IBM Multistation ("multi-function workstation") or IBM 5550 is
a series of personal computers aimed at business customers. It was developed
and marketed by IBM Japan in the 1980s and 1990s.
When the original IBM PC (5150) was released in the United States, it
very quickly became a de-facto standard in the personal computer market.
At the same time the switchover from 8 bits to 16 bits was taking off in Japan,
and some 16-bit personal computers of domestic production were already on the
market - Mitsubishi Multi-16, Hitachi MB-16000, Fujitsu FM-11, and NEC PC-9801.
IBM Japan also needed to put personal computers on the market. However,
in the personal computer of those days, unless it gave structure special
to a Japanese display, sufficient processing speed was not obtained.
Especially the big problem was the resolution of a display.
Unless 16x16 dots per character can be achieved, a Kanji can't be displayed
correctly. Therefore, with 640x200 pixels which is the resolution of
CGA of IBM PC were used, only 12 lines could be displayed on one screen.
By the Japanese maker, in order to display 25 lines of Kanji, the video
system with the resolution of 640x400 pixels was developed.
However, in IBM Japan, in order to display a Kanji by 24x24 dots, the video
system of 1024x768 dots was developed. Moreover, in order even for the Kanji
of 16x16 dots to give and display a margin, the video system of 720x512 dots
And as a result, it became hardware unique to Japan. Multistation and IBM PC
became non-compatibility. However, this poses a big problem later.
With the appearance of the Multistation, details after that
In 1983, IBM Japan introduced "The Multistation 5550" which is the model of
beginning of a Multistation series.
As series following "5550", "5540" as a low rank model and "5560" as a higher
rank model were added.
These models were mainly sold as an on-line terminal of the user who was using
the Main-frame and Mid-range of IBM.
But, as for Japan, a Japanese manufacturer occupied most market share.
PC-9801 which NEC sold specially occupied most of that in the family use.
When a personal computer was 8 bits, NEC and Fujitsu Ltd. and Sharp Corp.
were fighting as 3 big manufacturers. After that was 16 bit, it had been 1
strong condition of NEC.
IBM Japan competed with that, too, and sold 5510 (JX) which was the compatible
machine of the PC Jr. for the family use. But, this ended in failure.
IBM Japan and other Japanese manufacturers had market share with business
use to a certain extent, too. However, it is a fact that there was a limit
in the expansion of the market share, too.
Then, it was made a problem that a Multistation and IBM PC were
non-compatibility. It did because it thought that it obstructed the expansion
of the market share that hardware for IBM PC and software couldn't use it with
a Multistation the personal computer of IBM.
IBM proceeded with the development of PS/2 which a MCA bus was used for
as the next-generation machine of PC/AT. IBM Japan were developed the
next-generation machine of Multistation as the compatible machine of PS/2.
And it was named PS/55. 5570 which was the first MCA machine was put on the
market in 1987. The general term of the series was changed from the
Multistation to PS/55 at this time. 5535 which was a lap-top model with 5530
of the lowest rank model was added as a Multistation at the same time.
As for the new model following 5550-S/T/V after this, all became a MCA
machine. Then, every time a MCA machine was on the market, the machines of the
Multistation were put in order, and the machine of all the Multistations
disappeared in 1991.
Though this IBM continued the sales of PS/55 in this another day, it became
IBM PC in the latter half in the 199's, and PS/55 disappeared.
The sales of the MCA machine were stopped after that, too, and they became
only the specifications of the PC/AT compatible machine.
May, 2005 IBM transferred the personal computer enterprise to Lenovo, and
has withdrawn it from the personal computer.
The origin of the name of the Multistation
As for the Multistation, "one unit 3 post", in other words A Personal
Computer as to Japanese business Japanese word, processor The terminal of
Japanese on-line system A function is changed by one unit, it can be used.
At pays attention to the way of calling model name
When 5570 was sold, the name of the series was changed to
"The Personal System/55". The way of calling it settled in the head from this
time became the same "PS/55" with the MCA machine, and came to give the person
who didn't know a difference in two models confusion.
Incidentally, each affiliated model of the Multistation is as the following:
5550 A, B, C, D, E, G, H, J, K, M and P
5560 G, H, J, K, M and P
5540 B, G, J, K, M and P
5530 G and H
The model which L, N, R and the name of S, T, U, V, W, Y and Z are attached to
is a MCA machine. Multistation series and MCA machine series is perfectly
non-compatibility of the hardware.