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3rd party extender/receiver cards

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bettablue

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I have been in the middle of some pretty intersting private conversations with several people who either have, or want an IBM 5161/2 expansion unit for their PC. Most of them are all asking the same question. Even Marcoguy is involved with this right now too because he intends to do what I was going to do before I got my expansion unit... That is, he wants to try to build his own from parts he can get from the web. We can get IBM XT cases, and power supplies. We can even get 8 slot, 8 bit passive back planes or planars. The only thing we can't get are the extender and receiver cards.

I ran into a company a while back (but I can't seem to find them any longer) who had 8 bit extender and receiver cards. They werent all that expensive either. I believe they were in the $69.95 area plus shipping and handling for each card. The main issue there is that they didn't have any more in stock. Since they were the manufacturer, they could make more, but they would only make them in batches of 100 or more. That meant that to me at least, they were completely out of the equation as the price was just too high.

So, on behalf of myself and the other 4 or 5 of us looking for replacement excender and receiver cards; does anyone know of a 3rd party vendor I might be able to contact for small orders?

PS. I'm still looking for someone who can make the drive bay covers for less than $30.00 apiece.

Thanks much.
 
What do you mean by an "extender" card? In my little half-acre of jargon, that means a card that plugged into a slot and had an edge connector on top. The idea was to raise a card being worked on above the case so one could see what one was doing.

They were offered by a lot of outfits, including generic Taiwanese. My own happens to have been sold by JDR.
 
The extender card is the one that plugs into the 5161 and connects to the receiver card (the one that plugs into the system unit).
 
Are we now talking about the two cards needed to get a 5150/51560 to talk to a 5161 style second case with a bunch more expansion slots?

I thought all the cards really did were buffer and add a wait-state - if that (probably way too simplistic) view is correct, it should be pretty easy to design our own?
 
Yep. We are talking abut the two cards that connect a 5150/60 to a 5161. I have no idea exactly what it does other than connect the two.
 
pearce_jj said:
Are we now talking about the two cards needed to get a 5150/51560 to talk to a 5161 style second case with a bunch more expansion slots?

I thought all the cards really did were buffer and add a wait-state - if that (probably way too simplistic) view is correct, it should be pretty easy to design our own?
Click to expand...

That's exactly what we're looking for pearce.

I know Marcoguy, and I would both like to buy a complete set, as well as others who have posted here looking for replacements for the one or the other. Usually the extender card is the one that goes missing. Marco and I are both going to be building our own expansion units for different yet similar reasons. Marco wants to be ready in case the 5161 he's after falls through, and I want to be able to build one from parts I have located on the Web, for my best friend who has been helping me with my system.

The thing is, I'll never be able to make something like that. My electronics knowlege is seriously lacking. Hell, I wouldn't even get to the first step. I don't know about marcoguy.

There are at least 6 or 7 people that I know of from looking at posts in different sites who are looking for replacement extender cards for various reasons. If someone were to make a batch of matched sets, and sell them for $129.00 or so. (Just guessing) They would probably sell pretty quickly on E-Bay, or the VCF Marketplace.
 
I couldn't even begin to make my own set. pearce_jj, I am aware that you have done some work making ISA cards. If you could get some information on the blueprints or even a working model of the cards, maybe you could make a batch.
 
There were other companies that made expansion chassis so there are other cards as long as you are not interested in an original IBM. I think Magma used to have an ISA box although now it is all PCI/PCIe. Tecmar also used to make them. There is one on sale on eBay right now. So making other cards should be possible. Hell, you may be even able to copy the IBM design directly. I don't think there is a BIOS or any sort of programming on the cards. So as long as you put the same component on a board w/ the same tracings it SHOULD work. But hey, I am not an engineer so I am just talking straight out of my back side on this one! Of course there is also always the copy right issue.

Some more options here.
A card and cable set here. These guys still sell the set and with their set you can expand up to 20 slots instead of the 8 on the 5161.
 
Last edited:
hello
besides agreeing with ShadowLord, I can tell the Tecmar version also seems quite simpel.
But it works ! I did a scsi HD boot and a floppy boot from the expansion unit.
(my unit is due to get some service - when I changed the transformer from 110 volt to 220 volt , I did forget the fan. 1/2 hour later there were a distinct smell of .. burned fan-motor :(
.. just acquired another Papst 220v fan , and looking forward to installing it !)
/cimonvgUnavngiven.jpg
 
Yup, the Tecmar unit definitely had the best bang for the buck--and was probably the easiest way to add a hard disk to a 5150.

I scrapped a transmitter card a few years ago that was essentially a clone of the 5161 type. The PCB was blue, so I suspect it might have been Quadram or STB--I don't recall.

If you were to roll your own today, It's probably make some sense to combine the receiver card and the backplane on a single PCB, rather than use a slot for it.
 
The only thing is that bigger boards cost (considerably) more.

But, I'm wondering how the card add the wait-state - it implies some method to sense that the particular operation is being handled by a card at the other end of the extender. Surely the reply would have to have been received, for it to know, in which case it's too late?
 
pearce_jj said:
The only thing is that bigger boards cost (considerably) more.

