Corsham projects, a tribute to Bob Applegate

Bob Applegate designed and sold for many years boards of interest for KIM, AIM 65, SYM-1 and the SS50/SS-30 users, his one man company was called Corsham TEchnology.

That ended last year when Bob died, and I miss him. A good friend with whom I exchanged many emails about the KIM-1 and KIM Clone.
I have bought many of his fine products. And many others did also, and due to the open nature of his projects, many variants appeared build by others.

His webpages disappeared in July 2024. His family does not respond to attempts to contact about the legacy of Corsham, many of us tried.

Therefore I decided to duplicate here all I have of Bob’s projects, in a way that makes it more accessible than his webshop sale pages, Github, private email exchanges and older downloads.

Here it is: Corsham Bob Applegate projects.

Enjoy, enhance, duplicate, and keep Bob in our memories, I claim nothing, I do not sell any Corsham product, I do not have more information like gerbers, PCB designs.
This is all Bob ever published!

xDBG for 65C02

# 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

KIM programs

Downloads:
KIM Programs

– Farmer Brown
– Lunar Lander
– Sample extension for XKIM

;=====================================================
; A sample extension for the Extended KIM monitor.
; This is a very simple example of how to write an
; extension (adding a new command) for the
; Extended KIM monitor.
;
; How can you test this? Easy. First, use the “?”
; command in the extended monitor and verify the
; “Z” command is not listed, then load the binary
; version of this file. Do “?” again and you’ll see
; the new command has been added and can be used.

Memory test

;***********************************************************
; This memory test was originally based on Jim Butterfield’s
; memory test program in the First Book of Kim, but has
; grown a bit.
;
; This now tests every memory location using a rolling 9-bit
; pattern. Ie the pattern repeats every 9 bytes, so this
; will detect most shorted address line problems. I use
; this to test memory boards, so it will run forever unless
; an error is detected. At the end of each pass, a ‘.’ is
; printed.
;
; This does output to the TTY port, so if you’re only using
; the default KIM display, the output functions will need to
; be tweaked. Not hard to do, but I didn’t need it.
;
; Written February 2006 by Bob Applegate, but it uses some
; bits of code from Jim Butterfield, and Ross Archer
; (http://www.6502.org/source/io/primm.htm).
;
; bob@applegate.org
; www.k2ut.org – look for my KIM page
;
; Rev 1.0 – 02/02/2006

Downloads:
Memory test for the KIM-1

SS-50 65C02 CPU Board

As many of you know, I started my journey in microcomputers with a KIM-1 in 1978 which was a 6502 based system. My next machine was an OSI SuperBoard, then an Atari 800, and Apple ][, and my first full-time job was at Franklin Computer Corp where I spent most every day doing 6502 programming., etc.

There was at least one commercial board for the SS-50 bus with a 6502, but it was never very popular. Given my interest in this processor I decided to create my own CPU board:

Basic specifications:

  • WDC65C02 processor running at 2 MHz. This is a genuine WDC chip, nothing with an unknown history that came from who knows where.
  • Full memory map of RAM. 0000-7FFF is always RAM while each 4K block in the upper 32K can be turned on or off.
  • EEPROM from F000 to FFFF.
  • Optionally, EEPROM can be enabled from E200-EFFF via a DIP switch.
  • We include a 28C64 (8K) EEPROM with CTMON65, but the socket can support 32K EEPROMs and two jumpers select which 8K region is visible.
  • A single-step switch is on top of the board. When an opcode fetch occurs outside of the EEPROM, an NMI is generated. Great for writing a single-step monitor.
  • The baud rate generator products x16 clock for 1200, 2400, 4800 and 9600 baud.
  • Power-on reset.
  • The monitor source code CTMON65 is available on our Github repository

This is an experimenter’s board as there was no code that I am aware of for a 6502 on the SS-50 bus. It uses the standard SS-30 I/O bus and most of those devices have plenty of example code for the 6800 and/or 6809 to use as templates for writing 65C02 code.



Microchess for the KIM clone

(see also the Microchess page)

Downloads:

The hex file MicroChessOut can be loaded directly into the KIM CLONE and run from $2000
Archive with source.

