more sane directory name, updated binaries

src/kernal/iec/iec_tx_command.s

@@ -0,0 +1,46 @@
+// #LAYOUT# STD *        #TAKE
+// #LAYOUT# *   KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+// Implemented based on https://www.pagetable.com/?p=1135, https://github.com/mist64/cbmbus_doc
+
+// Expects byte to send in TBTCNT ($A4 is a byte buffer according to http://sta.c64.org/cbm64mem.html)
+// Carry flag set = signal EOI
+//
+// Preserves .X and .Y registers
+
+
+#if CONFIG_IEC
+
+
+iec_tx_command:
+
+	// Store .X and .Y on the stack - preserve them
+	phx_trash_a
+	phy_trash_a
+
+	// Notify all devices that we are going to send a byte
+	// and it is going to be a command (pulled ATN)
+	jsr iec_pull_atn_clk_release_data
+
+	// Give devices time to respond (response is mandatory!) by pulling DATA
+	jsr iec_wait1ms
+	lda CIA2_PRA // pulled DATA = highest bit 0 = 'plus'
+	bpl !+
+	jmp iec_return_DEVICE_NOT_FOUND
+!:
+	// At least one device responded, but they are still allowed to stall
+	// (can be busy processing something), we have to wait till they are all
+	// ready (or bored with DOS attack...)
+	// Release back CLK, keep DATA released - to ask devices for status.
+
+	jsr iec_release_clk_data
+
+	// Common part of iec_txbyte and iec_tx_common - waits for devices
+	// and transmits a byte
+
+	clc // Carry flag set is used for EOI mark
+	jmp iec_tx_common
+
+
+#endif // CONFIG_IEC