1 // license:BSD-3-Clause
2 // copyright-holders:Curt Coder
3 /**********************************************************************
4
5 Epyx Fast Load cartridge emulation
6
7 **********************************************************************/
8
9 #include "emu.h"
10 #include "epyx_fast_load.h"
11
12
13
14 //**************************************************************************
15 // MACROS/CONSTANTS
16 //**************************************************************************
17
18 // t = R*C = 3.3K * 0.47uF * 40% Vtr = 792.2905424610516 usec
19 // (3.3K pull-up on the EXROM line inside the C64, PLA Vih min = 2.0V = 40% of 5.0V)
20 #define TIMER_PERIOD 792
21
22
23
24 //**************************************************************************
25 // DEVICE DEFINITIONS
26 //**************************************************************************
27
28 DEFINE_DEVICE_TYPE(C64_EPYX_FAST_LOAD, c64_epyx_fast_load_cartridge_device, "c64_epyx_fast_load", "C64 Epyx Fast Load cartridge")
29
30
31
32 //**************************************************************************
33 // LIVE DEVICE
34 //**************************************************************************
35
36 //-------------------------------------------------
37 // c64_epyx_fast_load_cartridge_device - constructor
38 //-------------------------------------------------
39
c64_epyx_fast_load_cartridge_device(const machine_config & mconfig,const char * tag,device_t * owner,uint32_t clock)40 c64_epyx_fast_load_cartridge_device::c64_epyx_fast_load_cartridge_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
41 device_t(mconfig, C64_EPYX_FAST_LOAD, tag, owner, clock),
42 device_c64_expansion_card_interface(mconfig, *this), m_exrom_timer(nullptr)
43 {
44 }
45
46
47 //-------------------------------------------------
48 // device_start - device-specific startup
49 //-------------------------------------------------
50
device_start()51 void c64_epyx_fast_load_cartridge_device::device_start()
52 {
53 // allocate timer
54 m_exrom_timer = timer_alloc();
55 }
56
57
58 //-------------------------------------------------
59 // device_reset - device-specific reset
60 //-------------------------------------------------
61
device_reset()62 void c64_epyx_fast_load_cartridge_device::device_reset()
63 {
64 m_exrom = 0;
65 m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
66 }
67
68
69 //-------------------------------------------------
70 // device_timer - handler timer events
71 //-------------------------------------------------
72
device_timer(emu_timer & timer,device_timer_id id,int param,void * ptr)73 void c64_epyx_fast_load_cartridge_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
74 {
75 m_exrom = 1;
76 }
77
78
79 //-------------------------------------------------
80 // c64_cd_r - cartridge data read
81 //-------------------------------------------------
82
c64_cd_r(offs_t offset,uint8_t data,int sphi2,int ba,int roml,int romh,int io1,int io2)83 uint8_t c64_epyx_fast_load_cartridge_device::c64_cd_r(offs_t offset, uint8_t data, int sphi2, int ba, int roml, int romh, int io1, int io2)
84 {
85 if (!roml)
86 {
87 m_exrom = 0;
88 m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
89
90 data = m_roml[offset & 0x1fff];
91 }
92 else if (!io1)
93 {
94 m_exrom = 0;
95 m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
96 }
97 else if (!io2)
98 {
99 data = m_roml[offset & 0x1fff];
100 }
101
102 return data;
103 }
104
105
106 //-------------------------------------------------
107 // c64_cd_w - cartridge data write
108 //-------------------------------------------------
109
c64_cd_w(offs_t offset,uint8_t data,int sphi2,int ba,int roml,int romh,int io1,int io2)110 void c64_epyx_fast_load_cartridge_device::c64_cd_w(offs_t offset, uint8_t data, int sphi2, int ba, int roml, int romh, int io1, int io2)
111 {
112 if (!io1)
113 {
114 m_exrom = 0;
115 m_exrom_timer->adjust(attotime::from_usec(TIMER_PERIOD), 0);
116 }
117 }
118