Amstrad CPC Expansion Port Raiser with multiple edge connectors, any interest?

[ikonsgr]

Hi Everyone,

  With more and more expansion boards coming out for amstrad cpc in recent years,  (M4, RAM/ROM boards etc), the one and only epxansion port might be a problem, if you want to connect more than one of these boards to your amstrad. So, i was thinking of making a cheap "raiser" for the expansion board, which will give you 2 or 3 expansion ports.In order to do that,i designed a special double side 50pin edge2edge adapter that will go into a typical female edge connector and convert it to "male" edge connector! 
I believe i could make a raiser with 2 expansion ports for less than 10euros, but as i dont know if there is any interest in this, i don't know how many special boards to order to the pcb manufacturer. So, anyone intersest, let let me know by posting here.

[Bryce]

There are already several different versions of this being made by other members such as the MX4 and other variants (from Duke if I remember correctly). What would this new board offer that they don't?

Bryce.

[ikonsgr]

To tell you the truth, i didn't know that (although i couldn't find anything on ebay) ...  
Anyway, are any of these versions you say are still available? And at what price?

[Bryce]

It was actually @LambdaMikel , not Duke that made an alternative: http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/motherx4-alternative-for-cpc-464-users/msg161349/#msg161349

You'd have to ask him or @TotO whether they have any for sale.

Bryce.

[Skunkfish]

It sounds like the difference here is that multiple edge connectors rather than IDC type connectors are provided? Although @LambdaMikel 's version does have an edge connector as well..

[Bryce]

Edge connectors are a dodgy connection at the best of times. They should be avoided where possible, which is why I (firstly on the MegaROM) and later others used 2.54mm header connectors instead.

Bryce.

[LambdaMikel]

Right, and I am crazy enough to sell some of them assembled as "CPC community service" (no, can't retire early from this  )
https://www.sellmyretro.com/user/profile/cpcmichi/

[LambdaMikel]

Edge connectors are a dodgy connection at the best of times. They should be avoided where possible, which is why I (firstly on the MegaROM) and later others used 2.54mm header connectors instead.

Bryce.

Yes, but some new and old hardware (DDI3, DKtronics speech synthesizer, SSA1, ...) require it.
It is not that bad if you only have one device like the DDI3. Reliability also increases *a lot* if
you use it one the LambdaBoard edge connector sitting on the stable table rather than hanging
from the CPC edge.

[ikonsgr]

Wow, LambdaMikel this is a really BIG contraption!   
But as already said, amstrad cpc has edge connector for expansion port (most of them anyway, cpc with centronics are much fewer then with edge connectors)and not idc, so using 50pin female edge connectors is mandatory (all of old addon baoards and most of the newer ones use edge connector, obviously because amstrad cpc is equipped with edge connectros... ).
  The idc approach is nice and reliable, but apart from needing the MX4 board, it should require  the expansion board to have custom  idc connectros to use it.

What i was thinking, is something much more "universal" (e.g. use ANY epxansion board) and simpler (and most probable easier and cheaper to make) , just a 50pin ribbon cable, with a bunch of 50pin female edge connectros on it. The fisrt should be plugged into amstrad cpc expansion port, and all the others will be fitted with the custom  edge2edge adapter i designed, in order to "convert" the female connectors to "male" edge connectors! I desgined the board to have ~2.2cm height, so since each edge connector goes up to ~1cm into the female connector, this leaves a "gap" of only ~2-3mm, which i suppose will be rather reliable and robust without any danger of breaking anything.

[ikonsgr]

It sounds like the difference here is that multiple edge connectors rather than IDC type connectors are provided? Although @LambdaMikel 's version does have an edge connector as well..

Exactly! It would be as if amstrad cpc has 2 or 3 edge connector expansion ports instead of one! 

[LambdaMikel]

What i was thinking, is something much more "universal" (e.g. use ANY epxansion board) and simpler (and most probable easier and cheaper to make) , just a 50pin ribbon cable, with a bunch of 50pin female edge connectros on it. The fisrt should be plugged into amstrad cpc expansion port, and all the others will be fitted with the custom  edge2edge adapter i designed, in order to "convert" the female connectors to "male" edge connectors! I desgined the board to have ~2.2cm height, so since each edge connector goes up to ~1cm into the female connector, this leaves a "gap" of only ~2-3mm, which i suppose will be rather reliable and robust without any danger of breaking anything.

Interesting idea. I guess I would need to see a use case to fully understand.
So, let's say first we have a female female cable from CPC 464 edge, and plug your edge in there. That gives us the male edge. Then I can connect, for example, my DDI3 or DKtronics at the end, as if it was plugged directly into the CPC. However, how do I connect the next device now. The DDI3 does not have an output connector, and the DKtronics or SSA1 have a male edge connector already.


