From 8a031b1137d6d1692b3a74260eb21c7db724ec0f Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 16 May 2018 22:09:59 -0400
Subject: [PATCH] Eliminates 'data' register as it doesn't exist; rejigs state
 machine command set.

---
 Components/DiskII/DiskII.cpp | 14 +++++++++-----
 Components/DiskII/DiskII.hpp |  1 -
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/Components/DiskII/DiskII.cpp b/Components/DiskII/DiskII.cpp
index 838ce569c..94379045c 100644
--- a/Components/DiskII/DiskII.cpp
+++ b/Components/DiskII/DiskII.cpp
@@ -84,7 +84,7 @@ void DiskII::select_drive(int drive) {
 void DiskII::set_data_register(uint8_t value) {
 //	printf("Set data register (?)\n");
 	inputs_ |= input_command;
-	data_register_ = value;
+//	shift_register_ = value;
 	set_controller_can_sleep();
 }
 
@@ -106,15 +106,20 @@ void DiskII::run_for(const Cycles cycles) {
 			inputs_ |= input_flux;
 			state_ = state_machine_[static_cast<std::size_t>(address)];
 			switch(state_ & 0xf) {
-				case 0x0:	shift_register_ = 0;													break;	// clear
+				default:	shift_register_ = 0;													break;	// clear
+				case 0x8:																			break;	// nop
+
 				case 0x9:	shift_register_ = static_cast<uint8_t>(shift_register_ << 1);			break;	// shift left, bringing in a zero
 				case 0xd:	shift_register_ = static_cast<uint8_t>((shift_register_ << 1) | 1);		break;	// shift left, bringing in a one
-				case 0xb:	shift_register_ = data_register_;										break;	// load
 
 				case 0xa:	// shift right, bringing in write protected status
 					shift_register_ = (shift_register_ >> 1) | (is_write_protected() ? 0x80 : 0x00);
 				break;
-				default: break;
+				case 0xb:
+					// load data register from data bus...
+					printf("TODO\n");
+				//	shift_register_ = data_register_;
+				break;	// load
 			}
 
 			// TODO: surely there's a less heavyweight solution than this?
@@ -139,7 +144,6 @@ void DiskII::set_controller_can_sleep() {
 }
 
 bool DiskII::is_write_protected() {
-return true;
 	return !!(stepper_mask_ & 2) | drives_[active_drive_].get_is_read_only();
 }
 
diff --git a/Components/DiskII/DiskII.hpp b/Components/DiskII/DiskII.hpp
index 9c5932c84..14a714b71 100644
--- a/Components/DiskII/DiskII.hpp
+++ b/Components/DiskII/DiskII.hpp
@@ -65,7 +65,6 @@ class DiskII:
 		uint8_t state_ = 0;
 		uint8_t inputs_ = 0;
 		uint8_t shift_register_ = 0;
-		uint8_t data_register_ = 0;
 
 		int stepper_mask_ = 0;
 		int stepper_position_ = 0;