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this has cluttered the source for quite long enough, clean up this old mess of mine... (nw)

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Lord-Nightmare 2017-08-09 23:35:39 -04:00
parent c631f59f50
commit 554a1517c3
1 changed files with 32 additions and 45 deletions
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77
src/mame/drivers/votrpss.cpp
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@ -9,52 +9,39 @@
*
* The votrax PSS was sold from around 35th week of 1982 until october, 1990 (LONG product life)
<kevtris> timer0 = baud clock
<kevtris> timer1 = pitch (duty cycle output to modify RC)
<kevtris> timer2 = volume (duty cycle output to control trans. gate which does vol. control)
<kevtris> portb: pin 6 through pin 13 of parallel port
<kevtris> portc 0 = NC, 1 = GND, 2 = pin 5, 3 = /RXINTEN, 4 = pin 15, 5 = pin 14 through inverter, 6 = 8910 enable, 7 = from pin 4 through inverter (I believe that's for the parallel port)
<kevtris> porta: pin 16 through 23 of parallel port
<kevtris> that's the 8255
<kevtris> on the AY-3-8910:
<kevtris> IOA0-A5 = phoneme #
<kevtris> IOA6 = strobe (SC-01)
<kevtris> IOA7 = vochord control, 0 = off, 1 = on
<kevtris> IOB0-IOB7 = dip switches
<kevtris> there ya go, complete IO port map
<LordNLptp> cool :)
<kevtris> I pinned the IO to the serial port from the 8251 but I don't think it's too useful
<LordNLptp> eh, its useful
<kevtris> I drew out the schematic for the analog section
<LordNLptp> oh that will be useful
<kevtris> but I didn't draw out the digital part, just made an I/O and memory map but I can't find them
<LordNLptp> i also see the ay is running at 2 MHz
<kevtris> sounds about right
<kevtris> got it
<kevtris> I drew out the clocking section too
<kevtris> 8MHz xtal
<kevtris> 4MHz for the Z80
<kevtris> 2MHz for the 8253 and '8910
<kevtris> then the dividers also generate the system reset signals for the 8251
<kevtris> and a periodic IRQ
<LordNLptp> on the z80?
<LordNLptp> ok how does that work?
<kevtris> IRQ rate is umm
<kevtris> 122Hz
<kevtris> (8MHz / 65536)
<kevtris> oh the 8251 is not reset by the counters
<kevtris> it just takes a positive reset off an inverter that resets the counters
<kevtris> PIT2 is gated by 8MHz / 256
<kevtris> PIT1 is gated by 8MHz / 4096
<kevtris> PIT0 is not gated
<kevtris> (i.e. it always runs)
<LordNLptp> oh boy, this is sounding more fun by the minute
<kevtris> aaand your luck is about to run out
<kevtris> that's all I got
<LordNLptp> thats good enough, saved me a lot of work
<kevtris> but that's everything you need
<LordNLptp> yeah
Main xtal is 8MHz
AY-3-8910 and i8253 clock is running at 2 MHz (xtal/4)
Z80A is runing at 4MHz (xtal/2)
clock dividers also generate the system reset signals for the 8251 and and a periodic IRQ at 122Hz (xtal/65536)
I8253:
Timer0 = Baud Clock, not gated (constantly on)
Timer1 = output to transistor chopper on clock input to sc-01-a to control pitch; gated by xtal/256
Timer2 = output to transistor chopper on output of sc-01-a to control volume; gated by xtal/4096
I8255 ports:
PortA 0:7 = pins 16 thru 23 of parallel port
PortB 0:7 = pins 6 thru 13 of parallel port
PortC =
0 = NC
1 = GND
2 = pin 5 of parallel port
3 = /RXINTEN
4 = pin 15 of parallel port
5 = pin 14 of parallel port through inverter
6 = ay-3-8910 enable (which pin? BC1?)
7 = input from parallel port pin 4 through inverter
AY-3-8910 I/O ports:
IOA is in output mode
IOA0-A5 = phoneme #
IOA6 = strobe (SC-01)
IOA7 = vochord control, 0 = off, 1 = on
IOB is in input mode
IOB0-IOB7 = dip switches
I8251 UART:
RESET is taken from teh same inverter that resets the counters
Things to be looked at:
- Serial doesn't work, so has been disabled.