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IBM slot limitations

Roland Huisman

Roland Huisman

Veteran Member
Joined
Mar 24, 2011
Messages
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Location
The Netherlands
Hello Everyone,

I thought I'd once read something about a limited use for a PC XT slot.
It seems not al cards work in the slot with the circle.
Can anyone tell me what the limitations are?

slot limitations.jpg

Regards, Roland
 
It's due to wiring differences in the first slot so it could be connected to a mainframe computer. Don't know the specifics of it, though. I think IBM made a special serial card to go into that slot.
 
Ahh wonderful, thanks for the information! I thought I'd read
something about it but I was not sure any more.

I've an overloaded PC XT and I thought let's swap the card
with the lease significant card, the RS232 card. So this card
can stay but what else can you throw out...
Soundblaster, NE1000, parallel + serial 2, memorycard :sad:

For now the parallel + serial 2 has to leave.

overload.jpg

It's time for me to find an 5161 somewhere. Not ebay... :shocked:

Regards, Roland
 
SpidersWeb said:
Cards like the AST SixPakPlus are good, get ports + clock + RAM all in one slot.
Click to expand...

I have a "7 Plus" card in my 5150, which is floppy controller + 2 serial + parallel + game port + clock. (The advertised 7th function was printer spooling software which it came with.)
 
Oh that's a good idea! If only the extra memory and
I/O ports are on one card I would be out of troubles :)

What is the function of the clock on these cards?
There is a clock in the machine itself. Or are there
more options like alarm settings?

Regards, Roland
 
Think of it as a 'battery backup time and date' - it's so you don't have to enter the time/date each time you turn the machine on.
AST drivers for it are easily found on the web. 5150/5160 just assume it's 1980 until you tell them otherwise.

The AST SixPakPlus cards take a coin battery, so easily replaced too.
 
Hello Roland,

I couldn't resist commenting on the sweet looking XT you have there. I was curious though, I couldn't make out the type of card in slot 1.
 
Roland Huisman said:
I thought I'd once read something about a limited use for a PC XT slot.
It seems not al cards work in the slot with the circle.
Can anyone tell me what the limitations are?
Click to expand...

Because of signalling problems with that slot, cards in that slot have to have the card_present line. Examples are the IBM Serial Adapter (the card found by default in an IBM PC XT out of the factory) and the short IBM 3278/79 Emulation Adapter.

modem7 said:
That is speculation, not established fact.
Click to expand...
Its shouldn't even be speculation because I'm afraid that it's incorrect. There is no need for special slot for connecting to a mainframe. Any old slot will do (other than as above) with the appropriate adapter card: Serial Adapter, BSC Adapter, SDLC, Adapter or (via a control unit) 3278/79 Adapter.
 
Last edited:
fatwizard said:
Hello Roland,

I couldn't resist commenting on the sweet looking XT you have there. I was curious though, I couldn't make out the type of card in slot 1.
Click to expand...

Hello, this card is the soundblaster CT1320.
The card I wanted to add is the interface card for the CM100 CD-rom.

Regards, Roland
 
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