Computermuseum der Fakultät Informatik				german

IBM 5110

Type:          5100 und 5110                           <<<    >>>    ^^^
Manufacturer:  IBM
Year:          1976
Technology:    TTL + MOS
Memory:        64K RAM
               >64K ROM
Price:         DM 27.000,- bis 57.000,-


In 1977, the IBM 5100 was the first  personal computer at the IfI. 
However, it was masked as an 'intelligent terminal' at the IfI annual
report, because the real computer was called TR440 at the time.
The 5100 was IBMs first try to introduce a personal computer, that 
means a computer, which could be put on the desktop. It was 
introduced in 1975. The specific is its concept, that everything
necessary is integrated in one case. Thus a 5" screen, a QIP tape 
drive, a keyboard as well as optionally a BASIC- or an APL-interpreter
(or both) are united with the central unit to a compact complete 
system. The main memory extension is 16 up to 64KB.
Nevertheless the computer is no lightweight:
The description "portable" simply provides an differantiation from the 
large systems, which were bound to a special location. As accessories,
there were two serial interfaces, an IEEE-488 interface, a matrix 
printer with optionally 80 or 120 lines per second and an other 
external tape drive deliverable. The only manufacturer was IBM, 
products from other companies for this computer are not known;
however, a Braille output line is existing, which can be connected
to the serial interface of this computer.
The computer works internally with full 16Bit, but the ALU with only
8 Bit. The processor is completely micro-programmed, where the 
microprogramm is stored in the so-called "Control ROS" 
(Read Only Storage). Additionally to the main memory (up to 64KB),
the computer owns some dozens of KB ROM (resp. IBMs ROS), where 
the monitoring program, the interpreters, the tables etc. are stored.
That's why the processor can adress alltogether more than 64KB. For 
not executionable ROMs and for the communication with the I/O-devices,
the computer has 16 specific device adresses.
The processor has four interrupt layers; Layer 0 is the normal program 
execution, the others are for the I/O-interrupts. Each layer has its 
own set of 16 registers each per 16 Bit, where register 0 is the 
program count. They are shown at the beginning of the main memory,
but are located on the processor card and are correspondingly 
fast.
By pressing a key on the front panel, the display can be switched, so 
instead of the normal output the first 512 Bytes of the main memory, 
that means also the registers in HEX-form during the operation can
be shown. In 1978, the IBM company introduced the successor of the 
5110, this time in two versions: the Model 1 and the Model 2.
It became a fact, that the capacity of a cassette wasn't very 
lusciously dimensioned with its 200KB. Additionally, the cassettes were
not compatible with other computer systems. Thus IBM disigned the new
series with a connection with 8" disk drives whose recording format 
was compatible with many IBM systems(and others), so the data change
was made possible in a simple way. The large capacity of up to 1,1MB,
the higher transfer rate and the free positioning of the heads made 
also possible to realize a real data processing and appications like 
storage lists, customer administrations etc with these computers, where
they were then used for. Correspondingly, the Modell 2 is equipped
without a tape drive, the external interface is not intended. Due to
the 5100 still uses own code, the punched tape code was changed to
EBCDIC at the 5110 also to ease the data transfer here.
However the IBM 5100 resp. 5110 were no bestsellers.
They were soon replaced by the IBM 5150, the IBM-PC.