IBM 5160 with oddball MDA input/output card

[Paul Berger]

On 2019-07-26 4:53 p.m., Fred Cisin via cctalk wrote:
> On Fri, 26 Jul 2019, Jules Richardson via cctalk wrote:
>> Someone on one of the Facebook vintage groups found an IBM 5160 with 
>> an MDA display for sale in Australia, except that it's a bit odd in 
>> that the machine had what appears to be an MDA card, the output of 
>> which is then connected via a short external cable to the input on 
>> another card, and then an output that card is what's actually hooked 
>> up to the monitor.
>>
>> The only internal photo of the machine is very poor, unfortunately. 
>> I'm reasonably confident that the "first" card in the "mystery" chain 
>> is MDA, it's full-length and alongside the DE-shell video output has 
>> the usual DB-25 for parallel. The "mystery" card is also full-length, 
>> and there's another full-length card immediately adjacent to it with 
>> no external connectors - that one could easily be RAM, or the hard 
>> disk controller etc.  but I suppose it's possible that the mystery 
>> item is actually a two-card set.
>>
>> Anyway, any guesses as to what it might be? The implication is that 
>> the mystery card adds functionality to the MDA card (reminiscent of 
>> 3DFX boards years later), but of course is operating within the 
>> confines of what the MDA display's capable of.
>
>
> Genlock?
> MOST video add-ons were combined onto a board with their own video 
> card, rather than connecting to IBM's
>
> Co-processor?
>     Diamond Computer Trackstar was an Apple2 on an ISA card. It was 
> even sold [briefly] by Radio Shack.
>     Quadram Quadlink was an Apple2 on an ISA card.  The college bought 
> 20 of them.  14 were DOA.  8 of the replacements ("THESE ones are 
> thoroughly tested") were also DOA.  One had a connector (right angle 
> dual row?) mounted backwards, and could not be connected for testing.
>
> But, MDA (or MDP as described) seems less likely.  "Who would want to 
> do Visicalc or word processing without COLOR??"  There did exist a few 
> after-market CGA cards that had DE9 and DB25 (printer).
>
>
> Was it in working order?  Or had somebody merely cabled the MDA video 
> to a DE9 serial port?  And 5151 will physically connect to CGA (and 
> not work)
> We had a couple of "instructors" at the college who didn't see 
> anything wrong with connecting any cables that fit, including swapping 
> bus mouse and video, or wanting gender changers to try to connect a 
> parallel printer to a 25 pin serial port ormodem to printer port.   It 
> is frustrating to try to deal with some people.

I know of a "trained" service technician who inserted an PCI card into a 
ISA card slot and then call for assistance because it did not work.    
Fix.. swap technician...

Paul.