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  • D3B_4323

Philips P859


Dimensions:48 x 27 x 55cm
Maximum memory size:512KW = 1MB
Maximum number of CPUs:1
uses architecture:P800
can contain:Philips CP7RA
System class:Minicomputer
  • rck_D3B_4321


CPU CP7RA, 16-bit CPU built around Am2900 slices
Memory 512 Kword (265KB) 21-bit ECC RAM
I/O Slots 10 GP Slots
Enclosure M4 (48cm x 27cm x 55cm, 6U)
Introduced 1980


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.


2 M128E 128Kword RAM
3 M128E 128Kword RAM
4 M128E 128Kword RAM
5 M128E 128Kword RAM
6 IOP First I/O Processor
7 MCU3 Serial port, paper tape reader and punch interface
8 MCU2 Card reader and line printer interface
9 CDD Cartridge Disk Drive controller
10 FM1B 8" Floppy Disk controller
CC K7S2 Cassette Drive controller (in cassette drive enclosure)

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

Philips P859 [R0280]


Philips P859 [R0313]


Contains:Philips CP7RA

Related articles

Acquired Philips P800 mini computer systems
Emulating an X1215 cartridge disc drive
Getting an X1215 cartridge disc drive online
Stepping and reading an X1215
Reading data from the drive
Reading 32-year old data off an X1215 disk pack
List of X1215 disk packs
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