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lwriter.cpp: Elaborate the documentation of some of the VIA pins (#8423)

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Jeff Muizelaar 2021-08-11 16:15:11 -04:00 committed by GitHub
parent 6f04b2f221
commit 7b359e1939
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1 changed files with 12 additions and 2 deletions
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src/mame/drivers/lwriter.cpp
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@ -378,7 +378,7 @@ void lwriter_state::fifo_out_w(uint8_t data)
* 1 - print sbsy * 1 - print sbsy
* 2 - ? * 2 - ?
* 3 - ? * 3 - ?
* 4 - some print thing * 4 - print vsreq
* 5 - switch setting low * 5 - switch setting low
* 6 - switch setting high * 6 - switch setting high
* 7 - print (STATUS/COMMAND Message Line) * 7 - print (STATUS/COMMAND Message Line)
@ -411,13 +411,23 @@ WRITE_LINE_MEMBER(lwriter_state::via_ca2_w)
logerror(" VIA: CA2 written with %d!\n", state); logerror(" VIA: CA2 written with %d!\n", state);
} }
/* via port b bits:
* 0 - ?
* 1 - print rdy
* 2 - print pprdy
* 3 - overlay
* 4 -
* 5 -
* 6 - timer 2 clk
* 7 - print related timing thing
*/
uint8_t lwriter_state::via_pb_r() uint8_t lwriter_state::via_pb_r()
{ {
logerror(" VIA: Port B read!\n"); logerror(" VIA: Port B read!\n");
return 0xFB; return 0xFB;
} }
// The 3rd bit is used for talking with the print controller // The 3rd bit (PPRDY) is used for talking with the print controller
// and is inverted on II NT // and is inverted on II NT
uint8_t lwriter_state::via_pb_lw2nt_r() uint8_t lwriter_state::via_pb_lw2nt_r()
{ {