI manufactured five different sidecars, and when you put the Thermal Printer onto the train, that made six. . .

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Probably bus buffers.

 

I haven't seen a TI 32K sidecar, but I bet it has some 74'244 and 74'245 chips before the right hand port.

 

Anyway, that's just a guess.

 

[email protected]

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Posted (edited)

Hey guys,

 

Sorry to bump an old thread, I just wanted to record for posterity that the modern 32k sidecar DOES work as the third car in the chain (after a Disk Controller) with an external power supply. Thanks for the help, everyone! :)

 

 

post-63949-0-69635500-1555972339_thumb.jpg

Edited by Chefgon
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Posted (edited)
On 4/10/2019 at 1:51 PM, Chefgon said:

I've heard that the Disk Controller has to be last in the chain, but I find it odd that it has a pass-through port on the side if nothing will work in it.

That pass-through port on the side of the Disk Controller is for the Thermal Printer, IIRC.

Edited by iliketurtles

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