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Do (hopefully) MMU and serial setup

This commit is contained in:
mgcaret 2019-11-30 21:09:35 -08:00
parent a641a6b3a1
commit 91af87fa4e
1 changed files with 45 additions and 7 deletions
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52
platforms/Neon816/Neon816.s
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@ -6,27 +6,65 @@
.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
lda #$0300 ; direct page for Forth
.a16
.i16
; MMU setup, maybe. Found at page $FF in Neon bank 0
ldx #$001C
lda #$8000
: sta f:$080000,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:$10000A
lda #$06
sta f:$10000B
lda #$00
sta f:$10000C
rep #SHORT_A|SHORT_I
.a16
.i16
lda #$0000 ; direct page for Forth
tcd
lda #.hiword($020000) ; top of dictionary memory
lda #.hiword($0A0000) ; top of dictionary memory
pha
lda #.loword($020000)
lda #.loword($0A0000)
pha
lda #.hiword($010000) ; bottom of dictionary
lda #.hiword($090000) ; bottom of dictionary
pha
lda #.loword($010000)
lda #.loword($090000)
pha
lda #$0300 ; first usable stack cell (relative to direct page)
lda #$0200 ; first usable stack cell (relative to direct page)
pha
lda #$0100 ; last usable stack cell+1 (relative to direct page)
pha
lda #$09FF ; return stack first usable byte
lda #$03FF ; return stack first usable byte
pha
lda #.hiword(_system_interface)
pha