A1200 extension cable for the expansion port?

[guybrush]

Is there anyone selling extension cables for the expansion port of a 1200?


I saw online extensions for things like PCI-E (very useful for motherboards that have the PCIe x16 slot too close to the CPU area or to other slots), so I thought that maybe someone made a similar cable for the Amiga too; but so far no luck in finding it.


The idea is that I found a nice case for my 1200 but the expansion board goes right where the hard drive/cd cage is located; so either I butcher the case and the drive cage, or I find a cable to move the expansion port out of the way, so I can have the expansion board moved out of the way.


Not being a standard connection it is even hard to find suitable connectors; I wish there was a ribbon cable connector option on the board, something like the IDE connector which is awesome in terms of space management

[Jpor]

Originally Posted by guybrush

Is there anyone selling extension cables for the expansion port of a 1200?


I saw online extensions for things like PCI-E (very useful for motherboards that have the PCIe x16 slot too close to the CPU area or to other slots), so I thought that maybe someone made a similar cable for the Amiga too; but so far no luck in finding it.


The idea is that I found a nice case for my 1200 but the expansion board goes right where the hard drive/cd cage is located; so either I butcher the case and the drive cage, or I find a cable to move the expansion port out of the way, so I can have the expansion board moved out of the way.


Not being a standard connection it is even hard to find suitable connectors; I wish there was a ribbon cable connector option on the board, something like the IDE connector which is awesome in terms of space management

You can get the Expansion connectors which are used to replace faulty ones on Amiga expansion/accelerators. I think the challenge is the further away you make a connection the more the voltage drop to the accelerator. Especially if you plan on using a Blizzard PPC card.

[Krashan]

Originally Posted by Jpor

I think the challenge is the further away you make a connection the more the voltage drop to the accelerator. Especially if you plan on using a Blizzard PPC card.

It is more about high speed signal integrity and crosstalks. Extender introduces additional inductance and capacitance to the circuit, and bandwidth of signals going trhough the port is in range of tens of megahertz. Signal edges will degrade.

[Jpor]

Connectors for the A1200 can be found here;

https://www.ebay.co.uk/itm/New-Black...-175127-2357-0

[guybrush]

Thanks; so unless they are active extenders with a signal amplifier, there is a risk to degrade the signal, even for short distances (5-10 cm)?
I guess PCI-E signal is much stronger, since you can use those flexible PCI-E extender to relocate your video card.

Thanks for thie hints! I will get a couple of connectors and try different cable length to experiment with signal strength. I should be able to use an oscilloscope to get the signals from the pins and see how far I can go with the connector, If I could just flip it 180 degree that would be already enough

[Daedalus]

It's not that PCIe is a stronger signal as such, but it's a serial signal (or several serial signals) that are intended for transmission over longer lines. It's therefore more robust and reliable when it comes to extenders.

Yes, noise and signal degradation are significant concerns, but I've personally managed to extend the bus by about 8cm using a ribbon cable, and it performs solidly with a Blizzard 1230 on the end, flipped over so it can fit in the case I used. Your mileage may vary, of course...

[guybrush]

Originally Posted by Daedalus

It's not that PCIe is a stronger signal as such, but it's a serial signal (or several serial signals) that are intended for transmission over longer lines. It's therefore more robust and reliable when it comes to extenders.

Yes, noise and signal degradation are significant concerns, but I've personally managed to extend the bus by about 8cm using a ribbon cable, and it performs solidly with a Blizzard 1230 on the end, flipped over so it can fit in the case I used. Your mileage may vary, of course...

I see; I thought that PCI-E was not meant to be transported over long distances; hence the fact that external GPU enclosure use thunderbolt to communicate.


So you made one and it works? 8 cm is more than enough for me; I just need the accelerator card relocated to leave the bottom corner free

I was thinking to make a breakout board for the edge connector; with pcbway you get the PCB done for quite cheap, although you need to order at least 10 of them I believe; so that is 10 connectors to buy ahead of time, and it seems nobody really care about extensions for the edge connector

[Daedalus]

Long is relative Some people report issues with Clockport cables longer than 10cm (which is essentially the 68020 bus), whereas PCIe often travels longer distances than that in a PC. Besides, Thunderbolt is essentially a brand name for PCIe in a cable along with a couple of extras, which is how external GPUs work in the first place.

For my extension I used one of the Elbox Mediator trapdoor passthrough adaptor boards, desoldered the edge connector and put it on a ribbon cable. That gave me the PCB edge I needed without having anything made. I have a couple of photos of the end result here. That was a long time ago now though, and those adaptors were cheap at the time. For €60 nowadays, having a few PCBs made up might be far cheaper. You never know, a couple of people might buy the blank PCBs and offset the cost.