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Sidecar signals - bringing them to a cart board


acadiel

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This is a project I have been noodling for a while, mostly for the idea of prototyping using a cartridge type board instead of the side car. Just wondering if anyone would actually use it or not.

 

Premise: bring the 13 missing pins on the side port to a cartridge port device with a small ribbon cable. The side port would be a simple male to female connector, probably 4" or so long, with a 14 pin header on it. A small female to female header (only long enough to reach the modified cart board) would be installed on it. The modified cart board could likely latch onto these 13 extra signals (plus a ground) as well as all the extra signals that are cart port only (think the GROM and ROMG* signals) Likely use of this could be prototype of new sidecar equipment, DSR devices, or anything that needs the there address lines which will now be there. Jumpers would be available on the board, and I have thoughts for a ROM only version right now. I could make jumpers to where a certain part of the EEPROM could take over the DSR >4000 space, for example.

 

So, here's what would be brought over:

 

SBE

AudioIn

Reset*

Extint*

Ready

Load*

Phi3*

Mbe*

Memen^

IAQ

A0

A1

A2

GND

 

Anyone interested in me even spending the time on it, can think of any use cases for it, etc? Just think how much more control and fun we could have with those extra signals :-)

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Looking at it from the other direction, are there pins exclusive to the cartridge port not present at the sidecar? If the sidecar port alone had all the pins you needed. design something to fit in a speech synth box and you'd still have the stock cart port for something else, no linking cable would be needed.

 

I don't know the hardware end of it, so this may be a dumb question, but I had to ask it anyway! :P

-Ed

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Or build a short bridge board like the GROM Busters that has a 44-pin socket that you can connect a side-port cartridge to. You could do neat/crazy stuff like make an AMS sidecar or cartridges that used up to 40K of non-banked space, or lots of other possibilities. . .and it also works as a pass-through, so it could still work with a PEB, although you'd have to make a 32K plug-in for it to avoid putting a memory card in the PEB when you're not using one of the side-port cartridges.

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Even with modern components and component density, would it be possible to cram an entire AMS into the remaining space of a speech synthesizer? That concept blows my mind. That would be totally awesome, barring any issues unforeseen compatibility issues, because not only the P-Box users could use it, the Nano-PEB guys and the CorComp expansion guys could use it too.

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You can get a single chip ram organised as 1M x 16 bits (2 megabytes), add a paging circuit and put it under the 9900 in the console, it could then "page out" all the 8 bit nonsense, only paging it back in when absolutely necessary, add a new operating system and then you will see what the 9900 is really capable of.

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The AMS is only a half-size card now--and that has a lot of open real estate. I wouldn't quite put it in the Synth case in any event. I'd modify a synth case to put a Tiger Vision/Exceltek cartridge sized slot in the top and build the rest as a pass-through box with the receiving socket in the middle of the board. You'd just have a double speech synthesizer attached to the side of the machine--and you could make the cartridges with boards in them relatively tall in a custom case, with cartridges in a shorter one.

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Looking at it from the other direction, are there pins exclusive to the cartridge port not present at the sidecar? If the sidecar port alone had all the pins you needed. design something to fit in a speech synth box and you'd still have the stock cart port for something else, no linking cable would be needed.

 

I don't know the hardware end of it, so this may be a dumb question, but I had to ask it anyway! :P

-Ed

Yes, there are five that come to mind:

 

RESET (note the side port has RESET*)

GROM select*

GROM clock

GROM ready

ROMG* (active low if cart rom is used)

 

These are not present on the side port.

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Or build a short bridge board like the GROM Busters that has a 44-pin socket that you can connect a side-port cartridge to. You could do neat/crazy stuff like make an AMS sidecar or cartridges that used up to 40K of non-banked space, or lots of other possibilities. . .and it also works as a pass-through, so it could still work with a PEB, although you'd have to make a 32K plug-in for it to avoid putting a memory card in the PEB when you're not using one of the side-port cartridges.

We'd have to figure out how to obtain the missing ROMG* signal (and the GROM ones) on the side though. I don't know how easy those are to generate? (Obviously, you can get around it like with the PGRAM and HSGPL).

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Note that the five existing side-port cartridges don't use these signals, Acadiel (the fifth one is the Hamsoft module). Another good idea is to look at how the p-Code card powers up, as it has 8 GROMs on it. That may give you a good set of external GROM-control circuitry. . .although I think a lot of it is in the PAL on the p-Code card, IIRC.

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Yep, and the ones on the side are typically ROM carts that are not banked, or also live in the DSR or memory expansion space. I believe ROMG* (pin 34) was used in the 74LS378 somehow for our bank switching scheme, but can't verify unless I pull up ExpressPCB. About the GROM decoding circuity, yeah, that's why I wanted to just bring the seven signals to the cart port so we can just pull from them all there. :-)

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