Philips P859

Characteristics

Description

The Philips P859 was part of the third and last generation of minicomputers in the P800 family. While other systems of this generation are built on double-euro-size cards (200 x 160 mm), the P858 and P859 are built around the older large square card format with the GP bus in the middle. My guess is that this was done to let customers preserve their investment in I/O cards.

I believe that the difference between the P858 and P859 was that the first used core memory and the latter uses MOS RAM. The P858/P859 reference manual doesn't describe the differences anywhere, but there's a table in section 1.15 that lists memory options and their applicable system. P858 is listed against all core memory modules, and P859 against all MOS memory options.

The P858 and P859 have an expanded memory management unit built into the CPU, that allows up to 512 Kwords of memory to be addressed (the Philips P857 with its MMU could address up to 128 Kwords). This requires 2 extra address lines on the GP bus, which need to be added using wire wrap technique for those cards that need it.

My P859 enclusure is filled with the maximum of 10 cards. I don't have a floating point processor. The P859 is connected to the following peripherals:

• Serial console
• X1215 cartridge disk drive
• X1215 emulator (PC + FPGA based)
• P830-010 enclosure with 2 8" floppy drives
• P833 enclosure with 3 cassette drives

The picture of the entire rack shows (from top to bottom): 2 8" floppy drives, 3 cassette drives, P857, X1215, control panel for emulated X1215, P859.

Modules

Read about this system's acquisition here: Acquired Philips P800 mini computer systems.

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