SIMPLE-6502

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CPU-65C02 REV1 FRONT (BLK).png

Features

  • Build of Grant Searles's Simple 6502 CPU
    • Runs Microsoft (OSI) BASIC
  • 6502 CPU
  • 0.9216 or 1.8432 MHz clock
  • 32KB SRAM
  • 16KB EPROM/EEPROM
  • 68B50 Serial Port (ACIA)
    • RS-232 port
    • Header for FTDI
    • 115,200 baud
  • Reset switch with optional Power Supervisor
  • 95x95mm card
  • (4) 6-32 mounting holes

Memory Map

  • 0x0000-0x7FFF 32KB SRAM
  • 0x8000-0x9FFF Free Space (8KB)
  • 0xA000-0xBFFF Serial (ACIA)
  • 0xC000-0xCFFF 16KB EPROM

Chip Set

LB 65C02 PARTS.jpg

  • Used these parts:

SIMPLE-6502 P1090155-720px.jpg

References

Design

  • CPU

U5 CPU 6502.PNG

  • EPROM/EPROM

U4 EEPROM.PNG

  • SRAM

U2 SRAM.PNG

  • Clock

U7 U8 CLOCK.PNG

  • UART

U1 U3 UART.PNG

  • FTDI

J3 FTDI.PNG

Headers / Connectors

SIMPLE-6502 REV1 CAD.PNG

J1 - RS-232 Serial

  • DB-9 Male
  • Pinout
  1. N/C
  2. Receive
  3. Transmit
  4. Loop to pin 6
  5. GND
  6. Loop to pin 4
  7. RTS
  8. N/C
  9. N/C

J2 - Speed Select Jumper

  • 1-2 - 0.92 MHz
  • 2-3 = 1.8432 MHz

J3 - FTDI / TTL Serial

  1. GND
  2. RTS* (out)
  3. +5V
  4. Receive (in)
  5. Transmit (out)
  6. N/C

J4 - 5V Power

  • 2x4 header

J4 PWR-5V.PNG

J5 / J6 - EPROM/EEPROM Select Jumpers

SIMPLE-6502 J5 J6.PNG

27512 27256 28C256 27128 2764 28C64 PIN PIN 2764 28C64 27128 28C256 27256 27512
A15 VPP A14 VPP VPP N/C 1 28 VCC VCC VCC VCC VCC VCC
A12 A12 A12 A12 A12 A12 2 27 PGM WE* PGM WE* A14 A14
A7 A7 A7 A7 A7 A7 3 26 A13 N/C A13 A13 A13 A13
A6 A6 A6 A6 A6 A6 4 25 A8 A8 A8 A8 A8 A8
A5 A5 A5 A5 A5 A5 5 24 A9 A9 A9 A9 A9 A9
A4 A4 A4 A4 A4 A4 6 23 A11 A11 A11 A11 A11 A11
A3 A3 A3 A3 A3 A3 7 22 OE* OE* OE* OE* OE* OE*
A2 A2 A2 A2 A2 A2 8 21 A10 A10 A10 A10 A10 A10
A1 A1 A1 A1 A1 A1 9 20 CE* CE* CE* CE* CE* CE*
A0 A0 A0 A0 A0 A0 10 19 D7 D7 D7 D7 D7 D7
D0 D0 D0 D0 D0 D0 11 18 D6 D6 D6 D6 D6 D6
D1 D1 D1 D1 D1 D1 12 17 D5 D5 D5 D5 D5 D5
D2 D2 D2 D2 D2 D2 13 16 D4 D4 D4 D4 D4 D4
GND GND GND GND GND GND 14 15 D3 D3 D3 D3 D3 D3

JP1 - CPU Pin 1

  • Install if CPU is not a WDC 65C02 or WDC 65C816

Software

  • Link to Grant's files
  • Source code
    • osi_bas.s <== the Microsoft OSI BASIC and I/O routines SOURCE all in a single file. My I/O routines are at the end of it.
  • Files to allow the source to be assembled on a Windows based machine
    • assemble.bat <== double click to assemble osi_bas.s and link to binary file "osi_bas.bin". This should be exactly 16K
    • osi_bas.cfg <== configuration file for the linker (ensure ORG and entries in this file match if you change any)
    • ca65.exe <== the assembler from the cc65 package. Use this. The new version on the cc65 site crashes!
    • ld65.exe <== linker from the cc65 package
  • Output files
    • osi_bas.bin <== the ROM fine in pure binary
    • osi_bas.lst <== Assembly listing file
    • rom.hex <== the ROM fine in standard INTEL-HEX format
  • To allow simple re-assembly, extract all files to the same folder
    • Freeware utilities are available to convert the "bin" file to HEX or s19 (etc) - use your internet search tool to find
  • All source code, assembler binaries and the HEX dump of the ROM is here
    • It is in standard INTEL-HEX format for uploading to a suitable programmer.

Mechanicals

SIMPLE-6502 REV1 MECHS.PNG

Checkout

  • SST27C256 EEPROM
    • 32 KB part
    • Using first 16KB of EEPROM
    • Program using TL-866ii plus programmer
    • File = ROM.hex
    • J5 EEPROM pin 1 = VPP = VCC or GND
      • Jumper J5:2-3
    • J6 EEPROM pin 27 = A14 = GND
      • Jumper J6:2-3

Assembly Sheet