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Votrax TNT: fixed the memory map mirroring based on schematic. [Lord Nightmare, Kevtris]

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Lord-Nightmare 2015-10-11 01:28:19 -04:00
parent 9cb770e66d
commit 1122d70d17
1 changed files with 15 additions and 8 deletions
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23
src/mame/drivers/votrtnt.c
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@ -64,23 +64,30 @@ private:
Address Maps
******************************************************************************/
/* a15 a14 a13 a12 a11 a10 a09 a8 a7 a6 a5 a4 a3 a2 a1 a0
x 0 0 x x x * * * * * * * * * * RW RAM (2x 2114 1kx4 SRAM, wired in parallel)
x 0 1 x x x x x x x x x x x x 0 RW 6850 Status(R)/Control(W)
x 0 1 x x x x x x x x x x x x 1 RW 6850 Data(R)/Data(W)
x 1 0 x x x x x x x x x x x x x W SC-01 Data(W)
x 1 1 x * * * * * * * * * * * * R ROM (2332 4kx8 Mask ROM, inside potted brick)
*/
static ADDRESS_MAP_START(6802_mem, AS_PROGRAM, 8, votrtnt_state)
ADDRESS_MAP_UNMAP_HIGH
ADDRESS_MAP_GLOBAL_MASK(0x6fff)
AM_RANGE(0x0000, 0x03ff) AM_RAM AM_MIRROR(0xc00)/* RAM, 2114*2 (0x400 bytes) mirrored 4x */
AM_RANGE(0x2000, 0x2000) AM_MIRROR(0xffe) AM_DEVREADWRITE("acia", acia6850_device, status_r, control_w)
AM_RANGE(0x2001, 0x2001) AM_MIRROR(0xffe) AM_DEVREADWRITE("acia", acia6850_device, data_r, data_w)
AM_RANGE(0x4000, 0x5fff) AM_DEVWRITE("votrax", votrax_sc01_device, write) /* low 6 bits write to 6 bit input of sc-01-a; high 2 bits are ignored (but by adding a buffer chip could be made to control the inflection bits of the sc-01-a which are normally grounded on the tnt) */
AM_RANGE(0x6000, 0x6fff) AM_ROM /* ROM in potted block */
AM_RANGE(0x0000, 0x03ff) AM_MIRROR(0x9c00) AM_RAM /* RAM, 2114*2 (0x400 bytes) mirrored 4x */
AM_RANGE(0x2000, 0x2000) AM_MIRROR(0x9ffe) AM_DEVREADWRITE("acia", acia6850_device, status_r, control_w)
AM_RANGE(0x2001, 0x2001) AM_MIRROR(0x9ffe) AM_DEVREADWRITE("acia", acia6850_device, data_r, data_w)
AM_RANGE(0x4000, 0x4000) AM_MIRROR(0x9fff) AM_DEVWRITE("votrax", votrax_sc01_device, write) /* low 6 bits write to 6 bit input of sc-01-a; high 2 bits are ignored (but by adding a buffer chip could be made to control the inflection bits of the sc-01-a which are normally grounded on the TNT); upon any access to this area (even reads, which count effectively as a 'write of open bus value') the /STB line of the sc-01 is pulsed low using a 74123 monostable multivibrator with a capacitor of 120pf and a resistor to vcc of 22Kohm */
AM_RANGE(0x6000, 0x6fff) AM_MIRROR(0x9000) AM_ROM /* ROM in potted block */
ADDRESS_MAP_END
/******************************************************************************
Input Ports
******************************************************************************/
/** TODO: actually hook this up to the ACIA */
static INPUT_PORTS_START(votrtnt)
PORT_START("DSW1") /* not connected to cpu, each switch is connected directly to the output of a 4040 counter dividing the cpu m1? clock to feed the 6850 ACIA. Setting more than one switch on is a bad idea. see tnt_schematic.jpg */
PORT_START("DSW1") /* not connected to cpu, each switch is connected directly to the output of a 4040 counter dividing the cpu m1? clock to feed the 6850 ACIA. Setting more than one switch on (downward is on, upward is off) is a bad idea, as it will short together outputs of the 4040, possibly damaging it. see tnt_schematic.jpg */
PORT_DIPNAME( 0xFF, 0x80, "Baud Rate" ) PORT_DIPLOCATION("SW1:1,2,3,4,5,6,7,8")
PORT_DIPSETTING( 0x01, "75" )
PORT_DIPSETTING( 0x02, "150" )