So, how do I do some port splitting "or daisy chaining" with your adapter?

[LambdaMikel]

just a 50pin ribbon cable, with a bunch of 50pin female edge connectros on it.

So, there will be multiple ribbon cables coming out of one female edge connector (to be plugged into the CPC's edge)? How do we make such as thing?


Ahh... I see... you mean you will crimp a couple of these female edge connectors onto the cable. Yes, that could work!
So basically, the ribbon cable will be your "motherboard" then... the only drawback maybe being that the devices will be "lying" then instead of standing upright. That might be a good thing for DDI3 or so, but maybe not so great for a SSA-1 or DKtronics speech synthesizer. Curious to see if this will work from a signal / electrical point of view, too. I.e., try this with 4 MB RAM expansion (XMem or Piotr's). It's actually quite hard to get this to work reliably, cable length etc. THese devices are extremely picky regarding signal runtimes.

[LambdaMikel]

So, there will be multiple ribbon cables coming out of one female edge connector (to be plugged into the CPC's edge)? How do we make such as thing?


Ahh... I see... you mean you will crimp a couple of these female edge connectors onto the cable. Yes, that could work!

Having said this - you could even have a mixture of female edge connectors and IDC box headers crimped onto the same cable. That way, you could also support M4X devices 
Somebody has tried that before?

[IanS]

Reversiboards are more useful. Crimp on a new IDC connector to the ribbon cable, insert reversiboard, instant new edge connector for any expansion device.http://www.cpcwiki.eu/forum/news-events/x-mem-a-new-memory-expansion-for-all-cpc/msg79798/#msg79798

[LambdaMikel]

Cool, didn't know about ReversiBoard!
Seems the CPC community has explored all permutations / combinations of connectors by now -- not so easy to invent a better mouse trap these days   

[ikonsgr]

Well,it seems that  i redesign the "Reversi-board" then... 
LambdaMIkel, it's exactly like you described. The multiple 50pin connectors on the ribbon cable will be..."bisexual"  , you can use them as they are for connecting any device with edge connector, or plug the "edge2edge" adapter (or "reversi board" as other called it) ,convert them to "male" edges,and  plug any device equipped with female edge connector (these are intend to be used directly with original cpc expansion port anyway).
And ofcourse you could even plug extra 50pin idc female connectors too, to give even more "universal" flexibility! 

As for your concerns about the ribbon cable length and reliability, let me remind you that old IDE devices used for decades on PC computers, used exactly this type of ribbon cable with multiple connectors on it, and in up to 50cm-60cm in length. These ribbon cables worked perfect with HDD and CD/DVD drives, transferring signals between motherboards and devices up to 33Mhz!
So, no matter how "extremely picky" a 4 MB RAM expansion (XMem or Piotr's) might be, communications through cable will be always at 1Mhz (amstrad's motherborad speed), can this ever be "pickier" than an IDE device working on 33Mhz?

[ikonsgr]

Btw,so far, i didn't see anyone interested in this kind of device (or for the edge2edge boards). I guess only the few "hard core" amstrad users might needing this( and most probable have already solve the problem of multiple connectors, using other solutions), so i will order 4-5 boards  for myself then, just to see if it really works... 

[Bryce]

As the only hardware that needs a real edge connector are older devices (almost all new devices are in "MX4" format), how about designing a riser the would convert an MX4 header port back into an edge for connecting those few existing older devices?

Bryce.

[ikonsgr]

As the only hardware that needs a real edge connector are older devices (almost all new devices are in "MX4" format), how about designing a riser the would convert an MX4 header port back into an edge for connecting those few existing older devices?

Bryce.

You mean that all newer boards designed for amstrad cpc, use idc connector instead of edge connector? I really didn't know that....
But then, you will always need an extra adapter board like MX4, to plug it to your amtrad. Which is not a problem if you want to plug more than one boards, but surely is a waste if you just want to connect one board to your amstrad.... 
Unless if.... practically, the vast majority of users interested in these expansion boards are only "Hard core" ones, that have hole collections of expansion boards to their possession,so needing an extra multi slot adapter board would be no problem! 


P.s. Interesting idea about the adapter you say. But instead of redesigning the board, you think that if i put the one end of the edge2edge adapter between a dual row 25pin idc header and solder the pins, should work ok?

[ikonsgr]

Btw, soon i will be presented an "open project" of a cheap and easy to use Serial port interface for amstrad cpc, the board i designed is using a dual row idc header where i plug a ribbon cable with a female idc conector in one end, and a 50pin edge connector on the other in order to connect it directly to an amstrad cpc expansion port. So, i suppose this should be able to plug into mx4 board directly, right?

