socz80: boot to a shell prompt, achievement unlocked

The tty code still needs prodding and debugging to get the interrupt handling
fixed. It would also be better to use custom usermem functions that used the
MMU page 17, but the old uzi180 style ones need modifying somewhat to handle
bank boundaries.

No swap (seriously you've got 2MB RAM), sd card as "floppy" device.

diff --git a/Kernel/platform-socz80/README b/Kernel/platform-socz80/README
index 2ee3107..e24da52 100644 (file)
--- a/Kernel/platform-socz80/README
+++ b/Kernel/platform-socz80/README
@@ -5,7 +5,7 @@ At this point in time it supports the following components
 - timer
 - ramdiscs
 - SD card
-- two serial ports (USB virtual and native)
+- two serial ports (USB virtual and native) (currently not quite working)
 
 It does not support
 - speed setting on the uarts with the newer FPGA firmware
@@ -21,3 +21,13 @@ array in HL.
 This port is heavily based upon (and mostly consists of) code by Will
 Sowerbutts.
 
+
+
+MMU
+---
+
+The MMU has 4K pages, but we use them in 16K blocks. It also supports both
+read-only pages and an MMU bypass for copying memory. The read-only bit
+isn't yet used but ought to be used to protect kernel space. The bypass mode
+is used and any code using it *MUST* not use it from an IRQ or if it does
+must save/restore it properly.

diff --git a/Kernel/platform-socz80/config.h b/Kernel/platform-socz80/config.h
index e7cac40..c80e571 100644 (file)
--- a/Kernel/platform-socz80/config.h
+++ b/Kernel/platform-socz80/config.h
@@ -18,7 +18,7 @@
 #define TICKSPERSEC 100                /* Ticks per second */
 #define PROGBASE    0x0000
 #define PROGLOAD    0x0100     /* also data base */
-#define PROGTOP     0xF700     /* Top of program, base of U_DATA */
+#define PROGTOP     0xF800     /* Top of program, base of U_DATA */
 
 #define BOOT_TTY (512 + 1)/* Set this to default device for stdio, stderr */
                           /* In this case, the default is the first TTY device */

diff --git a/Kernel/platform-socz80/fuzix.lnk b/Kernel/platform-socz80/fuzix.lnk
index 50fa2df..2244a9d 100644 (file)
--- a/Kernel/platform-socz80/fuzix.lnk
+++ b/Kernel/platform-socz80/fuzix.lnk
@@ -1,7 +1,7 @@
 -mwxuy
 -i fuzix.ihx
 -b _CODE=0x0088
--b _COMMONMEM=0xF700
+-b _COMMONMEM=0xF800
 -b _DISCARD=0xE000
 -l z80
 platform-socz80/crt0.rel

diff --git a/Kernel/platform-socz80/kernel.def b/Kernel/platform-socz80/kernel.def
index e4860e3..bf28fa4 100644 (file)
--- a/Kernel/platform-socz80/kernel.def
+++ b/Kernel/platform-socz80/kernel.def
@@ -1,6 +1,6 @@
 ; UZI mnemonics for memory addresses etc
 
-U_DATA                      .equ 0xf700       ; (this is struct u_data from kernel.h)
+U_DATA                      .equ 0xf800       ; (this is struct u_data from kernel.h)
 U_DATA__TOTALSIZE           .equ 0x300        ; 256+256+256 bytes.
 
 Z80_TYPE                   .equ 0            ; Actually a T80

diff --git a/Kernel/platform-socz80/tricks.s b/Kernel/platform-socz80/tricks.s
index 7fc5e4b..b7717e2 100644 (file)
--- a/Kernel/platform-socz80/tricks.s
+++ b/Kernel/platform-socz80/tricks.s
@@ -1,4 +1,5 @@
 ; 2013-12-21 William R Sowerbutts
+; 2015-01-30 Alan Cox
 
         .module tricks
 
@@ -24,7 +25,14 @@
         .include "../kernel.def"
         .include "kernel.def"
 
-        .area _COMMONMEM
+;
+;      These do not need to be in common memory as we don't have to
+;      pull udata remapping tricks on a 16K banked system. In the case of
+;      SocZ80 they *MUST NOT* be in common as they reload the MMU page for
+;      0xF000. That takes multiple instructions and the code will vanish
+;      midstream if it is in common space!
+;
+       .area _CODE2
 
 ; Switchout switches out the current process, finds another that is READY,
 ; possibly the same process, and switches it in.  When a process is
@@ -193,11 +201,14 @@ _dofork:
         ; load into MMU
         ld a, #0x0F
         out (MMU_SELECT), a
-        ld a, d
+        ld a, h
         out (MMU_FRAMEHI), a
-        ld a, e
+        ld a, l
         out (MMU_FRAMELO), a
 
+       ld a,#'!'
+       call outchar
+
         ; now the copy operation is complete we can get rid of the stuff
         ; _switchin will be expecting from our copy of the stack.
         pop bc
@@ -267,9 +278,6 @@ bank_copy:
 
        ; save the parent mapping
        ld b, a
-       call outcharhex
-       ld a, c
-       call outcharhex
         ; store the old MMU mapping
         ld a, #0x0E
         out (MMU_SELECT), a
@@ -290,8 +298,8 @@ bank_copy:
 
         ; child base page is in c parent in b
        ld d,#0
-       ld l,d
-       ld c,a
+       ld l, d
+       ld a, c
        sla a
        rl d
        sla a
@@ -308,6 +316,7 @@ bank_copy:
        rl d
        sla a
        rl d           ; de now holds the src pointer
+       ld e, a
 
         ld b, #4 ; we're going to copy 16K
 copynextpage:
@@ -329,6 +338,8 @@ copynextpage:
         push hl
         push de
         push bc
+       call outde
+       call outhl
 
         ld hl, #0xe000
         ld de, #0xd000