diff options
Diffstat (limited to 'src/mame/includes/bbc.h')
-rw-r--r-- | src/mame/includes/bbc.h | 74 |
1 files changed, 37 insertions, 37 deletions
diff --git a/src/mame/includes/bbc.h b/src/mame/includes/bbc.h index d21d24839f1..b53a469ccd4 100644 --- a/src/mame/includes/bbc.h +++ b/src/mame/includes/bbc.h @@ -313,22 +313,22 @@ public: // HACK FOR MC6845 bool m_lk19_ic37_paged_rom; // BBC Master Paged ROM/RAM select IC37 /* - ACCCON - b7 IRR 1=Causes an IRQ to the processor - b6 TST 1=Selects &FC00-&FEFF read from OS-ROM - b5 IFJ 1=Internal 1 MHz bus - 0=External 1MHz bus - b4 ITU 1=Internal Tube - 0=External Tube - b3 Y 1=Read/Write HAZEL &C000-&DFFF RAM - 0=Read/Write ROM &C000-&DFFF OS-ROM - b2 X 1=Read/Write LYNNE - 0=Read/WRITE main memory &3000-&8000 - b1 E 1=Causes shadow if VDU code - 0=Main all the time - b0 D 1=Display LYNNE as screen - 0=Display main RAM screen - ACCCON is a read/write register + ACCCON + b7 IRR 1=Causes an IRQ to the processor + b6 TST 1=Selects &FC00-&FEFF read from OS-ROM + b5 IFJ 1=Internal 1 MHz bus + 0=External 1MHz bus + b4 ITU 1=Internal Tube + 0=External Tube + b3 Y 1=Read/Write HAZEL &C000-&DFFF RAM + 0=Read/Write ROM &C000-&DFFF OS-ROM + b2 X 1=Read/Write LYNNE + 0=Read/WRITE main memory &3000-&8000 + b1 E 1=Causes shadow if VDU code + 0=Main all the time + b0 D 1=Display LYNNE as screen + 0=Display main RAM screen + ACCCON is a read/write register */ int m_acccon; @@ -343,27 +343,27 @@ public: // HACK FOR MC6845 /* - The addressable latch - This 8 bit addressable latch is operated from port B lines 0-3. - PB0-PB2 are set to the required address of the output bit to be set. - PB3 is set to the value which should be programmed at that bit. - The function of the 8 output bits from this latch are:- - - B0 - Write Enable to the sound generator IC - B1 - READ select on the speech processor (B and B+) - R/nW control on CMOS RAM (Master only) - B2 - WRITE select on the speech processor - DS control on CMOS RAM (Master only) - B3 - Keyboard write enable - B4,B5 - these two outputs define the number to be added to the - start of screen address in hardware to control hardware scrolling:- - Mode Size Start of screen Size No.to add B5 B4 - 0,1,2 20K &3000 12K 1 1 - 3 16K &4000 16K 0 0 - 4,5 10K &5800 (or &1800) 22K 1 0 - 6 8K &6000 (or &2000) 24K 0 1 - B6 - Operates the CAPS lock LED (Pin 17 keyboard connector) - B7 - Operates the SHIFT lock LED (Pin 16 keyboard connector) + The addressable latch + This 8 bit addressable latch is operated from port B lines 0-3. + PB0-PB2 are set to the required address of the output bit to be set. + PB3 is set to the value which should be programmed at that bit. + The function of the 8 output bits from this latch are:- + + B0 - Write Enable to the sound generator IC + B1 - READ select on the speech processor (B and B+) + R/nW control on CMOS RAM (Master only) + B2 - WRITE select on the speech processor + DS control on CMOS RAM (Master only) + B3 - Keyboard write enable + B4,B5 - these two outputs define the number to be added to the + start of screen address in hardware to control hardware scrolling:- + Mode Size Start of screen Size No.to add B5 B4 + 0,1,2 20K &3000 12K 1 1 + 3 16K &4000 16K 0 0 + 4,5 10K &5800 (or &1800) 22K 1 0 + 6 8K &6000 (or &2000) 24K 0 1 + B6 - Operates the CAPS lock LED (Pin 17 keyboard connector) + B7 - Operates the SHIFT lock LED (Pin 16 keyboard connector) */ int m_b0_sound; |