Pentasonic PROF 80 computer

All material on this page is contributed by Mr. Pascal Holdry, France. Mr. Holdry obtained permission to publish the documentation and firmware for non-commercial purposes.

The Pentasonic PROF 80 was sold in France as bare board. It was a TRS-80 model I clone, with a partial Expansion Interface logic integrated into the main board. The 12kByte Basic is the same as the LNW Basic ROM (which is the TRS-80 Basic, with some instructions replaced by functional equivalent ones).

PentaSonic advertisement Special PROF 80

PentaSonic advertisement Special PROF 80

Its features are:

Main PROF 80 board

PentaSonic PROF 80 main board

PentaSonic PROF 80 main board

Several options were listed:

Hificolor graphics board

PROF80 graphics board

PROF80 graphics board "Hifi Color"

The EF9365/EF9366 Graphic Display Prcessor on which the HifiColor is based, has the ability to draw straight vector lines on the screen from a specified starting coordinate and horizontal and vertical deltas. There are four patterns for the line. Another capability is printing characters from a fixed set in four modes; normal (horizontal), normal slanted, vertical (upwards), vertical slanted. There is also light pen support.

The Hifi color card is accessed via a Basic extension GBASIC.

Hifi Color GBASIC demo

Pentasonic GBASIC demo on Hifi Color board

CP/M adapter

The CP/M adapter card contained a 2 kByte ROM with a boot menu. Two option levels are implemented:

PROF80 CP/M adapter card

PROF80 CP/M adapter card

Options were selected by single key strokes, similar to the Omikron Mapper. The boot-ROM also contained detailed error messages if booting failed. This board also works in a regular TRS-80, but without the 16 kByte shadow RAM, so 48 kByte RAM.

Bit 0 of several ports is used to switch the memory map:
F8h (248)0 - Boot1 - Normal
F9h (249)0 - BASIC at 0000h-2FFFh1 - shadow RAM at 0000h-2FFFh
FAh (250)0 - CP/M mode1 - TRS-80 mode (DOS)

Most of the switch logic is on the CP/M adapter but some (ROM/shadow RAM) has to be on the main PROF80 board.

Local links:

External links:

More documentation in the documentation directory.

Last update: 2014-06-09