max.pendragon@pro-lep.cts.com (Max Pendragon) (10/13/90)
Andy,
On your 8-bit screen blanker, check the Apple //c reference manual, vol 1,
pages 26-47 for more info on the soft switches. You can read the state of all
(?) of the soft switches, including the state of memory, which you will need
if you run in an alternate bank. here's a quicky run-down
The first column is the type of instruction required to activate the switch.
R= read, W = Write, RR = read twice in a row, R7 = read bit 7 for status.
Action Addr Name Function
R $c080 read ram, no write, $d000 bank 2
RR $c081 read rom, write ram, $d000 bank 2
R $c082 read rom, no write, $d000 bank 2
RR $c083 read/write RAM, $d000 bank 2
R $c088 read ram, no write, use $d000 bank 1
RR $c089 read rom, write RAM use $d000 bank 1
R $c08a read rom, no write use $d000 bank 1
RR $c08b read/write RAM use $d000 bank 1
R7 $c011 RDBNK2 state of $d000 (0=bank 1, 1=bank2)
R7 $c012 RDLCRAM rreading RAM (1) or ROM (0)
W $c008 ALTZP aux zpage off (pages 0,1, and lang card?)
W $c009 ALTZP aux zpage on (pages 0,1, and lang card?)
R7 $c016 RDALTZP using aux(1) or main(0) zpage
W $c002 RAMRD read main 48K ram
W $c003 RAMRD "on" read aux 48K ram
R7 $c013 RDRAMRD using main (0) or aux(1) main 48K
W $c004 RAMWRT write to main 48K ram
W $c005 RAMWRT "on" write to aux 48K ram
R7 $c014 RDRAMWRT using main(o) or aux (1) main 48K ram
R $c050 use graphics screen
R $c051 use text screen
R $c054 use page 1 (txt or graphics)
R $c055 use page 2 (txt or graphics)
R $c056 hi-res off (txt or low-res on)
R $c057 hi-res on
R7 $c01d RDHIRES read hires is off (0) or on (1)
R7 $c01c RDPAGE2 read using page 1(0) or page2(1)
W $c000 80STORE "off" RAMRD/RAMWRT (see above) control
RAM condition.
W $c001 80STORE "on" PAGE2 ($c054/$c055) switches between
page1 main and page1 aux (?)
W $c07e IOUDIS disables IOU access for $c058-$c05F
(so you can use the Dbl-Res swtiches)
W $c07f IOUDIS "off" iou $c058-$c05f off (no dblres switch)
R7 $c07e RDIOUDIS read IOUDIS 0=on 1=off
R/W $c05e DHIRES on (turn on dbl-res) (see IOUDIS)
R/W $c05f DHIRES off (turn dbl-res off) (see IOUDIS)
R7 $c07f RDDHIRES double-res is off(o) or on (1)
W $c00e ALTCHAR "off" use main char set
W $c00f ALTChAR "on" use aux (mouse) char set
R7 $c01e RDALTCHAR using main(0) or aux(1) char set
W $c00c 80COL "off" display 40 columns
W $c00d 80COLl "on" display 80 columns
R7 $c01f RD80COL using 40 (0) or 80 (1) columns
W $c000 80STORE "off" makes PAGE2 switch aux ram
W $c001 80STORE "on" makes PAGE2 switch main ram
R7 $c018 RD80STORE 80STORE is off(0) or on (1)
R7 $C01A RDTEXT text switch is off(0) or on (1)
R/W $c053 MIXED "off" text only or graphics only
R/W $c054 MIXED "on" text/graphics
R7 $c01B RDMIXED mixed flag is off(0) or on (1)
R/W $c057 HIRES "off" display lo-res graphics
R/W $c058 HIRES "on" hires or double-hires
R7 $c01D RDHIRES hires is off (0) or on (1)
Well, that is the most complete list I have seen, hope it helps. I tried to
make the explainations for the switches a little more english than some of the
cryptic discriptions I see in the manuals.
Also, a suggestion for blanking the screen. Don't try and save the time for
each keypress, they may not have a clock. Use a "tick" counter. Have a two
or three byte counter that is incremented each time the interupt is called
(VBL, or whatever). If a key is pressed you reset the counter. If the
counter reaches a certain value (3 minutes would be hex $2A30 using the VBL)
then you execute the blanking function. using the above switches you can tell
what mode the apple was in, and save it (compact the status bits to one byte)
for restoring at the next keypress.
If you are going to try to make the application run with other applications,
it is going to have to intercept the interupts, and applications will change
this value. An install utility could be created, or you could "legally"
install an interupt routine into ProDOS if you can find a "safe" spot in
memory.
Good luck
----------------------------------------------------------------------------
Mark R Hamner "Max Pendragon" pro-lep!max.pendragon
1801 S. Lakeshore #276 Austin Tx 78741
----------------------------------------------------------------------------
_____
UUCP: crash!pro-lep!max.pendragon
ARPA: crash!pro-lep!max.pendragon@nosc.mil
INET: max.pendragon@pro-lep.cts.com