Working on the Neon816

.gitignore

@@ -10,4 +10,6 @@ t
 *.po
 romfs
 .DS_Store
+*.hex
+of816-neon.bin
 

platforms/Neon816/Neon816-hw.inc

@@ -1,6 +1,31 @@
 
+; Bank Map from FB posting by Lenore:
+; 00 Bank Mapper (16 blocks of 4k each, configured via MMU)
+; 08-0F Bus Controller Peripherals
+; - 08 0000-003F MMU
+; -- 00: 0-3 Unused, 4-7: Upper RAM bits
+; -- 01: Bank
+; - 09 FDC
+; 10-1F Internal Bus Bridge
+; 20-27 Flash ROM
+; 28-3F Reserved for Flash
+; 30-3F Reserved for Expansion Flash
+; 40-47 Video RAM
+; 48-7F Reserved for VRAM
+; 80-87 RAM 1
+; 88-8F RAM 2
+; 90-FF Reserved for RAM
+
 cpu_clk   = 14000000
 
+; *****************
+; Memory regions
+; *****************
+Neon_ROM  = $200000
+Neon_VRAM = $400000
+Neon_RAM1 = $800000
+Neon_RAM2 = $880000
+
 ; *****************
 ; MMU
 ; *****************

platforms/Neon816/Neon816.l

@@ -1,16 +1,18 @@
 FEATURES {
-	STARTADDRESS: default = $0000;
+	STARTADDRESS: default = $200000;
 }
 
 MEMORY {
-	ROM: start = $0000, size = $10000, file = %O;
+	ROM: start = $200000, size = $10000, fillval=$FF, file = %O;
 	ZP: start = $0000, size = $100;
 }
 
 SEGMENTS {
-	FStartup: load=ROM,type=ro;
+	FStartup: load=ROM, type=ro, fillval=$00;
-	FSystem: load=ROM, type=ro;
+	FSystem: load=ROM, type=ro, fillval=$00;
-	FCode: load=ROM, type=ro, optional=yes;
+	FCode: load=ROM, type=ro, fillval=$00, optional=yes;
+	ROMBOOT: load=ROM, type=ro, offset=$FF00;
+	VECTORS: load=ROM, type=ro, offset=$FFE0;
 	ZEROPAGE: load=ZP, type=bss;
 }
 

platforms/Neon816/Neon816.s

@@ -7,65 +7,31 @@
 .import   _Forth_ui
 .import   _system_interface
 
-; Bank Map from FB posting by Lenore:
-; 00 Bank Mapper (16 blocks of 4k each, configured via MMU)
-; 08-0F Bus Controller Peripherals
-; - 08 0000-003F MMU
-; -- 00: 0-3 Unused, 4-7: Upper RAM bits
-; -- 01: Bank
-; - 09 FDC
-; 10-1F Internal Bus Bridge
-; 20-27 Flash ROM
-; 28-3F Reserved for Flash
-; 30-3F Reserved for Expansion Flash
-; 40-47 Video RAM
-; 48-7F Reserved for VRAM
-; 80-87 RAM 1
-; 88-8F RAM 2
-; 90-FF Reserved for RAM
-
 .pushseg
 .segment  "FStartup"
 .proc     startup
           clc
           xce
-          rep   #SHORT_A|SHORT_I
+          phk
-          .a16
+          plb
-          .i16
-          ; MMU setup, maybe.  Found at page $FF in Neon bank 0
-          ldx   #$001C
-          lda   #$8000
-:         sta   f:NeonMMU,x
-          dex
-          dex
-          bpl   :-
-          ; NeonFORTH does this, presumably to initialize the serial port
-          sep   #SHORT_A          ; not necessary unless we were already native & long
-          .a8
-          lda   #$8D
-          sta   f:SERctrlA
-          lda   #$06
-          sta   f:SERctrlB
-          lda   #$00
-          sta   f:SERctrlC
           rep   #SHORT_A|SHORT_I
           .a16
           .i16
           lda   #$0000            ; direct page for Forth
           tcd
-          lda   #.hiword($0A0000)   ; top of dictionary memory
+          lda   #.hiword(Neon_RAM1+$020000) ; top of dictionary memory
           pha
-          lda   #.loword($0A0000)
+          lda   #.loword(Neon_RAM1+$020000)
           pha
-          lda   #.hiword($090000)   ; bottom of dictionary
+          lda   #.hiword(Neon_RAM1+$010000) ; bottom of dictionary
           pha
-          lda   #.loword($090000)
+          lda   #.loword(Neon_RAM1+$010000)
           pha
-          lda   #$0200            ; first usable stack cell (relative to direct page)
+          lda   #$0400            ; first usable stack cell (relative to direct page)
           pha
-          lda   #$0100            ; last usable stack cell+1 (relative to direct page)
+          lda   #$0204            ; last usable stack cell+1 (relative to direct page)
           pha
-          lda   #$03FF            ; return stack first usable byte
+          lda   #$01EF            ; return stack first usable byte
           pha
           lda   #.hiword(_system_interface)
           pha
@@ -73,7 +39,6 @@
           pha
           jsl   _Forth_initialize
           jsl   _Forth_ui
-          brk
+          jmp   startup
-          .byte $00
 .endproc
 .popseg

