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Multi-Cards (8Bit/16Bit)

D

dr.zeissler

Experienced Member
Joined
Jan 4, 2014
Messages
417
Location
Germany
Hi,

due to the lack of enough ISA-Slots I always wondered, why nobody offers new Multi-Cards.
There are project for XT-IDE, VGA, Network-Cards etc. but nobody has build a plattform-system
that is really flexible. Is it a hardware-problem that such things are not possible, or to expensive?

e.g.:

I own a T1000 RL/HD. It has a XT-IDE in the only 8Bit-ISA Slot.
Therefore a combination of an XT-IDE with a VGA or a SB or a MPU401 or a real in/out LPT-Port would be very nice.

dOC
 
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It's more of a supply/demand problem.

Sure it can be done (I have an EGA / parallel port / serial port combo card) but there just isn't enough interest to justify the production time/costs. IDE & serial / parallel ports are easy enough to implement, making a good VGA adaptor is harder but still possible. What eventually happens though is space runs out at the rear of the card to fit all of the connectors (i.e. DB15 for VGA, DB9 for serial, DB25 for parallel etc) and you need to branch them off with headers. The headers then usually connect to a ribbon cable which connects to a couple of connectors on a rear plate (taking up another 'slot space' on the computer).

Also you have the problem of person X wants CGA,Serial and XT-IDE, person B wants VGA, parallel and XT-IDE and person C wants EGA, no serial or parallel and XT-IDE. You could easily disable the serial / parallel ports but having multiple video adaptors on one card would be tricky at best. Also your effectively paying for functionality you probably dont want or need.

Personally I think it would be cool to see a new combo card produced; but given that vintage computing is primarily just a hobby I think it wont happen.
 
Also we quickly run out of board space whilst keeping through-hole components, meaning it would likely end up being a full length card. And those are VERY expensive to produce in small numbers (not to mention the software licensing).
 
pearce_jj said:
Also we quickly run out of board space whilst keeping through-hole components
Click to expand...

Any qualms about using SMD components? I know it won't keep that vintage feel, but I think it'd be way more practical, and opens us up to way more types of available chips that'll really shrink down the board footprint. As an exercise, one of the first things I'd like to do with the old wire-wrap ISA proto board I just found in an old warehouse is use some of the old SIMM memory lying around in my house as expansion for my 5150 to bring it up to 640K from 256K. One tiny lil' SIMM oughtta leave plenty of space for a whole lot else... :D
 
I've found that squirting a line of solder paste + chisel tip soldering iron + slide down the pins= can do chips in seconds! It can be fun in it's own right once you've done a few projects. But I do hate fiddling with tiny fiddly little resistors etc.

For me, through hole components for 2-3 pin stuff, and SMD for IC's is actually the preference.
 
SpidersWeb said:
I've found that squirting a line of solder paste + chisel tip soldering iron + slide down the pins= can do chips in seconds! It can be fun in it's own right once you've done a few projects. But I do hate fiddling with tiny fiddly little resistors etc..
Click to expand...

That's fine when working with SMD that has a reasonable pin width/pitch. For example I have soldered a lo-tech EMS card using the method you mentioned above. That being said I also solder SMD at work using paste and a rework station which is 1000x easier and leaves a much neater finish.

When you get to SMD with a high pin count in a small package the soldering iron doesn't work. The mask is too thin and the pins just bridge out instantly. You can clean it up using some solder wick but it's very easy to end up with dry joints.
 
Both solid approaches for soldering SMD. Usually I use a blob of solder on the iron's tip rather than solder paste. The rework/reflow setup becomes necessary for QFN parts, which are real "fun" to get lined up by hand, especially if anything goes wrong after the first attempt. :sarcasm: I've had bad luck with reworking stuff though, since usually something ends up burnt or cracked. With practice comes refinement & elegance...

Anyway, it might help to figure out footprints for the various types of adapter circuitry (e.g. chips required & physical space) and then find some way to jam them all together onto a PCB on-demand to the user's request, or at least pre-define several key combinations. Probably even better is to simply make the PCB support as much stuff as possible but only populate components for that which the user desires. PCB cost is usually not high compared to your components, especially when you minimize variations on the PCB. Otherwise you're looking at a lot of art fees, setup fees, minimum order sizes per design, etc; just for a few dozen 5"x7" panels of one design, I've had it close to $1K to get PCBs made (not including parts or assembly) from a local manufacturer with decent turn time (which you'll want for at least the first few go-rounds given the superior quality & customer service). The Voltera could inspire a lot of folks to do small runs of this (plus all sorts of other) hardware, but it could still be a lot of money just to buy all the one-off parts you'd need to make it work... and then, does it ever work right on the first revision? ;) With all that, you still have make sure you aren't violating anyone's IP, and obtaining (let alone reverse engineering) any necessary firmware to run the adapter could be challenging, as pearce_jj suggested.

