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author Ivan Vangelista <mesgnet@yahoo.it>2020-03-21 21:19:28 +0100
committer Ivan Vangelista <mesgnet@yahoo.it>2020-03-21 21:19:28 +0100
commit326e93e62d75d1711f6a70cabfa7fea118172a1e (patch)
tree1d118bb1653496f34c94363875de5864748ae0c7
parent21ede04ecd987647b5922ee3a8c61da02ba623e0 (diff)
20pacgal.cpp: measured CPU clock and updated comments [Guru]
-rw-r--r--src/mame/drivers/20pacgal.cpp11
1 files changed, 5 insertions, 6 deletions
diff --git a/src/mame/drivers/20pacgal.cpp b/src/mame/drivers/20pacgal.cpp
index 3cab84c4a2a..f72bce8aa23 100644
--- a/src/mame/drivers/20pacgal.cpp
+++ b/src/mame/drivers/20pacgal.cpp
@@ -44,8 +44,7 @@
* Check the ASCI interface, there probably is fully working debug code.
* The timed interrupt is a kludge; it is supposed to be generated internally by
the Z180, but the cpu core doesn't support that yet.
- * Is the clock divide 3 or 4?
- * Galaga attract mode isn't correct; referenct : https://youtu.be/OQyWaN9fTgw?t=2m33s
+ * Galaga attract mode isn't correct; reference : https://youtu.be/OQyWaN9fTgw?t=2m33s
+-------------------------------------------------------+
| +-------------+ |
@@ -73,14 +72,14 @@
| D4 +-------------+ +-------+ |
+-------------------------------------------------------+
- CPU: Z8S18020VSC ZiLOG Z180 (20MHz part)
+ CPU: Z8S18020VSC ZiLOG Z180 (20MHz part) at 18.432MHz
Graphics: CY37256P160-83AC x 2 (Ultra37000 CPLD family - 160 pin TQFP, 256 Macrocells, 83MHz speed)
MEMORY: CY7C199-15VC 32K x 8 Static RAM x 3 (or equivalent ISSI IS61C256AH-15J)
OSC: 73.728MHz
EEPROM: 93LC46A 128 x 8-bit 1K microwire compatible Serial EEPROM
VOL: Volume adjust
D4: Diode - Status light
- J1: 5 2-pin jumper array
+ J1: 10 pin JTAG interface for programming the CY37256P160 CPLDs
***************************************************************************/
@@ -102,7 +101,7 @@ Graphics: CY37256P160-83AC x 2 (Ultra37000 CPLD family - 160 pin TQFP, 256 Macro
*************************************/
#define MASTER_CLOCK (XTAL(73'728'000))
-#define MAIN_CPU_CLOCK (MASTER_CLOCK / 2)
+#define MAIN_CPU_CLOCK (MASTER_CLOCK / 2) // divided by 2 internally in the Z180 core
#define NAMCO_AUDIO_CLOCK (MASTER_CLOCK / 4 / 6 / 32)
@@ -400,7 +399,7 @@ WRITE_LINE_MEMBER(_20pacgal_state::vblank_irq)
void _20pacgal_state::_20pacgal(machine_config &config)
{
/* basic machine hardware */
- Z8S180(config, m_maincpu, MAIN_CPU_CLOCK);
+ Z8S180(config, m_maincpu, MAIN_CPU_CLOCK); // 18.432MHz verified on PCB
m_maincpu->set_addrmap(AS_PROGRAM, &_20pacgal_state::_20pacgal_map);
m_maincpu->set_addrmap(AS_IO, &_20pacgal_state::_20pacgal_io_map);