IBM 5161

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Apr 2 18:07:24 2003

> On Tue, 1 Apr 2003, Bill Allen Jr wrote:
> > The ibm 5161 expansion box was designed for use with
> > the ibm pc.
> > the exp box added a hard drive to the system and
> > provided extra card slots ( i think the box also had
> > additional bios or came with an extra fixed disk rom
> > chip that went into the pc).
> NOT for the hard disk.

AFIAK there is no extra BIOS ROM for the expansion box.

> > i cannot remember if it is slot specific or if it can
> > go into any slot - there is a plate on the pc's back
> > that removes to allow the ribbon cables to exit the
> > case.

The Extender crd that goes into the PC has a DC62 connector on the
bracket. There's a similar one on the Receiver card in the expansion
unit. You link them with a (round) cable. There are no ribbon cables
involved, nothing comes out through slots in the PC case.

>
> The slots on the PC are wired in parallel. There is NO electrical
> difference between them, other than physical distances.

Correct.

> But in the XT, one slot is different. At the time of the release of the
> XT, IBM was worried that people would use that slot for something
> incompatible, and they had a giant surplus of serial (RS232 and current
> loop) cards that nobody wanted, so they provided a "FREE" serial card to

Why did 'mobody' want them? A serial port is a very useful thing to have...

> block off that slot.

One of the most stupid things IBM ever did was in the 5155 PortablePC.
That machine has a standard PC/XT motherboard in it. Alas the case is
just too short (about 1/2" too short) to allow the Async serial card to
fit in the special slot 8. Which means that slot 8 is essentially useless
in that machine.


> I think that the 5161 CAN be used on an XT, if eight is not enough.

Correct, it can. It also works on the 5155 'PortablePC', and is the only
offical way to put a hard disk on that machine. I guess it was a kind of
early 'docking station' :-)

AFAIK it _doesn't_ work on the 5170 PC/At, even if you only want to put 8
bit cards in the expansion unit. Pity....

-tony
Received on Wed Apr 02 2003 - 18:07:24 BST