platforms/Neon816/README.md

@@ -1,21 +1,66 @@
+
 # Neon816
 
-This is a port to Lenore Byron's [Neon816](https://hackaday.io/project/164325-neon816)
+This is a port to Lenore Byron's [Neon816](https://hackaday.io/project/164325-neon816) system.  The Neon816 Developer Edition ships with a small 16-bit Forth.
-system.  The Neon816 Developer Edition ships with a small 16-bit Forth.
 
-At the time of commit 91af87fa4e42dced1d22d3cb620e84e6edb91817, OF816 for the Neon816
+OF816 for the Neon816 is configured to run as an alternative firmware out of bank $20.  With a little ajustment, it could be configured to run out of bank $21 (but starting it is an excercise for the reader).
-is configured to run out of any available ROM bank at starting address $0000.  It configures
+
-the MMU hopefully like NeonFORTH does, sets the data stack from $0000-$01FF and the return stack from $0200-$03FF.  It hopefully also configures the serial port.
+It configures the MMU and serial port like NeonFORTH does.  The direct page, stack, and return stack occupy the first $400 bytes of RAM.
 
 To build OF816 for the Neon816, change to the platform directory and run
-build.sh. It will output a binary named "forth" that can be started at address $0000 of the
+``build.sh``. It will output a 64K binary named ``of816-neon.bin`` that can be flashed into the Neon's firmware.  See below for installation instructions.
-bank it is loaded into. 
-
-At this point nothing further can be done until we have the ability to use the debug port to
-load OF816 into the flash ROM.
 
 ## Port Features
 
 Hopefully this section will be filled up with stuff that works like Lenore's
-Forth.  See the [Neon816 Manual](https://cdn.hackaday.io/files/1643257030480800/sysmanual.pdf)
+Forth.  See the [Neon816 Manual](https://cdn.hackaday.io/files/1643257030480800/sysmanual.pdf).  But right now, it's just a bare port with no system-specific extensions.
 
+## Installation
+
+**THIS WILL OVERWRITE THE NEON'S ORIGINAL FIRMWARE.**
+
+**IT IS STRONGLY RECOMMENDED YOU BACK UP THE ORIGINAL FIRMWARE**
+
+**READ _ALL_ OF THE FOLLOWING BEFORE PROCEEDING AND DO NOT PROCEED IF ANY OF THIS MAKES YOU UNCOMFORTABLE**
+
+After building the firmware image, the image must be converted to Intel Hex format.  I like the bin2hex tool found [here](https://grumpf.hope-2000.org) (page is in German). Build the ``bin2hex`` binary and execute:  ``bin2hex of816-neon.bin > of816-neon.hex`` 
+
+Once you have the .hex file, you will need to use the [Neon firmware loader](https://hackaday.io/project/164325-neon816) to install the image.  This requires an FTDI cable connected to the 3.3V UART header on the Neon816 system board.
+
+To back up the original firmware, you will need to add an additional command routine to neonprog.cpp (add it after the write command):
+
+```
+   else if(!strcmp(cmd,"dumprom")) {
+        char* fn=strtok(nullptr," ");
+        char buf[0x40];
+        if(!fn) return;
+        auto st=Releaser(
+            fopen(fn,"w"),
+            [](auto f){if(f) fclose(f);});
+        if(!st) {
+            printf("Could not open file\n");
+            return;
+        }
+        for (int addr=0x200000; addr<0x220000; addr+=sizeof(buf)) {
+            writeHex(addr>>16,2); writeChar(':');
+            writeHex(addr,4); writeChar('#');
+            for (int i=0; i<sizeof(buf); i++) {
+                writeChar('@');
+                unsigned char c=readByte();
+                buf[i]=c;
+            }
+            fwrite(&buf, sizeof(buf), 1, st);
+            printf("%08X\n",addr);
+        }
+    }
+```
+
+then start neonprog with ``neonprog /dev/ttyUSBx`` (replace device with actual serial device for FTDI cable.
+
+From within neonprog, execute ``dumprom backup.bin`` to save an image of both ROM banks to ``backup.bin``.
+
+Once the backup has finished (it will take a while), you can proceed to the installation of OF816 with ``flash of816-neon.hex``.  This will also take a while.  When it is done, reset your Neon and OF816 should start.
+
+## Restoring the Original NeonFORTH Firmware
+
+Since the Neon (at the time of this writing) only ships with the first bank of flash occupied, first, split your backup with ``split backup.bin``.  This will output two files, ``xaa`` and ``xab`` that are bank $20 and bank $21, respectively.  Then run ``hex2bin xaa > neonforth.hex``.  You can then flash this with neonprog using ``flash neonforth.hex``.   Once it's done, reset your Neon and you should see the original firmware running.

