Relocated monitor to top 16k
This commit is contained in:
Joppe Blondel
@@ -9,10 +9,13 @@ METAL_RELFILES := $(METAL_ASM_SRCFILES:%.asm=$(BUILDDIR)/metal/%.rel) \
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METAL_CC := sdcc
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METAL_AS := sdasz80
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METAL_MAKEBIN := makebin
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METAL_FLAGS := -mz80 --no-std-crt0 --code-loc 0x0080 --data-loc 0x8000
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METAL_FLAGS := -mz80 --no-std-crt0 --code-loc 0xC080 --code-size 0x2F80 --data-loc 0xF000
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METAL_CPPFLAGS := -I src -I $(BUILDDIR)/metal/generated --disable-warning 283
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METAL_BIN_SIZE := 32768
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METAL_RAM_SIZE := 32768
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METAL_RAM_SIZE := 16384
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METAL_IMAGE_SIZE := 65536
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MONITOR_BASE := 0xC000
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MONITOR_ROM_OFFSET := 128
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.DEFAULT_GOAL := metal
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@@ -21,24 +24,34 @@ METAL_RAM_SIZE := 32768
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all: metal
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metal: $(BUILDDIR)/metal/$(TARGET).ihx $(BUILDDIR)/metal/$(TARGET).bin $(BUILDDIR)/metal/$(TARGET).prog.bin
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@awk -v rom_capacity=$(METAL_BIN_SIZE) -v ram_capacity=$(METAL_RAM_SIZE) '\
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$$1 ~ /^_(CODE|HOME|GSINIT|GSFINAL|INITIALIZER|ITABLE[0-7]*)$$/ { rom += $$5 } \
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$$1 ~ /^_(DATA|INITIALIZED|BSEG|BSS|HEAP|STACK)$$/ { ram += $$5 } \
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@stored=$$(wc -c < $(BUILDDIR)/metal/$(TARGET).prog.bin); \
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awk -v rom_capacity=$(METAL_BIN_SIZE) -v stored=$$stored -v ram_capacity=$(METAL_RAM_SIZE) '\
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$$1 ~ /^_(CODE|HOME|GSINIT|GSFINAL|INITIALIZER)$$/ || $$1 ~ /^_ITABLE/ { code += $$5 } \
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$$1 ~ /^_(DATA|INITIALIZED|BSEG|BSS|HEAP)$$/ { data += $$5 } \
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END { \
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printf "\nMemory usage:\n"; \
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printf " ROM: %5u / %5u bytes (%5.1f%%), %5u bytes free\n", rom, rom_capacity, 100 * rom / rom_capacity, rom_capacity - rom; \
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printf " RAM: %5u / %5u bytes (%5.1f%%), %5u bytes free\n", ram, ram_capacity, 100 * ram / ram_capacity, ram_capacity - ram; \
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printf " ROM storage: %5u / %5u bytes (%5.1f%%)\n", stored, rom_capacity, 100 * stored / rom_capacity; \
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printf " Runtime RAM: %5u / %5u bytes (%5.1f%%), %5u bytes for growth/stack\n", code + data, ram_capacity, 100 * (code + data) / ram_capacity, ram_capacity - code - data; \
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printf " code/vector: %5u bytes; static data: %5u bytes\n", code, data; \
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}' $(BUILDDIR)/metal/$(TARGET).map
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$(BUILDDIR)/metal/$(TARGET).ihx: $(METAL_RELFILES)
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@mkdir -p $(@D)
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$(METAL_CC) $(METAL_FLAGS) -o $@ $(METAL_RELFILES)
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$(BUILDDIR)/metal/$(TARGET).bin: $(BUILDDIR)/metal/$(TARGET).ihx
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$(METAL_MAKEBIN) -s $(METAL_BIN_SIZE) $< $@
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$(BUILDDIR)/metal/$(TARGET).flat.bin: $(BUILDDIR)/metal/$(TARGET).ihx
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$(METAL_MAKEBIN) -s $(METAL_IMAGE_SIZE) $< $@
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$(BUILDDIR)/metal/$(TARGET).prog.bin: $(BUILDDIR)/metal/$(TARGET).ihx
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$(METAL_MAKEBIN) -p $< $@
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$(BUILDDIR)/metal/$(TARGET).prog.bin: $(BUILDDIR)/metal/$(TARGET).flat.bin
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@payload_end=$$(awk '$$1 == "DEF" && $$2 == "monitor_image_end" { print $$3 }' $(BUILDDIR)/metal/$(TARGET).noi); \
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payload_size=$$((payload_end - $(MONITOR_BASE))); \
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test $$payload_size -gt 0; \
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dd if=$< of=$@ bs=1 count=$(MONITOR_ROM_OFFSET) status=none; \
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dd if=$< of=$@ bs=1 skip=$$(( $(MONITOR_BASE) )) seek=$(MONITOR_ROM_OFFSET) count=$$payload_size conv=notrunc status=none
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$(BUILDDIR)/metal/$(TARGET).bin: $(BUILDDIR)/metal/$(TARGET).flat.bin $(BUILDDIR)/metal/$(TARGET).prog.bin
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dd if=$< of=$@ bs=$(METAL_BIN_SIZE) count=1 status=none
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dd if=$(BUILDDIR)/metal/$(TARGET).prog.bin of=$@ conv=notrunc status=none
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$(BUILDDIR)/metal/%.rel: %.c
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@mkdir -p $(@D)
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@@ -1,7 +1,14 @@
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# Z80 UART monitor
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This ROM provides a small interactive monitor on the UART/CTC card at I/O base
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`20`. Connect a terminal at **2400 baud, 8 data bits, no parity, 1 stop bit**.
