6809 code try and add multicomp UART
====================================

I wanted to learn about the 6809 and get a program to load HEX code
and run it in a command line program so test new HEX files.

The 6809 interfaces to a 68B50 ACAI or UART chip.

Run MultiComp for 6809 

 * VirtualMultiComp for 6809
 * 
 * emulate a 6809 minimal component board.
 * 
 * See:http://www.searle.wales/ Grant's 6-chip 6809 computer
 * 
 * This has a 6809 CPU, RAM, ROM, UART and wiring.
 * 
 * This program has 
 * 	CPU, based on:- Arto Salmi's 6809.
 * 	RAM, memory
 * 	ROM, using routines to upload HEX file before CPU reset.
 *  UART, routines to use STDIN and STDOUT and look like a UART to CPU.	
 *  wiring - decodes RAM and IO addresses in WRMEM() and RDMEM()
 *
 * based on:- Arto Salmi's 6809.
 * http://atjs.mbnet.fi/mc6809/		
 * http://atjs.mbnet.fi/mc6809/6809Emulators/6809.zip
 *
 * Albert van der Horst - AS9 assembler
 * http://home.hccnet.nl/a.w.m.van.der.horst/m6809.html
 
 * http://www.searle.wales/ Grant's 6-chip 6809 computer
 * In SBC  version UART @ 0xA000 and 0xA001 and uses STDIN and STDOUT
 * In FPGA version UART @ 0xFFD0 and 0xFFD1 and uses STDIN and STDOUT
 * 
 * The UART uses a thread as getchar() blocks.
 * 
 * usage: 
 * gcc virtual.c 6809v.c -pthread -o virtual
 * gcc -o virtual virtual.c 6809v.c -pthread 
 *
 * ./virtual doug.s19
 * 
 * stty sane
 * 
 *usage: - loading Grant's modified BASIC for 6809 ( UART @ 0xA000)
 * ./virtual ExBasROM.hex -hex
 * stty sane
 * 
 * NOTE: Download ExBasROM.hex for 6809 6 chip SBC, not FPGA version.
 * 
 * backspace or delete do not seem to work yet! UPPER CASE needed.
 * 
 * To upload BASIC code, paste the code into the terminal session.
 * 
 * CheckKey() waits until UART RX buffer is read.
 * 
 * However if you use pipes, pressing the keyboard does not work.
 *
 * cat buff.txt | ./virtual ExBasROM.hex -hex 
 * or
 *  ./virtual ExBasROM.hex -hex < buff.txt
 * 
 * as pressing the keyboard does not seem work.
 *  
 * 
pi@raspberrypiwww:~/Desktop/m68/6809_multicomp $ ./virtual ExBasROM.hex -hex
Loading code...
AS,JF, 1.2, file ExBasROM.hex     press q to quit 
6809 EXTENDED BASIC
(C) 1982 BY MICROSOFT

OK

  * 
  * LIST
  * 
10 X=0
20 PRINT "hELLO"
30 PRINT "HEOOL"
40 PRINT "Hello world"
50 X=X+1
60 IF X < 100 THEN GOTO 20
 
RUN 

OK
* 
* 
*  
10 A$=CHR$(27)
15 PRINT A$
20 PRINT "[103m"
30 PRINT "HELLO"
* 
*/


6809 sees UART at 0xFFD0 & 0xFFD1 as used in FPGA
6809 sees UART at 0xA000 & 0xA001 as used in SBC

virtual.c emulated enough of UART and used STDIN and STDOUT

build:-
gcc virtual.c 6809v.c -pthread -o virtual

run 6809 code - use q to end. 
./virtual doug.s19
stty sane

Use SBC ExBasicROM.HEX 
The hex file  FPGA has addesses 0000 to 1FFF and used at E000 to FFFF 

It does not run basic as ROMS are not locaated from 0x0000
FPGA UART is at $FFD0 & $FFD1
Grant's 6-chip 6809 computer has UART is at A000-BFFF SERIAL INTERFACE (minimally decoded)

Memory Map

0000-7FFF 32K RAM
8000-9FFF FREE SPACE (8K)
A000-BFFF SERIAL INTERFACE (minimally decoded)
C000-FFFF 16K ROM (BASIC from DB00 TO FFFF, so a large amount of free space suitable for a monitor etc)

Grant has a comment about compiling the BASIC program.
as9 exbasrom.asm -now l s19
./as9 ExBasRom.asm -now l s19 hex


./virtual ExBasRom.s19 

"-now" suppresses warnings
"l" produces a lst file
"s19" produces an s19 hex file


/*
 * VirtualMultiComp for 6809 
 * UART at 0xFFD1/0 and uses STDIN and STDOUT
 * 
 * Links
 * 
 * The following links were very useful to me...
 * 
 * Albert van der Horst - AS9 assembler
 * http://home.hccnet.nl/a.w.m.van.der.horst/m6809.html
 * 
 * Arto Salmi - 6809 Emulation and links page
 * http://koti.mbnet.fi/~atjs/mc6809/
 *
 * based on:- Arto Salmi's 6809.
 * http://atjs.mbnet.fi/mc6809/		
 * http://atjs.mbnet.fi/mc6809/6809Emulators/6809.zip
 * 
 * 
 * http://www.searle.wales/			multicomp for 6809.
 * UART at 0xFFD1/0 and 0xA000/1 It uses STDIN and STDOUT
 * 
 * usage: 
 * gcc virtual.c 6809v.c -pthread -o virtual
 * gcc -o virtual virtual.c 6809v.c -pthread 
 *
 * ./virtual doug.s19
 * 
 * stty sane
 * 
 *usage: - loading Grant's modified BASIC for 6809 SBC ( UART @ 0xA000)
 * ./virtual ExBasROM.hex -hex
 * stty sane
 * 
 * NOTE: Use ExBasROM from 6809 SBC, not FPGA version.
 * 
 * backspace or delete do not seem to work yet!
 * It could do with a way to pipe a file to upload code.
 *