Adding machine IBM System/23 Datamaster (system23.cpp, non-working); its keyboard; corrections to Intel 8275

src/devices/video/i8275.cpp

@@ -27,7 +27,6 @@
     TODO:
 
     - double spaced rows
-    - preset counters - how it affects DMA and HRTC?
 
 */
 
@@ -62,7 +61,7 @@ const int i8275_device::character_attribute[3][16] =
 // device type definitions
 DEFINE_DEVICE_TYPE(I8275, i8275_device, "i8275", "Intel 8275 CRTC")
 DEFINE_DEVICE_TYPE(I8276, i8276_device, "i8276", "Intel 8276 CRTC")
-
+DEFINE_DEVICE_TYPE(IBM4178629, ibm4178629_device, "ibm4178629", "IBM 418629 CRTC")
 
 
 //**************************************************************************
@@ -96,13 +95,16 @@ i8275_device::i8275_device(const machine_config &mconfig, device_type type, cons
 	m_buffer_dma(0),
 	m_lpen(0),
 	m_scanline(0),
+	m_column(0),
 	m_dma_stop(false),
 	m_end_of_screen(false),
 	m_preset(false),
 	m_cursor_blink(0),
 	m_char_blink(0),
 	m_stored_attr(0),
-	m_field_attr(0)
+	m_field_attr(0),
+	m_ibmCRTC(false),
+	m_init(false)
 {
 	memset(m_param, 0x00, sizeof(m_param));
 }
@@ -117,6 +119,12 @@ i8276_device::i8276_device(const machine_config &mconfig, const char *tag, devic
 {
 }
 
+ibm4178629_device::ibm4178629_device(const machine_config &mconfig, const char * tag, device_t *owner, uint32_t clock) :
+	i8275_device(mconfig, IBM4178629, tag, owner, clock)
+{
+	this->m_ibmCRTC = true;
+}
+
 
 void i8275_device::device_resolve_objects()
 {
@@ -145,6 +153,13 @@ void i8275_device::device_start()
 		m_scanline_timer = timer_alloc(FUNC(i8275_device::scanline_tick), this);
 	}
 
+	//preinitialize the device with valid data (in real hardware parameters initialize to random)
+	m_param[REG_SCN1] = 0x4f;
+	m_param[REG_SCN2] = 0x58;
+	m_param[REG_SCN3] = 0x89;
+	m_param[REG_SCN4] = 0xd9;
+	recompute_parameters();
+
 	// state saving
 	save_item(NAME(m_status));
 	save_item(NAME(m_param));
@@ -161,6 +176,7 @@ void i8275_device::device_start()
 	save_item(NAME(m_buffer_dma));
 	save_item(NAME(m_lpen));
 	save_item(NAME(m_scanline));
+	save_item(NAME(m_column));
 	save_item(NAME(m_irq_scanline));
 	save_item(NAME(m_vrtc_scanline));
 	save_item(NAME(m_vrtc_drq_scanline));
@@ -171,6 +187,8 @@ void i8275_device::device_start()
 	save_item(NAME(m_char_blink));
 	save_item(NAME(m_stored_attr));
 	save_item(NAME(m_field_attr));
+	save_item(NAME(m_ibmCRTC));
+	save_item(NAME(m_init));
 }
 
 
@@ -298,8 +316,10 @@ TIMER_CALLBACK_MEMBER(i8275_device::scanline_tick)
 	{
 		for (i8275_device *crtc = this; crtc != nullptr; crtc = crtc->m_next_crtc)
 		{
-			if ((crtc->m_status & ST_IE) && !(crtc->m_status & ST_IR))
+			// If either the IC is initialized or it is an IBM CRTC the interrupt is set if the EI flag is set
+			if ((crtc->m_status & ST_IE) && !(crtc->m_status & ST_IR) && (crtc->m_init || crtc->m_ibmCRTC))
 			{
+				LOG("I8275 IRQ Set\n");
 				crtc->m_status |= ST_IR;
 				crtc->m_write_irq(ASSERT_LINE);
 			}
@@ -358,6 +378,7 @@ TIMER_CALLBACK_MEMBER(i8275_device::scanline_tick)
 				auto [data, attr] = crtc->char_from_buffer(n, sx, rc, lc, end_of_row, blank_row);
 				charcode |= uint32_t(data) << (n * 8);
 				attrcode |= uint32_t(attr) << (n * 8);
+				crtc->m_column = sx;
 			}
 
 			m_display_cb(m_bitmap,
@@ -410,6 +431,7 @@ std::pair<uint8_t, uint8_t> i8275_device::char_from_buffer(int n, int sx, int rc
 		{
 			// simply blank the attribute character itself
 			attr = FAC_B;
+			attr |= (data & FAC_GG); // add the GG attributes
 		}
 	}
 	else if (data >= 0xf0 || BIT(end_of_row, n))
@@ -562,7 +584,7 @@ void i8275_device::write(offs_t offset, uint8_t data)
 		 */
 		case CMD_RESET:
 			LOG("I8275 Reset\n");
-
+			m_init = true;
 			m_status &= ~(ST_IE | ST_IR | ST_VE);
 			LOG("I8275 IRQ 0\n");
 			m_write_irq(CLEAR_LINE);
@@ -716,8 +738,8 @@ void i8275_device::lpen_w(int state)
 {
 	if (!m_lpen && state)
 	{
-		m_param[REG_LPEN_COL] = screen().hpos() / m_hpixels_per_column;
-		m_param[REG_LPEN_ROW] = screen().vpos() / scanlines_per_row();
+		m_param[REG_LPEN_COL] = m_column + 3; //According to the datasheet the column is at least three positions off
+		m_param[REG_LPEN_ROW] = m_scanline / scanlines_per_row();
 
 		m_status |= ST_LP;
 	}

src/devices/video/i8275.h

@@ -233,6 +233,7 @@ class i8275_device :   public device_t,
 	int m_lpen;
 
 	int m_scanline;
+	int m_column;
 	int m_irq_scanline;
 	int m_vrtc_scanline;
 	int m_vrtc_drq_scanline;
@@ -245,6 +246,9 @@ class i8275_device :   public device_t,
 	uint8_t m_stored_attr;
 	uint8_t m_field_attr;
 
+	bool m_ibmCRTC;
+	bool m_init;
+
 	// timers
 	emu_timer *m_hrtc_on_timer;
 	emu_timer *m_drq_on_timer;
@@ -258,9 +262,16 @@ class i8276_device : public i8275_device
 	i8276_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
 };
 
+class ibm4178629_device : public i8275_device
+{
+public:
+	ibm4178629_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
+};
+
 
 // device type definition
 DECLARE_DEVICE_TYPE(I8275, i8275_device)
 DECLARE_DEVICE_TYPE(I8276, i8276_device)
+DECLARE_DEVICE_TYPE(IBM4178629, ibm4178629_device)
 
 #endif // MAME_VIDEO_I8275_H