Hopefully, if a lot of people are averse to SMD, they can at least tolerate DIP-socket ATmega's or PIC chips handling most of the task. Looks like my HxC2001 SD/floppy emulator runs with a PIC chip, and it works great!
 
Chuck(G) said:
Yes--I've had a couple of VCF projects shot down because it involved SMT components.
Click to expand...

I think if you used GALs or a CPLD for things like address decode instead of 7400 logic, a lot of space could be saved and it might be possible to create a useable full-length ISA multicard with quite a few features packed in.

Ports are a harder problem. Maybe do something like a higher-density connector and an external breakout box to the actual connectors?
 
Sure--and I do that on occasion. But folks need to program the GALs or CPLDs--and 5V parts are getting scarce. I recently did a project using an XC95108 (84 pin PLCC). I'd never dream of making that a project for the masses--just too hard to find parts, much less programming for them.

Face it--we live in a 3.3V (or less) SMT world. Remember when digital ICs were in TO-100 and flatpack?
 
I don't think I was born in the TO-100 and flatpack days ;)

Atmel still has 5V SPLDs and CPLDs that are in production, and there are still Altera 5V FPGAs floating around... But I agree the 5V programmable logic seems to be going away.

I don't think I'd completely rule out a project with them, but it would probably need to a PCB + programmed chip deal to mitigate the supply and programming issues.
 
I don't think that any of the Atmel parts are through-hole however. PLCC was a good compromise because you could use through-hole sockets or mount the package directly SMT-style. Well, you get the idea.
 
http://www.atmel.com/products/programmable-logic/spld-cpld/default.aspx:
ATF16V8/ATF22V10 - DIP/PLCC GAL replacements (~350 gates)
ATF750 - 750 gate CPLD in a 24-pin DIP or 28-pin PLCC
ATF2500C - 2500 gate CPLD in a 40-pin DIP or a 44-pin PLCC
ATF15xx series - 5V CPLD, 32-128 macrocells, available in 84-pin PLCC

The one big disadvantage I see with these parts is that the development tools provided are not as nice as provided by the other vendors.

John M. used the ATF1508 on the new S-100 386 board - http://www.s100computers.com/My System Pages/80386 Board-II/80386 CPU Board_II.htm
 
Interesting subject !!
I am currently working on something similar.
I try to install ( solder ) an ALTERA TQFP 100 ( EPF7128, pitch : 0.5 mm ) on an square adapter with 0.1" pitch.
Idea beeing : Having a "standard mount CPLD" available for different printed circuit / card designs.
I first looked at the 84- pin PLCC but infortunatly I was short by 6 / 8 pins for the first design :-(( ...
so I had to go TQFP 100.
My first three attemps were not good, but were improving each time. ;-)
Next attempt will be with : paste / stencil / regulated hot air gun.
Waiting for the stencils to arrive ...

I did not mention, but of course, it is a 5V logic design ;-)
 
Try some FL-22 flux and solder wick for any excess, they come up pretty good very easily :)
 
pearce_jj said:
Try some FL-22 flux and solder wick for any excess, they come up pretty good very easily :)
Click to expand...

I DID !! Last try : Fresh flux, fresh wick, carefully cleaned board ( gold plated !! ) .... but basically I had an aligment problem, mostly on one side ???.
You see, what needs to be more fresh is .... the operator ;-)
 
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You're not alone in fumbling with TQFPs. I've got a method that appears to work for me, even with a plain old TC soldering iron.

I first apply a bit of clear (although it probably doesn't matter--hot pink would work as well) fingernail polish to the underside of the package, and then use an inspection microscope to position the package accurately and allow the nail polish to cure (a little gentle heat speeds the process). I then "tack" each of the corner contacts in place with solder, then solder the remainder of the contacts and then clean up. For me, this seems to be foolproof.
 
Ha Chuck !!!
Great idea, the fingernail polish and waiting it cures !!!
I will try it as soon as I can.
Are you using a classic optical microscope or an "USB" device like I do ??? ( a bit sensitive :-( must have a day without coffee BEFORE using it !! )
BTW, I am still wondering how I could have got misaligment ( pins almost between tracks ) MOSTLY on ONE side and the three other side correct ??
 
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