[Bryce]

No, most new boards use a 2.54mm header (straight or 90°), ie: these:
https://www.audiophonics.fr/9333-large_default/2x25-angled-pin-header-connector-pitch-254mm.jpg

You can use these then with an MX4 type board or if you don't want an MX4 or only want to connect one expansion, then you simply make or buy the correct connection cable like these: http://www.cpcwiki.eu/imgs/8/8a/MegaROM_Cables.png


The advantage being that the device designer only needs to design one layout and it will work with any type of CPC with the appropriate cable. No need to design an edge and a centronics version of the device.

Bryce.

Edit: I think you are possibly mis-using the abreviation IDC. IDC stands for Insulation Displacement Connector and refers to connectors (such as flat cable connectors) that self connect to the cable just by pushing the cover down on the cable. A PCB header connector cannot be IDC.

[LambdaMikel]

As the only hardware that needs a real edge connector are older devices (almost all new devices are in "MX4" format), how about designing a riser the would convert an MX4 header port back into an edge for connecting those few existing older devices?

Yes, but old devices are important, ie., the DD1 disk controller, the DKtronics line of hardware, ... so they need to be supported 
I find it unfortunate that people are mostly 6128 users here and tend to forget how important the edge connector-based hardware is for 464 users.

[LambdaMikel]

Btw, soon i will be presented an "open project" of a cheap and easy to use Serial port interface for amstrad cpc, the board i designed is using a dual row idc header where i plug a ribbon cable with a female idc conector in one end, and a 50pin edge connector on the other in order to connect it directly to an amstrad cpc expansion port. So, i suppose this should be able to plug into mx4 board directly, right?

Is it going to be compatible with
http://www.cpcwiki.eu/index.php/Amstrad_Serial_Interface ?
I would definetly be interested in such a device; one of the missing pieces in my collection.

[ikonsgr]

Thanks for the info Bryce!
Well practically i did the same thing with my serial port board,use pin headers on the board (btw, yes you were right that i "missuse" the term idc for both connector and pin headers   ), and a small ribbon with idc +edge connector to plug it directly to expansion port. And changing the edge to centronics, will do for amstrad/schneider cpc too, so this desing is really a "universal" one!
Still, these connection cables (from idc to edge/centronics), are they always available and easy to find? 50pin edge connectors nowadays, are rather difficult to find and they are rather expensive if you want to buy just 1-2 pieces, (centronics can be found more easily but they are expensive too ~4-6euros/piece),and also not anyone can make a ribbon cable with connectors by himself, right? 
I really don't know how many of amstrad users have or want any expansion board and thus, need(or can make by themselfs) such connection cables, from my experience of selling items for amstrad cpc over the last 5-6 years on ebay, i could say that most people  just want an easy and cheap way to "revive" the old memories, usually a ribbon cable + Y power cable for external drive connection, and maybe a gotek/Hxc/3.5" drive too.
But maybe you can give us a more accurate view on the subject, as you are admin at cpcwiki and you constanlty dealing with all these "curious" expansion boards for amstrad cpc!

[ikonsgr]

Is it going to be compatible with
http://www.cpcwiki.eu/index.php/Amstrad_Serial_Interface ?
I would definetly be interested in such a device; one of the missing pieces in my collection.

Well,i don't think so (and reading the article about it, it was rather complicate design with rather low speeds and limited usage) . 
The serial interface i design is a "from the scratch" project, based on a PIC microcontroller, and it would be a "universal" serial interface, where you can connect a direct serial cable(or usb to serial adapter,you know these cheap ones with the 4 pin headers, 5v, gnd, Tx,Rx), an HC-05 wireless bluetooth module, or even an ESP8266 wifi module!
For the moment, i've tested it sucessfully with speeds up to ~0.5mbit (these speeds were "science fiction" back at the days of serial interface... ). I have also developed utilities for chat and file transfer  between amstrad and a PC. My intention is to make this a rather easy and cheap 'open source" project, where i will give everything for free (from board schematics and hex file for the PIC MCU, up to the utilities for pc and cpc), and, who knows, maybe in the future could establish a new "standard" for amstrad serial interface! Just imagine developing multiplayer LAN or even WAN games using it... 
I'm also thinking of giving a few "Early boards" to anyone interested in testing and using this, but enough said already, soon i'll make a full presentation here at cpcwiki, and we could talk about it there.


P.S. To catch Bryce , i know that there is at least another serial interface project using the good old 16550 chip, but my design based on a modern PIC mcu, would be  much easier and cheaper to make, and most important, VERY easy to use, just one out() for send, and a couple of inp(), for checking if there is a byte available and receive it, no need to setup anything else, except from the serial port speed, which can be altered "on the fly" too!