# xDbg

xDbg is a 65C02 debugger meant to compliment the Corsham Technologies xKIM monitor.

## Features
* Pure 6502 code.
* Can load Intel hex files from either the SD card or console.
* Breakpoints without external hardware support.
* Single-stepping without external hardware support.
* WDC65C02 disassembler.
* Examine/edit memory.
* Can compute offsets for relative branches within memory editor.

## Command Summary (not a complete list)
* Examine/edit memory.
* Display/set registers.
* Jump to code.
* Load Intel hex file from console or SD card.
* Directory of SD card.
* Branch offset calculator, also within memory editor.
* Disassemble WDC65C02 code.
* Step/Step-over
* Breakpoints: list, set, clear, enable, disable.

xDebugger_Manual

Downloads:
xDbg for 65C02

Archive with SS-50 software

See also the Corsham github repositories for the latest versions of programs.

In this archive:

• 6800 programs

  xswtbug
  This is the extended version of SWTBUG, originally written by SWTPC and then enhanced by Corsham Tech. It is fully compatible with the original, and all entry points are the same, so old programs should run with it. This is the source file to the code in the EPROM on the 6800 CPU board.
  Note that this includes some low level functions for the SD card adaptor we’ve been working on, so that’s what some of the code is about.
  MicroBas

  This is Technical Systems Consultants’ (TSC) Micro Basic Plus, a 4K BASIC interpreter. This has been modified so the user can build it for use with either the MP-C card (as delivered) or the MP-S card (our change). The S19 file is built for the MP-S (or
  compatible card such as our serial board). It can be loaded with SWTBUG’s L command.
  numguess
  A silly number guessing game I wrote one evening, based on an interview question at Microsoft in the mid 1980s. Read the comments for an explanation. Basically, guess a number between 1 and 100 but it involves some rewards or consequences.
  console.asm
  I wanted a stripped down set of input/output functions for the console, and also a kbhit function to determine if a key is waiting or not, so this file was tossed together. It only supports ACIA boards, not the MP-C. Other source files include this.
  othello
  This is a decent version of the Othello game taken from the internet. We did nothing except make it assemble with the AS02 assembler.
  memtest
  A decent little memory test program that prompts the user for the starting and ending location, then does a rolling nine bit pattern. Since the pattern repeats every nine bytes (as opposed to a power of two), it can detect shorted address busses and the like.
  A “hunt the wumpus” game I found on the net. It assembles and runs, but that’s as far as I’ve tested it.
  Life.
  Don’t speak to me about life.” (you should know the reference).
  This is a version of Conway’s Life program, although it has bugs. One know issue is that it scrolls the screen when using a WYSE-30 terminal, so the whole screen is off by one row; makes updates look odd. Might have other bugs too. You can assemble it for either VT-100 or Wyse-30 terminals.

• 6809 programs

  This contains 6809 related software. Sorry, but the 6809 board took a lot longer than anticipated, so there wasn’t much time to develop fun software like we did for the 6800 board.
  sbug_1_8 is the basic 6809 debugger that SWTPC included on their 6809 board. This is modified to build with the Kingswood Consulting 6809 cross assembler AS09.
  sbug is our more modified version that has options for building a Tiny BASIC into the lower 2K.
  basic is the Tiny BASIC interpreter

• SBUG 1.8.1

  (see github for 1.8.2)

• xSWTBUG

  ;REPLACEMENT FOR MIKBUG ROM
  ;FOR SWTPC 6800 COMPUTER SYSTEM
  ;COPYRIGHT 1977
  ;SOUTHWEST TECHNICAL PROD. CORP.
  ;AUGUST, 1977
  ;***************************************************
  ;
  ; Enhancements by Bob Applegate, K2UT
  ; bob@corshamtech.com
  ; www.corshamtech.com
  ;
  ; This was all done for the SWTBUG included with the
  ; Corsham Tech 6800 CPU board.
  (see also github)

• CTMon65

  Monitor for the SS-50 65C02 CPU board
  (see also github)

This is the coolest thing we’ve done… so far!

Our original 6800 board continues to be a fun project to work with. I grew up doing 6502 and Z80 assembly language and have always been able to do a lot with either, but the 6809 is just amazing! The instruction set and addressing modes make it easy to write much more complicated code. There are numerous operating systems for this processor, include multi-tasking and multi-user options.

Features
– 68B09 processor running at 2 MHz.
4- K EPROM – SBUG occupies upper 2K, and the lower 2K is available. We usually put either a Tiny BASIC or SD card subroutines there, but it can be replaced with user code.
– Switch allows disabling the lower 2K of the EPROM.
– 128K RAM – Extended memory banks 0 and 1. Each 8K block can be enabled/disabled via easy to use DIP switches.
– Support for the extended 20 bit address bus using the same Dynamic Address Translation (DAT) as the original SWTPC board.
– Jumper selection of either baud rate clocks or address bits for A16 to A19.
– Jumper selection of either baud rate clock or /BUSRQ line.
– On-board RESET button along with headers for external reset and interrupt buttons.
– High quality dual-layer board.
– Off the shelf components: easy to understand, easy to repair, easy to modify.

This shows the jumpers used to select the extended address lines or baud clocks, and clock selection. The jumper block labeled VAR sets the “VAR” clock rate to 1200, 2400, 4800 or 9600 baud (actually x16). The VAR/BUSRQ jumper selects which of those two signals are placed onto bus pin 46, usually the 110 baud clock line.

The other four jumpers select whether A16 to A19 or additional baud rate clocks are placed onto pins 47 to 50. The usual practice is to use all four lines for the extended address bus, then use pin 46 (110 baud/BUSRQ) as the clock for the serial board:

SS-50 6809 CPU Manual

Archive with older revisions (2-5) schematics