The P75 was a released in 1990 upgraded version of P70 model, and is noted as being the first
portable computer using a
486 CPU to be available for sale in the United States. It had a briefcase-shaped design and ran off A/C power only, as was common with high performance portable computers at the time. It featured an
Intel 80486 DX-33 CPU, and an internal 10-inch flat gas
plasma display at 640x480 resolution with 16 shades of grey. The computer had relatively high performance specifications at the time it was released and could be used as a portable
server. The cost reflected this performance; the IBM P75 retailed at US$15,990 for the base configuration, to over $18,500 or more depending on options. Two versions of the P75 were sold, with the only difference between the two being hard drive capacity:
Hardware The IBM P75 has similar specifications to an IBM model 90, but has been made into a portable. It features an Intel i486-DX 33 CPU that is housed on a processor complex card separate from the motherboard. The computer uses IBM's
Micro Channel architecture (MCA) bus and has 4 internal bus slots: one 32-bit AVE, one 32-bit MME, and two 16-bit short slots. The internal gas plasma display of the IBM P75 is
XGA/VGA,
EGA,
MCGA,
CGA compatible, and operates at a maximum 640×480 in 16 shades of grey in
VGA mode. The IBM P75 can drive its internal monitor and an external monitor simultaneously. When driving the external monitor only, it can operate at 800x600 resolution in 16-bit (
high-colour) in
Windows 95 using third party drivers. The keyboard is a 101 key, full size and full travel IBM keyboard and serves as both the keyboard of the unit and the cover of the unit when being transported. It is attached to the computer through a 14-inch rolled-coil cable. The IBM P75 featured numerous ports, including an external
SCSI connector, a
parallel port, a
serial port, a
PS/2 mouse port, an external 5.25" floppy disk port, and a
VGA port. The ports are housed behind a door on the rear of the unit which allows for them to be hidden when not in use. The recess behind the door can also be used to store a power cable during transit. Power is supplied to the IBM P75 through an IEC
C14 socket, the
PSU accepts 100-240v 3.0A
Software The IBM P75, like other contemporary PS/2 computers of the period, utilises reference diskettes to make any changes to system settings such as the installed memory size, the assignment of the built-in connectors, and installed options with their location and assignments. System settings are stored in
CMOS and data integrity is maintained through an internal non-rechargeable 6V battery. Should the internal 6V battery run low, the computer may not
POST successfully as the internal
CMOS contents are corrupted. The reference diskette also includes basic diagnostic software. If the computer is booted without an operating system and/or hard disk, the P75 will boot into IBM
Cassette BASIC. IBM did not ship with any additional operating system, but is fully compatible with
OS/2,
AIX,
MS-DOS,
IBM PC DOS and
Microsoft Windows. == References ==