But, I'm wondering how the card add the wait-state - it implies some method to sense that the particular operation is being handled by a card at the other end of the extender. Surely the reply would have to have been received, for it to know, in which case it's too late?
Click to expand...

The actual wait-states are generated by a pair of flip-flops and a comparator. It first compares the upper 4 memory lines to see if the addressed memory is between (but not including) segment [Sw1]* and segment F. If so, then it checks if there is a memory access at all by using the /MEMR and /MEMW lines, and then finally the I/O CH RDY line may be pulled low unless /DACK0 is active. See the diagrams in the options and adapters manual for more info.

(* [Sw1] values are 0=on, 1=off)

The cards does quite a bit more, like latching the data and address busses on both cards so you can read back if all signals has successfully passed through the cable (in other words, to check if the cable is broken or not). There is also cirquits to disable the extender card, and of course cirquits to controll the direction of the transceivers and such.
 
Thanks, will check out the detail. But it sounds simple enough. I'm thinking a board with pretty much just a VRM and an XL95144XL in TQFP144 format, plus a connector to utilise some pre-existing and available 52-pin+ cable. Both boards would be identical, but loaded with different CPLD code or maybe a switch/jumper to configure which end.

Cable wise initially SCSI 3 jumped out (68-pin) but being LVD presumably the pairs are twisted, which I guess might be a problem.

How would ground be handled between the two ends?
 
pearce_jj said:
How would ground be handled between the two ends?
Click to expand...

Ground is routed through the cable on six wires and connected on both sides. Chassis is also routed together through the cable-shield. The original IBM cable uses 22 AWG wires, so it should be plenty.
 
I just found this on minuszerodegrees.net:


Extender Card

The extender card is a four-plane card. It re-drives the I/O
channel to provide sufficient power to avoid capacitive effects of
the cable. The extender card presents only one load per line of
the I/O channel.
The extender card has a wait-state generator that inserts a wait
state on memory-read and memory-write operations (except
refreshing) for all memory contained in the expansion unit. The
address range for wait-state generation is controlled by switch
settings on the extender card.
The dual-in-line package (DIP) switch on the extender card
should be set to indicate the maximum contiguous read/write
memory in the system unit. The extender card switch settings are
described under "Switch Settings" in the Guide to Operations
manual. Switch positions 1 through 4 correspond to address bits
hex A19 to hex A16.
The DIP-switch settings determine which address segments have a
wait state inserted during memory-read and memory-write
operations. Wait states are required for any memory, including
ROM on option adapters, in the expansion unit. Wait states are
not inserted in the highest segment, hex addresses FOOOO to
FFFFF (segment F).


Receiver Card

The receiver card is a four-plane card that fits in expansion slot 8
of the expansion unit. It re-drives the II0 channel to provide
sufficient power for additional options and to avoid capacitive
effects. Directional control logic is contained on the receiver card
to resolve contention and direct data flow on the II0 channel.
Steering signals are transmitted back through the expansion unit
cable for use on the extender card.
The following is a block diagram of the receiver card.
 
You'll find the schematics in the 5160 Techref (should be on minuszero).

Is there any particular overwhelming reason why a ribbon cable couldn't be used? Assembling a 62-conductor round cable in small quantities is going to be expensive otherwise.
 
I've entertained this idea before as well, but the demand is really really low. From a purely functional objective, existing or newly designed multi-function cards ease the need for more slots. And those wanting to keep the system stock IBM won't be interested in a after market extenders anyway. From a technical perspective using SMT, an alternate way to tackle this might be to convert ISA signaling to LPC then use a single differential pair for each uni-directional LPC net and a dual pairs for each bi-directional net. Should be possible to use a telco 25 conductor cable assuming the drive strengh, switching speeds, and cable impedance is all where it needs to be.
 
eeguru said:
I've entertained this idea before as well, but the demand is really really low. From a purely functional objective, existing or newly designed multi-function cards ease the need for more slots.
Click to expand...

The 5161 and its clones were never popular--they were expensive, and, as both you and I have observed unnecessary once multi-function cards made their appearance. At some point, one runs out of interrupts or I/O space (why the 5150 specified that only 10 bits of I/O address space needed to be decoded, I'll never understand), so all those expansion slots aren't terribly useful.
 
Chuck(G) said:
The 5161 and its clones were never popular--they were expensive, and, as both you and I have observed unnecessary once multi-function cards made their appearance. At some point, one runs out of interrupts or I/O space (why the 5150 specified that only 10 bits of I/O address space needed to be decoded, I'll never understand), so all those expansion slots aren't terribly useful.
Click to expand...

I'm having a hard time understanding a historical use for these as well. If I had one I wouldn't know what I'd use it for. Does anybody know what these expansion units were sold for?
 
Ole Juul said:
I'm having a hard time understanding a historical use for these as well. If I had one I wouldn't know what I'd use it for. Does anybody know what these expansion units were sold for?
Click to expand...

Well originally they allowed you to add a HDD to the 5150 and have more cards in each unit (e.g. multiple serial ports). But I believe mainly the focus was on HDD as the PSU on the 5150 was quite anemic. Now a days they serve a function equivalent to having a fully functional XT for most people: it is a reminder of a much more civilized time. ;)
 
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