Following the header "Peter Jennings, www.benlo.com" I was pleasantly surprised to see the website still active:
http://benlo.com/microchess/index.html
http://benlo.com/files/Microchess6502.txt
The source code Microchess6502.txt contains the additional note on line 35:
"; Updated with corrections to earlier OCR errors by Bill Forster, August 2005."
Line 73 comments on the cross-assembler used:
"BMCC    =    $E5         ; was BCC (TASS doesn't like it as a label)"
Looking for information about TASS led me to:
https://www.c64-wiki.com/wiki/Cross_Assembler
Reading from "64Tass/6502Tass: Another native "Turbo Assembler", developed for DOS (6502Tass), later also for Unix, Linux and Windows32 (64Tass)," I suspect the 1996-2002 code by Peter Jennings used the DOS version, but I am running Windows 10 on a modern laptop and I can't find a way to run 16-bit applications without using third party tools like DosBox or an emulator in VirtualBox.
So I decided to try out Tass64.  I found a link to the Windows version on sourceforge, https://sourceforge.net/projects/tass64/.  The documentation is included in the zip file, and also here http://tass64.sourceforge.net/.
Without really reading the documents, I just ran Microchess through the Assembler and got errors.  Below are the errors I got, and how I fixed/hacked/patched each one.
First Attempt:
Error messages:    31
Warning messages:  3
Passes:            2
....Oof.....
Error Group 1:
MicroChessSource:37:8: error: general syntax
cpu 65c02
^
MicroChessSource:38:9: error: general syntax
page 0,132
^
Correction:
Change 37 to: .cpu "65c02"
Change 38 to ; page 0,132
Line 38 is commented out because 'page' "gives an error on page boundary crossing, e.g. for timing sensitive code" and I am simply going to put my faith in Peter Jennings and hope for the best here.
Line 37 can be changed to reflect the CPU you are using.  I got my parts assembled by Bob, and leaving "65c02" as the cpu version works for me on the KIM CLONE.  
Error Group 2:
MicroChessSource:729:6: error: general syntax
db      $2c             ; used to skip over LDA #$20
^
MicroChessSource:859:12: error: general syntax
Hexdigdata     asc     "0123456789ABCDEF"
Correction:
For all the lines that use "db" or "asc," change the pseudo-op to ".text"
Now I got:
-----------------------------------------------------------------------------
C> 64tass.exe -o MicroChessOut MicroChessSource
64tass Turbo Assembler Macro V1.55.2200
64TASS comes with ABSOLUTELY NO WARRANTY; This is free software, and you
are welcome to redistribute it under certain conditions; See LICENSE!
Assembling file:   MicroChessSource
Error messages:    None
Warning messages:  None
Passes:            2
Memory range:      $1000-$1524   $0525
Memory range:      $1580-$15dc   $005d
-----------------------------------------------------------------------------
I think I'd like to run Microchess from $2000 up in one block, so I will modify line 95 and 869:
Change line 95 to ";*= $1580"
and comment out line 869.
-----------------------------------------------------------------------------
Memory range:      $2000-$2581   $0582
-----------------------------------------------------------------------------
Now the source will assemble, but it won't work yet.  The Peter Jennings code with TTY was written for the "6551 Asynchronous Communications Interface Adapter (ACIA)," not the "standard TTY" routines built into the KIM monitor that we see in the First Book of KIM etc.  
http://archive.6502.org/datasheets/mos_6551_acia.pdf
https://en.wikipedia.org/wiki/MOS_Technology_6551
First, I comment out the ACIA addresses from line 42.
;ACIADat    =     $7F70
;ACIASta    =    $7F71
;ACIACmd    =    $7F72
;ACIACtl    =    $7F73
Then, I add in the addresses of the KIM monitor TTY routines for getting (blocking) and outputting 1 character.
; http://www.zimmers.net/cbmpics/cbm/kim1/kim-hints.txt - See "KIM SUBROUTINES"
TTY_GETCH = $1E5A  ; Register States: In to A, X preserved, Y = FF
TTY_OUTCH = $1EA0  ; Register States: X preserved, Y = FF, A = FF
Now, I move to line 822 and start making changes to the I/O Routines.
(1) Comment Out the Init function 825-829, don't need.  I leave the label and rts to allow it to work as a dummy sub routine rather than deleting all references to it in the code.
(2) Replace the meat of "syskin" on 833 with code to push the affected registers, call TTY_GETCH, and restore affected registers.
(3) Replace the meat of "syschout" on 842 to push the affected registers, call TTY_OUTCH, and restore affected registers.
Now the code after line 822 looks like:
;
; 6551 I/O Support Routines
; Replaced with KIM Monitor Routines for KIM Clone - Neil 2020
;
;
Init_6551      ;lda   #$1F               ; 19.2K/8/1
;sta   ACIActl            ; control reg
;lda   #$0B               ; N parity/echo off/rx int off/ dtr active low
;sta   ACIAcmd            ; command reg
rts                      ; done
;
; input chr from ACIA1 (waiting)
;
syskin         ;lda   ACIASta            ; Serial port status             
;and   #$08               ; is recvr full
;beq   syskin             ; no char to get
;Lda   ACIAdat            ; get
PHY
JSR TTY_GETCH
PLY      
RTS                    ;
;
; output to OutPut Port
;
syschout       ;PHA                      ; save registers
ACIA_Out1      ;lda   ACIASta            ; serial port status
;and   #$10               ; is tx buffer empty
;beq   ACIA_Out1          ; no
;PLA                      ; get chr
;sta   ACIAdat            ; put character to Port
PHA
PHY
JSR TTY_OUTCH
PLY
PLA
RTS                      ; done
IMPORTANT: I make use of the 6502 commands to push X and push Y, pop X, pop Y - PHX, PHY, PLY, PLX which work on the 65c02 but not the old-school 6502.  This probably won't be an issue for the KIM Clone, but if it is, it will be necessary to change the way you push and pop using your favorite method from back in the day, of one of the examples here:
http://6502.org/tutorials/register_preservation.html
Now I re-assemble the source code, adding the flag to output INTEL HEX format.  This is because Bob added support for intel hex to the [L] command on the KIM-1.  There are programs on-line (somewhere) for converting and dealing with the KIM paper tape format, but being allowed to Load in INTEL HEX format allows us to output something the KIM CLONE can read without no trouble at all.
-----------------------------------------------------------------------------
C> 64tass.exe --intel-hex -o MicroChessOut MicroChessSource
64tass Turbo Assembler Macro V1.55.2200
64TASS comes with ABSOLUTELY NO WARRANTY; This is free software, and you
are welcome to redistribute it under certain conditions; See LICENSE!
Assembling file:   MicroChessSource
Error messages:    None
Warning messages:  None
Passes:            2
Memory range:      $2000-$256e   $056e
-----------------------------------------------------------------------------
Now, I could use SecureCRT or Tera Term or some other fancy terminal to send the file as ASCII when I press the [L]oad command on the KIM-1.  Today, however, I will use the humble PuTTy terminal emulator.  And simply copy the hex to my clipboard, and paste it in PuTTy after pressing the [L] command.
KIM Clone v1.0B
237A 24 0000
:00000001FF52250D45350455220643330FCC8F02020299250B25010033250736340D3434CD
KIM Clone v1.0B
0000 00 2000
2000 A9 G
MicroChess (c) 1996-2005 Peter Jennings, www.benlo.com
00 01 02 03 04 05 06 07
-------------------------
|BP|**|  |**|BP|**|  |**|00
-------------------------
|**|  |**|  |**|  |**|  |10
-------------------------
|BB|WP|  |**|  |**|  |**|20
-------------------------
|BP|  |**|  |**|  |**|  |30
-------------------------
|BP|**|  |**|  |**|  |**|40
-------------------------
|**|  |**|  |**|  |**|  |50
-------------------------
|  |**|  |**|  |**|  |**|60
-------------------------
|**|  |**|  |**|  |**|  |70
-------------------------
00 01 02 03 04 05 06 07
20 00 00
?C
MicroChess (c) 1996-2005 Peter Jennings, www.benlo.com
00 01 02 03 04 05 06 07
-------------------------
|WR|WN|WB|WK|WQ|WB|WN|WR|00
-------------------------
|WP|WP|WP|WP|WP|WP|WP|WP|10
-------------------------
|  |**|  |**|  |**|  |**|20
-------------------------
|**|  |**|  |**|  |**|  |30
-------------------------
|  |**|  |**|  |**|  |**|40
-------------------------
|**|  |**|  |**|  |**|  |50
-------------------------
|BP|BP|BP|BP|BP|BP|BP|BP|60
-------------------------
|BR|BN|BB|BK|BQ|BB|BN|BR|70
-------------------------
00 01 02 03 04 05 06 07
CC CC CC
Personal Notes:
-The extended monitor on the KIM Clone has extra for string printing and more, so if I was doing a serious "KIM CLONE" port, I might look at rewriting a lot of the drawing functions.  
-It is really clunky how the screen re-draws after every CHARACTER -- which means I have to sit through 4 board redraws just to enter a move.  I want to update that code, because I don't have pre-digital age patience.
-My cross compiler of choice is ca65, part of the cc65 C compiler for the 6502.  Maybe a ca65 port of the syntax is something I might try.
There are great usage notes for this version of the game here:
https://obsolescence.wixsite.com/obsolescence/kim-uno-microchess
Too late now, but I notice he went through the exact same process changing the UART routines for his version of MicroChess for the Arduino KIM-1 emulator.

