From 4b850601398c0ffd535b47297381cfb8a33320e2 Mon Sep 17 00:00:00 2001
From: Lauren Toivanen <jt@jakest.us>
Date: Mon, 28 Jul 2025 06:50:19 +0300
Subject: [PATCH] stuff and things

---
 .gitignore |  4 +++
 README.md  | 52 +++++++++++++++++++++++++++++++
 boot.asm   | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 146 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 README.md
 create mode 100755 boot.asm

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..a723f7c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+*.bin
+*.elf
+*.o
+*.img
\ No newline at end of file
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..d6a4490
--- /dev/null
+++ b/README.md
@@ -0,0 +1,52 @@
+# rOSka
+
+Compile with `fasm boot.asm`
+
+## Reguirements
+
+Pentium or newer should have all the bells and whistles needed.
+
+In case you want all the details:
+- 32bit 80386 or newer CPU
+- VGA compatible graphics adapter
+  (640x480 graphics mode with 16 colours and a text mode)
+- BIOS (or CSM, can't take anything granted these days...)
+- RAM as I'm sure I'll just yank hard coded assumptions here and there
+  Like 1MB should be enough for now
+- Hard disk access requires extended BIOS support (i486 CPU?)
+  Youknow, we support big disk like here in modern times.
+- Floppies can't usually be accessed with extended calls, too bad.
+  As a workaround get USB or something and chainload with PLOP bootmgr
+  if direct USB boot is unavailable. Might make a floppy image at some
+  point.
+
+
+## Preparing a bootable disk
+
+- We use standard MBR, even on a floppy. Eat shit MSLosdows.
+- We use partition 1 as our partition. This is ext2. Again, deal with it.
+
+So make a new partition table, partition it, and format it on Lunix.
+Or Losdows, but there you're on your own!
+
+!!! WARNING
+    This will wipe the entire drive
+    Replace /dev/sdX accordingly and triplecheck
+
+```
+sudo parted -s /dev/sdX mklabel msdos
+sudo parted -s /dev/sdX mkpart primary ext2 0 100% --align cylinder
+sudo mkfs.ext2 -L rOSka /dev/sdX1
+```
+
+Now put the thinking part to the MBR preserving partitiontable
+```
+sudo dd bs=1 count=446 if=boot.bin of=/dev/sdX conv=notrunc
+```
+
+And wow, you have a disk with a filesystem that boots the fancy loader
+
+
+```
+TODO: set bootable flag in fdisk and use VBR instead of MBR?
+```
diff --git a/boot.asm b/boot.asm
new file mode 100755
index 0000000..c9f564a
--- /dev/null
+++ b/boot.asm
@@ -0,0 +1,90 @@
+	format binary
+	org 0x7c00
+	use16
+
+	jmp short start
+	nop
+
+	;; reserved for (E)BPB (which BIOS might scramble)
+	;; you could also have one that *could* work
+	times 0x3B db 0
+start:
+
+	;; setup segments
+	;; setup stack
+	;; trust nothing
+	cld
+	mov ax, 0
+	mov ds, ax
+	mov es, ax
+	
+	mov ss, ax
+	mov sp, 0x7c00		;stack down from our load address
+	mov bp, sp
+	
+	;; ensure VGA textmode
+	mov ah, 0x00
+	mov al, 0x03		;Colour Text mode 3 80x25
+	int 0x10
+	
+	;; storeBootdiskNum
+	mov [diskNum], dl
+
+checkLBASupport:
+	;; Set AH = 0x41
+	;; BX = 0x55AA
+	;; DL = drive
+	;; INT 0x13
+
+	mov si, msg.lba
+	mov ah, 0x41
+	mov bx, 0x55AA
+	int 0x13
+
+	jc msg.error
+	test bx, 0xAA55
+	jz msg.error
+	test cx, cx
+	jp msg.error
+
+
+getPartitionLBA:
+	;; 1st partition entry  at 0x1BE (16 bytes)
+	;; LBA start     4bytes at 0x1BE + 0x08
+	;; Sectors count 4bytes at 0x1BE + 0x0C
+
+	;; so uhmmmm, read those and use 'em to find next peace of data?
+	;; Wait is my MBR one block that is read at once? Lol wait MBR
+	;; is also part of my own current loaded memory!
+
+
+
+nomoreThings:
+	mov si, msg.nop
+	jmp msg.ok
+endloop:
+	nop
+	jmp endloop
+	
+msg:
+.ok:
+	mov ah, 0x20		;greenblack
+	jmp .prepare
+.error:
+	mov ah, 0x47		;redgray
+.prepare:
+	mov bx, 0xb800
+	mov es, bx
+	mov edi, 0
+.loop:
+	lodsb
+	test al, al
+	jz endloop
+	stosw
+	jmp .loop
+
+	.lba db "Inadequate LBA support: Ancient computor or floppy?", 0
+	.nop db "Nothingtodo :'(", 0
+
+	;; Store some data
+diskNum db 0x00