platforms/Neon816/build.sh

@@ -1,7 +1,12 @@
 #!/bin/bash
 set -e -x
 ca65 -I ../../inc Neon816.s -l Neon816.lst
+ca65 -I ../../inc romboot.s -l romboot.lst
 ../../build.sh Neon816
-ld65 -C Neon816.l -S 0x8000 Neon816.o ../../forth.o -m forth.map -o forth
+ld65 -C Neon816.l -S 0x8000 Neon816.o ../../forth.o ./romboot.o -m forth.map -o of816-neon.bin
-ls -l forth
+ls -l of816-neon.bin
+if which -s bin2hex; then
+  hex2bin of816-neon.bin > of816-neon.hex
+  ls -l of816-neon.hex
+fi
 

platforms/Neon816/platform-lib.s

@@ -7,7 +7,7 @@
           phx
           asl
           tax
-          jmp   (table,x)
+          jmp   (.loword(table),x)
 table:    .addr _sf_pre_init
           .addr _sf_post_init
           .addr _sf_emit
@@ -34,8 +34,19 @@ table:    .addr _sf_pre_init
 
 
 .proc     _sf_pre_init
+          ; NeonFORTH does this, presumably to initialize the serial port
+          sep   #SHORT_A
+          .a8
+          lda   #$8D
+          sta   f:SERctrlA
+          lda   #$06
+          sta   f:SERctrlB
+          lda   #$00
+          sta   f:SERctrlC
+          rep   #SHORT_A
+          .a16
           plx
-          jmp   _sf_success     ; we'll see what we need to do
+          jmp   _sf_success
 .endproc
 
 .proc     _sf_post_init

platforms/Neon816/romboot.s

@@ -0,0 +1,46 @@
+.p816
+.a16
+.i16
+.include  "macros.inc"
+.include  "./Neon816-hw.inc"
+
+.segment  "ROMBOOT"
+.proc     romboot
+          clc
+          xce
+          rep   #SHORT_A|SHORT_I
+          .a16
+          .i16
+          lda   #$01FF
+          tcs
+          ; Set up MMU for bank 0
+          ldx   #$001C
+          lda   #$8000
+:         sta   f:NeonMMU,x
+          dex
+          dex
+          bpl   :-
+          jml   f:Neon_ROM
+.endproc
+
+.segment  "VECTORS"
+.proc     vectors
+          ; native mode vectors
+          .word $FFFF             ; FFE0 - reserved
+          .word $FFFF             ; FFE2 - reserved
+          .word $FFFF             ; FFE4 - COP
+          .word $FFFF             ; FFE6 - BRK
+          .word $FFFF             ; FFE8 - ABORT
+          .word $FFFF             ; FFEA - NMI
+          .word $FFFF             ; FFEC - reserved
+          .word $FFFF             ; FFEE - IRQ
+          ; emulation mode vectors
+          .word $FFFF             ; FFF0 - reserved
+          .word $FFFF             ; FFF2 - reserved
+          .word $FFFF             ; FFF4 - COP
+          .word $FFFF             ; FFF6 - reserved
+          .word $FFFF             ; FFF8 - ABORT
+          .word $FFFF             ; FFFA - NMI
+          .word .loword(romboot)  ; FFFC - RESET
+          .word $FFFF             ; FFFE - IRQ/BRK
+.endproc