summaryrefslogtreecommitdiffstatshomepage
path: root/src/mame/drivers/votrtnt.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/mame/drivers/votrtnt.cpp')
-rw-r--r--src/mame/drivers/votrtnt.cpp18
1 files changed, 12 insertions, 6 deletions
diff --git a/src/mame/drivers/votrtnt.cpp b/src/mame/drivers/votrtnt.cpp
index c8751fb71af..8299cf63223 100644
--- a/src/mame/drivers/votrtnt.cpp
+++ b/src/mame/drivers/votrtnt.cpp
@@ -68,11 +68,17 @@ private:
******************************************************************************/
/* a15 a14 a13 a12 a11 a10 a9 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)
+ 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)
+ 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
+ x 1 1 x * * * * * * * * * * * * R ROM (2332 4kx8 Mask ROM, inside potted brick)
*/
static ADDRESS_MAP_START(6802_mem, AS_PROGRAM, 8, votrtnt_state)
@@ -80,7 +86,7 @@ static ADDRESS_MAP_START(6802_mem, AS_PROGRAM, 8, votrtnt_state)
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(0x4000, 0x4000) AM_MIRROR(0x9fff) AM_DEVWRITE("votrax", votrax_sc01_device, write)
AM_RANGE(0x6000, 0x6fff) AM_MIRROR(0x9000) AM_ROM /* ROM in potted block */
ADDRESS_MAP_END