65C02 SBC

A single-board computer built around the Western Design Center W65C02S processor — the modern CMOS successor to the classic 6502. Designed to be compatible with OSI Superboard / Compukit UK101 software from 1979.

Specifications

• Processor: W65C026TPG-14 (or R65C02P) — 14MHz CMOS 6502
• RAM: 32K × 8 (Hynix HY62256B)
• ROM: 32K × 8 EPROM (NM27C256Q)
• Serial: MC6850 ACIA — 19200 baud (4MHz crystal) or 38400 baud (8MHz crystal), 8-N-1
• Expansion: 36-pin right-angle bus connector

Note: CAPS LOCK must be ON when using a terminal. On power-up you will see: CEGMON..... A/B/C/E/M/W?

Memory Map

Address	Contents
$0000–$7FFF	32K Static RAM
$8000–$87FF	ACIA Control & Status Registers
$8800–$8FFF	Unused
$9000–$FFFF	32K EPROM

Pre-loaded EPROM Contents

Address	Software
$A000–$BFFF	Microsoft BASIC (1979, as supplied with OSI Superboard / UK101)
$C000–$D23F	Spare ($FF)
$D240–$DFFF	OSI 6502 Assembler
$E000–$E7FF	OSI Extended Monitor
$E800–$F7FF	Spare ($FF)
$F800–$FFFF	Cegmon V2 Monitor (modified for serial terminal)

The software supplied is not being sold — I have no legal right to it.

Bill of Materials

Ref	Part	Description
IC1	W65C026TPG-14 / R65C02P	CMOS 6502 14MHz Microprocessor
IC2	MC6850	ACIA (Async Comms Interface Adapter)
IC3	NM27C256Q	32k×8 CMOS EPROM
IC4	HY62256B	32k×8 CMOS Static RAM
IC5	SN74LS00	Quad 2-input NAND Gate
IC6	SN74LS11	Triple 3-input AND Gate
IC7	SN74LS14	Hex Schmitt Inverter
IC8	74LS74	Dual D-Type Flip Flops
IC9	HD74LS138	1-of-8 Decoder
IC10	M74LS163	Synchronous 4-bit Counter

Each IC requires a 0.1µF decoupling capacitor.

36-Pin Bus Connector

Left to right: D7 D6 D5 D4 D3 D2 D1 D0 A15 A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 CPUCLK PHI2 CPURW CPURESET RAMRW ROMOE ACIACLK /2MHZCLK GND RX TX 5V

Downloads

• CEGMON Binary (serial version)
• CEGMON + Floppy Disk Bootstrap
• OSI Assembler & Extended Monitor Guide (PDF)
• UK101 Manual (PDF)
• CEGMON Manual (PDF)

Schematics & Images