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r14908 Saturday 14th April, 2012 at 03:40:51 UTC by R. Belmont
Apple II SCSI: figured out card memory mapping some more, checking in to "back up" that documentation (nw)

[src/mess/machine]

a2scsi.c a2scsi.h

src/mess/machine/a2scsi.c

r14907	r14908
10	10
11	11	Notes:
12	12
13		PAL U3C:
14		I1 = A0
15		I2 = A1
16		I3 = A2
17		I4 = A3
18		I5 = O2 of PAL U3D
19		I6 = (logic maze)
20		I7 = R/W (also I7 of PAL U3D)
21		I8 = PHI0 (via flip flops)
22		I9 = RESET
23		I10 = GND
	13	C0n0-C0n7 = NCR5380 registers in normal order
	14	C0n9 = DIP switches
	15	C0na = RAM and ROM bank switching
	16	C0nb = reset 5380
	17	C0ne = into the PAL stuff
24	18
25		O1 = P on flip-flops U6DA/U6DB, I8 on PAL U3D
26		O2 = N/C
27		O3 = I6 on PAL U3D
28		O4 = N/C
29		O5 = /CS on NCR 5380
30		O6 = /WR on NCR 5380
31		O7 = /RD on NCR 5380
32		O8 = /DACK on NCR 5380
33
34		PAL U3D:
35		I1 = A0-A10 NANDed together (goes low on CFFF access, i.e.)
36		I2 = /IOSTB
37		I3 = /IOSEL
38		I4 = RESET
39		I5 = A10 (splits C800 space at C800/CC00)
40		I6 = O3 of PAL U3C
41		I7 = R/W
42		I8 = O1 of PAL U3C
43		I9 = DRQ from 5380
44		I10 = Y6 from 74LS138 at U3D (C0n6 access)
45
46		O1 = G on 74LS245 main data bus buffer
47		O2 = I5 of PAL U3C
48		O3 = D to flip-flop at U6DB
49		O4 = CLK to flip-flop at U6DA
50		O5 = D7 (?)
51		O6 = CS1 on RAM
52		O7 = EPROM CE
53		O8 = EPROM OE
54
55	19	*********************************************************************/
56	20
57	21	#include "a2scsi.h"
r14907	r14908
124	88
125	89	a2bus_scsi_device::a2bus_scsi_device(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, UINT32 clock) :
126	90	device_t(mconfig, type, name, tag, owner, clock),
127		device_a2bus_card_interface(mconfig, *this)
	91	device_a2bus_card_interface(mconfig, *this),
	92	m_ncr5380(*this, SCSI_5380_TAG)
128	93	{
129	94	m_shortname = "a2scsi";
130	95	}
131	96
132	97	a2bus_scsi_device::a2bus_scsi_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) :
133	98	device_t(mconfig, A2BUS_SCSI, "Apple II SCSI Card", tag, owner, clock),
134		device_a2bus_card_interface(mconfig, *this)
	99	device_a2bus_card_interface(mconfig, *this),
	100	m_ncr5380(*this, SCSI_5380_TAG)
135	101	{
136	102	m_shortname = "a2scsi";
137	103	}
r14907	r14908
161	127	read_c0nx - called for reads from this card's c0nx space
162	128	-------------------------------------------------*/
163	129
164		/*
165
166		From schematic (decoded by 74LS138 at U2D)
167
168		C0n1/9 = DIP switches
169		C0n2/a = clock to 74LS273 bank switcher (so data here should be the bank)
170		C0n3/b = reset 5380
171		C0n6/e = into the PAL stuff
172
173		*/
174
175	130	UINT8 a2bus_scsi_device::read_c0nx(address_space &space, UINT8 offset)
176	131	{
177	132	printf("Read c0n%x (PC=%x)\n", offset, cpu_get_pc(&space.device()));
178	133
	134	switch (offset)
	135	{
	136	case 0:
	137	case 1:
	138	case 2:
	139	case 3:
	140	case 4:
	141	case 5:
	142	case 6:
	143	case 7:
	144	return ncr5380_read_reg(m_ncr5380, offset);
	145
	146	case 9:         // card's ID?
	147	return 7;
	148	}
	149
179	150	return 0xff;
180	151	}
181	152
r14907	r14908
188	159	{
189	160	printf("Write %02x to c0n%x (PC=%x)\n", data, offset, cpu_get_pc(&space.device()));
190	161
191		switch (offset & 7)
	162	switch (offset)
192	163	{
193		case 0x2:   // ROM and RAM banking (74LS273 at U3E)
	164	case 0:
	165	case 1:
	166	case 2:
	167	case 3:
	168	case 4:
	169	case 5:
	170	case 6:
	171	case 7:
	172	ncr5380_write_reg(m_ncr5380, offset, data);
	173	break;
	174
	175	case 0xa:  // ROM and RAM banking (74LS273 at U3E)
194	176	/*
195	177	ROM banking:
196	178	(bits EA8-EA13 are all zeroed when /IOSEL is asserted, so CnXX always gets the first page of the ROM)
r14907	r14908
209	191	m_rombank = (data & 0xf) * 0x400;
210	192	printf("RAM bank to %x, ROM bank to %x\n", m_rambank, m_rombank);
211	193	break;
	194
	195	case 0xb:
	196	printf("Reset NCR5380\n");
	197	break;
212	198	}
213	199	}
214	200

src/mess/machine/a2scsi.h

r14907	r14908
42	42	virtual UINT8 read_c800(address_space &space, UINT16 offset);
43	43	virtual void write_c800(address_space &space, UINT16 offset, UINT8 data);
44	44
	45	required_device<device_t> m_ncr5380;
	46
45	47	private:
46	48	UINT8 *m_rom;
47	49	UINT8 m_ram[8192];  // 8 banks of 1024 bytes

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