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.

Computer 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' (an single board computer) 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 had a advertisement with bargain boards taken from the iC 436 computer.

Company 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
The frame contains a 12" 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
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
Based on an incomplete inventory of the EPROM contents of the various boards, it looks like the FDC board EPROM is the only one containing routines needed for basic operation. Both the Video board and the Printer/Keyboard board rely on the CPU board for routines normal operation. The CPU board has just enough code to instruct the FDC board to fetch Operating System code from floppy. And all operational code for the Video board and Printer/Keyboard board.

Memory
MB64
Intel D8202A memory controller and 4 banks of 16 kByte dynamic RAM. This board is the only one exposing more than a few I/O ports to the S-100 bus. Memory is organized as a 16k Byte bank and a 48k Byte bank. A system with multiple memory boards (up to four) could use the 16 kByte bank as common memory and several 48 kByte banks. A fifth 48 kByte bank is made up of the other three 16 kByte banks.
Port FFh bits 0-2 are used for bank switching.

FDC
FDIB
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
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
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. This is based on the PKIB I/O map and the partial EPROM disassembly.

SIB
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. This board was part of the multi-user configuration.

IC sockets
What first appeared as partly unpopulated boards, was actually a special type of IC socket, fully integrated into the board.

Backplane 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.

Local links:

Generic links:

Archive.org for now Archive.org is the main information source on PCS.

e-mail

Last update: 2025-06-18

Computer		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' (an single board computer) 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 had a advertisement with bargain boards taken from the iC 436 computer.
Company		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		The frame contains a 12" 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		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 Based on an incomplete inventory of the EPROM contents of the various boards, it looks like the FDC board EPROM is the only one containing routines needed for basic operation. Both the Video board and the Printer/Keyboard board rely on the CPU board for routines normal operation. The CPU board has just enough code to instruct the FDC board to fetch Operating System code from floppy. And all operational code for the Video board and Printer/Keyboard board.
Memory MB64		Intel D8202A memory controller and 4 banks of 16 kByte dynamic RAM. This board is the only one exposing more than a few I/O ports to the S-100 bus. Memory is organized as a 16k Byte bank and a 48k Byte bank. A system with multiple memory boards (up to four) could use the 16 kByte bank as common memory and several 48 kByte banks. A fifth 48 kByte bank is made up of the other three 16 kByte banks. Port FFh bits 0-2 are used for bank switching.
FDC FDIB		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		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		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. This is based on the PKIB I/O map and the partial EPROM disassembly.
SIB 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. This board was part of the multi-user configuration.
IC sockets		What first appeared as partly unpopulated boards, was actually a special type of IC socket, fully integrated into the board.
Backplane		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.