KIM Monitor KIM clone

KIM monitor as modified for the Corsham Tech KIM Clone board.

Notable changes:
* Removal of the code to save/load from cassette tape.
* Lunar Lander (First Book of KIM) added.
* Famer Brown (First Book of KIM) added.
* New X command from TTY to enter the Corsham Technologies xKIM extended monitor.

See also the Corsham github page.

Download the KIM Monitor repository copy here.

Note that you can use the standard KIM ROMs also, the KIM Clone is a KIM-1.

Extended KIM Monitor

# xKIM

xKIM is an extended monitor for KIM computer systems. Commonly used in Corsham Technologies KIM-1 add-on boards.
It is a 6502 based monitor which has basic tools as well as some additional commands for working
with the Corsham Tech SD Card system.

## Features
* Pure 6502 code.
* Many subroutines available for external programs to use.
* Can auto-run Intel hex files upon loading.
* Can be placed in read-only memory.
* Has all low-level subroutines for talking to the SD Card.
* New commands can be added at run-time to the command handler.

## Command Summary (not a complete list)
* Examine/edit memory.
* Jump to code.
* Load Intel hex file from console or SD card.
* Directory of SD card.
* Get clock from RTC.
* Memory test.
* Branch offset calculator, also within memory editor.
* Type SD file.
* Save memory to SD file.

Downloads:
xKIM-master 2021
xKIM older versions

xKIM Manual 1.6

Parallel port adapter

A small project to convert the connector on the KIM I/O board to a Parallel Port adapter (2021).


KIM-1 Software

Bob Applegate published quite a lot of 6502 code.