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`20`. At reset, a small ROM bootstrap copies the monitor into the top 16 KiB of
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RAM at `C000-FFFF` and starts it there. Only the occupied vector/code bytes are
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stored and copied; uninitialized data is cleared directly in high RAM. The low ROM can subsequently be disabled
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without taking the monitor, its data, or its interrupt table away. Runtime code
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and vectors occupy the lower part of this window, globals begin at `F000`, and
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the stack grows downward from `FFFF`; no RAM below `C000` is used.
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Connect a terminal at **2400 baud, 8 data bits, no parity, 1 stop bit**.
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Commands are case-insensitive and all numeric arguments are hexadecimal; an
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optional `0x` prefix is accepted.
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@@ -26,4 +33,12 @@ make
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```
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The outputs are `build/metal/monitor.bin` (32 KiB ROM image) and
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`build/metal/monitor.prog.bin` (compact programmer image).
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`build/metal/monitor.prog.bin` (compact programmer image). The ROM layout is:
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- `0000-007F`: reset/copy bootstrap
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- `0080...`: compact vector/code image copied to RAM starting at `C000`
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- Remaining bytes: unused and available for additional ROM content
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The monitor executable starts at `C080`; its IM 2 vector table is at `C040`.
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`monitor.prog.bin` ends immediately after the occupied payload, while
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`monitor.bin` remains a complete 32 KiB chip image.
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@@ -1,5 +1,7 @@
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STACK_TOP = 0xFFFF
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DELAY_LOOPS_PER_MS = 40
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MONITOR_BASE = 0xC000
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MONITOR_ROM_SOURCE = 0x0080
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.globl _main
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.globl _delay_ms
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@@ -8,33 +10,49 @@ DELAY_LOOPS_PER_MS = 40
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.globl _enable_interrupts
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.globl _disable_interrupts
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.globl _jump_to
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.globl monitor_image_end
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.globl s__DATA
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.globl l__DATA
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.globl s__INITIALIZER
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.globl s__INITIALIZED
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.globl l__INITIALIZER
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.area _ITABLE (ABS)
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.area _BOOT (ABS)
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.org 0x00
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jp init
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jp boot_copy
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.org 0x08
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boot_copy:
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di
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ld sp, #STACK_TOP
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ld hl, #MONITOR_ROM_SOURCE
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ld de, #MONITOR_BASE
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ld bc, #(monitor_image_end - MONITOR_BASE)
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ldir
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jp init
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.area _ITABLE (ABS)
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; The executable vector page is part of the image copied to high RAM.
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.org MONITOR_BASE
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jp init
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.org MONITOR_BASE + 0x08
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reti
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.org 0x10
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.org MONITOR_BASE + 0x10
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reti
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.org 0x18
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.org MONITOR_BASE + 0x18
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reti
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.org 0x20
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.org MONITOR_BASE + 0x20
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reti
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.org 0x28
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.org MONITOR_BASE + 0x28
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reti
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.org 0x30
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.org MONITOR_BASE + 0x30
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reti
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.org 0x38
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.org MONITOR_BASE + 0x38
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reti
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; ITABLE
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.org 0x40
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; IM 2 table: the CTC supplies vectors 40, 42, 44, and 46.
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.org MONITOR_BASE + 0x40
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.dw ctc_isr ; CTC channel 0: vector 0x40
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.dw ctc_isr ; CTC channel 1: vector 0x42
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.dw ctc_isr ; CTC channel 2: vector 0x44
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@@ -48,7 +66,7 @@ init:
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call gsinit
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; Setup interrupt mode 2
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xor a
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ld a, #0xC0
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ld i, a
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im 2
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call _main
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@@ -88,6 +106,7 @@ clear_loop:
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gsinit_done:
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.area _GSFINAL
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ret
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monitor_image_end:
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.area _CODE
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