Split from cpm repository

src/loader.z80

@@ -0,0 +1,30 @@
+;Retrieves CP/M from disk and loads it in memory starting at E400h
+;Uses calls to ROM subroutine for disk read.
+;Reads track 0, sectors 2 to 26, then track 1, sectors 1 to 25
+;This program is loaded into LBA sector 0 of disk, read to loc. 0800h by ROM disk_read subroutine, and executed.
+
+#target bin
+#code _HOME, 0x1100
+
+hstbuf    equ 0x1200         ;will put 256-byte raw sector here
+disk_read equ 0x0296         ;subroutine in 2K ROM
+cpm       equ 0xFA00         ;CP/M cold start entry in BIOS
+
+main:
+	ld c,1                   ;LBA bits 0 to 7
+	ld b,0                   ;LBA bits 8 to 15
+	ld e,0                   ;LBA bits 16 to 23
+	ld hl,0xE400             ; Memory address -- start of CCP
+
+loop:
+	call disk_read           ;subroutine in ROM
+	ld a,c
+	cp 50
+	jp z,done
+	inc a
+	ld c,a
+	jp loop
+
+done:
+	out (1),a                ;switch memory config to all-RAM
+	jp cpm                   ;to BIOS cold start entry