Patrick Computer Systems IC436 information

Patric Computer Systems, INC. was a canadian computer company from Winnipeg, Manitoba. They produced at least one S-100 bus based computer. At one time it was marketed as "The Lepraucaun". Most of the documentation refers to it with the less prosaic name of IC436.

This S-100 bus, multi-processor CP/M system from the early 1980's seems to be targeted at some sort of desktop publishing (based on the extra keys on the key-board). It is multi-processor in the sense that each I/O-board had its own Z80 CPU and DMA-accessible 16 kByte RAM.

An article in Canadian Business reader from 1986 mentions that about 100 IC436's were build.

The system documented here was found in southern Wallony, Belgium. It is now located at the premises of Jaak Bartok. There are cautious plans to get it back to working order.

Company Patrick Computer Systems, Inc. logo The generic internet has next to nothing on Patrick Computer systems, but delving into archive.org does result in advertisements between 1979 and 1982. They had subsidiaries like KIT-80 INC. which sold an 'E-Z-80 ENTRY KIT' or TRS-80 memory upgrades. In these ads the proudly mentioned PCS is the manufacturer of the "IC436 integrated business computer". In the November, 1982 Electronics Today International magazine they advertised with bargain boards taken from the IC 436 computer.
The company was located at 11 Plymouth Street, Winnipeg, Manitoba R2X 2V5 and founded in 1978. The principals: Robert Patrick, Chairman & C.E.O., Robert Sutherland, President & C.F.O., Bruce Maunders, Vice President Engineering.
Products available: Digital microcomputers. Each computer is shipped complete with integrated application programs for: Word Processing, Accounts Receivable, General Ledger, Inventory, Accounts Payable, Mailing Lists.
See History by delving into archive.org for some more information.
Case Frame containing the CRT and space for four 5 1/4 inch floppy drives
keyboard unit
The frame contains a small ? " CRT screen and mounting space for four 5 1/4" floppy drives. Both the keyboard and Daisy Wheel printer are integrated in the case.
CPU
Block diagram CPU board
Z80 CPU, two Z80 CTCs (missing on the photo) and a boot EPROM (2 kbyte). The CTCs are used to generate vectored interrupts from the other boards. The Z80 CPU is always bus master and runs in Interrupt Mode 2.
Most components are not soldered, but make use of special board integrated IC sockets.
All communication between the CPU board and the other boards (except the Memory board) is via a few I/O ports.
I/O ports used:
  Z80-CTC U2    68h-6Bh (/VI0 - /VI3)
  Z80-CTC U7    64h-67h (/VI4 - /VI7)
  /MDIS         6Fh
Memory
MB64

Block diagram memory board
Intel D8202A memory controller and 4 banks of 16 kByte dynamic RAM.
FDC
FDIB

Block diagram floppy disk controller board
Z80 CPU, EPROM (2 kByte), Intel P8272 Floppy Disk Controller, Intel P8257 DMA Controller, 16 kByte dynamic RAM.
I/O ports used:
  FDIB status            23h
  FDIB data read         24h
  FDIB data write        25h
Video VDB80
Block diagram video board
Z80 CPU, EPROM (1 kByte), Intel P8275 CRT Controller, Intel P8257 DMA Controller, 16 kByte dynamic RAM.
I/O ports used:
  VDB80 handshake/status 13h
  VDB80 data read        14h
  VDB80 data write       15h
Keyboard/
Printer
port
PKIB

Block diagram printer/keyboard board
Z80 CPU, EPROM (1 kByte), parallel ports for keyboard and daisy wheel printer and 16 kByte dynamic RAM. I/O ports visible by main CPU:
  PKIB status out     10h (bit 0 and 2)
  PKIB data out       11h (8 bits)
  PKIB data in        12h (8 bits)
A partial disassembly of the ROM reveals very little actual code, only 191 bytes. The PKIB processor is operated in Mode 1, and depends on the CPU board for the code for most of its functionality. The PKIB I/O map. Also see the partial disassembly.
SIB
board
Serial / parallel board The SIB board was not a part of the original configuration, but a later enhancement to the system configuration. With two Z80 SIO/2 ICs and a Z80 PIO it would mean up to four serial ports and one parallel port.
IC sockets Board integrated IC socket, component side view
Board integrated IC socket, solder side view
What first appeared as partly unpopulated boards, was actually a special type of IC socket, fully integrated into the board.
Backplane Patrick Computer Systems IC436 backplane and floppy drive power supply As is customary for S-100 bus systems, all boards regulate their own power. The backplane here contains the regulators for +5V and +12V volt for the floppy drives.

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Last update: 2025-05-19