My crap trig mnemonics

I liked to remember my trig for programming like this:

"shiny cossacks"

x goes with cosine "cos x" -> "cossacks"

y goes with sin "sin y" -> "shiny"


and that made it easy to go to:

x = cos theta

y = sin theta

The Day After Tomorrow

Somehow I missed "The Day After Tommorow" movie when it came out and just watched it now.


I think my head is going to explode from all of this cognitive dissonance. Global warming causes a global ice age... oh my goodness.

I would be embarrassed to have my name listed in the credits as the "Scientific Consultant" when the movie ignores basic physics and logic. I'd call it the "unscientific" consultant.

Sharknado could use an "unscientific" consultant.

It makes for good spectacle, but it doesn't make any sense. Kinda like a lot that's going on in the world today.

Batman's Big Trak

I never knew that Batman had a big trak...(sorry that's Bat Machine)

http://www.toynerd.com/index.php/2010/06/14/how-to-control-the-dark-knight/

Power went out the other day

A couple of days ago the power went out for about 8 hours. It really makes you think about how much we rely on electricity for everything modern.

That really stops you dead in your tracks, sitting in a dark house. Good thing I had some flashlights handy.


I used to have UPS uninterruptible power supplies, but the batteries kept dying after a year or two so I got annoyed and didn't replace them. My desktops didn't make it through the outage, but my laptop (with its own battery) survived unscathed.

First world problems...

Danmere Backer - videotape backup

Years ago, I had a Danmere Backer that was sold by H45 technology. It was a device that attached to the parallel port (there was an ISA card version) and allowed you to save data to videotape by generating NTSC or PAL signals. A good idea in theory, but it had all of the problems that the old audio cassette tape had. For example, with cassette tape, random access to specific files was difficult.

The particular unit I had wouldn't generate "clean" NTSC video and would vertically roll the TV.

I think I only used it once. Recordable CD technology was faster, more easily verifiable, random access and less hassle. Especially when cds jumped from recording at 2x to 48x.


Still, it was a clever idea. It reminds me of Atari 2600 video, with all of the blocky scanlines.

There's an interesting webpage about linux drivers for the backer with screenshots.

http://linbacker.sourceforge.net/screenshots.html


I wonder if it would be possible to generate video signals from an old Amiga 500 that would allow data transfer with a backer.

Theoretically a 320x200 black and white screen could transfer 8k of data per video frame * 60fps = 480KB/sec.


This reminds me of the cauzin softstrip technology with data transfer over paper.


http://cauzin.com/

Or even data transfer over audio like Sofcast. There's an interesting article from PC Mag May 28, 1985.

https://www.google.com/search?q=software+takes+to+the+air+sofcast

Interesting ideas that never caught on.

Vizio M320SL

I got a TV the other day, a Vizio M320SL. It's not bad. I was trying to see how it works as a monitor and it works pretty well, except that it has that property where the brightness varies by the viewer's angle. So if you sit right in the very middle about arm's length, the brightness will vary and the edges of the monitor will look dark. It's kind of a weird effect.

Also it won't come out of standby. I figured out that if I turn the TV on, wait until it'll display "HDMI" on the on screen display, then move my mouse to wake up my ubuntu system out of standby, the computer will recognize that the monitor's there. Otherwise, I have to bring up the display settings to "reenable" the monitor.

Interestingly, the monitor has an owner's manual built-in. That's pretty cool.


I wanted to test it and found these neat online tools to calibrate your monitor.

http://www.makeuseof.com/tag/5-online-tools-calibrate-monitor/

My particular favorite of the group is http://www.lagom.nl/lcd-test/

This would have been so great back in the day

The Vampire 2 is so cool. 226 times an amiga 600.

http://www.kipper2k.com/video/x16.jpg


http://www.kipper2k.com/

Figuring out what etmm=0c and eom=b0 mean

Sometimes windows just disappear offscreen - bring 'em back

If you have a bunch of windows open and you do the multimonitor thing, odds are that sometimes a window just might materialize off the visible screen when you change resolution or enable and disable monitors.

I had some windows that were fine, but after disabling some monitors (2 out of 4) the systems display dialog was offscreen and couldn't be seen.

I could use the ubuntu sidebar to select the window but it wouldn't bring it back.

Perusing all of the shortcuts that come up when you hold down the windows key, one caught my eye: Accessibility menu with Alt+Space.

Selecting the window, then typing alt+space and then choosing move and using the arrow keys, I was able to bring it back on screen.

Yay!

Making SDL allow the screensaver with the debugger

I've been leaving the mame debugger open and my computer hasn't been activating the screensaver under ubuntu.

A little searching and all I have to do is to

export SDL_VIDEO_ALLOW_SCREENSAVER=1

from the command line.


https://wiki.libsdl.org/FAQUsingSDL

Changing the buzzer tone

Reading the upd7810 manual says that the upcounter (ECNT) is incremented every 12 cycles of the phi-12 clock (phi-12 is clock divided by 12) (1 microsecond when operating at 12 Mhz). But it looks like the ap2000 runs at 14.7 mhz.

static MACHINE_CONFIG_FRAGMENT( epson_lx810l )
/* basic machine hardware */
MCFG_CPU_ADD("maincpu", UPD7810, XTAL_14_7456MHz)

So if I want to generate a 1000hz tone, I'll have to fudge the delay a little bit.

The half cycle is 1000us/2=500us and we'll multiply that by (14.7/12) to make 500*(14.75/12) and we get around 615 which is 0x267.

One cycle should take (1/14.7e6*12)*615*2=0.00100408163 which is about right for 1000hz.


My debugger line looks like:

eom=b0;etm1=267;etmm=0c;gt 15


I like the gt 15 (gtime) as it won't drive you totally insane with the beeping.

eom=b0;etm1=4ce;etmm=0c;gt 15

for a bit lower tone (doubling the timer value)


I was actually trying to mimic the apple ii's beep tone, and this sounds similar with etm1=220 being pretty close

etm1=220;eom=b0;etmm=0c;gt 20

Trying to figure out how the buzzer works

I wondered how the buzzer works, and I found some code that looks relevant.

The buzzer is on PC7 which is the C01 counter output.

If I send a $07 bel character the ap2000 will beep, executing the routine at $1057.

debugger commands to make my trace log:

WP 8000,1F00,w,1,{tracelog " WRITE addr=%x data=%x \n", wpaddr,wpdata;g}
WP 8000,1F00,r,1,{tracelog " READ addr=%x data=%x \n", wpaddr,wpdata;g}
WP FF00,100,w,1,{tracelog " WRITE addr=%x data=%x \n", wpaddr,wpdata;g}
WP FF00,100,r,1,{tracelog " READ addr=%x data=%x \n", wpaddr,wpdata;g}

WP 0000,8000,r,1,{tracelog " READROM addr=%x data=%x \n", wpaddr,wpdata;g}

trace TRACEbeep.TXT,0,{tracelog "A=%02X EA=%04X HL=%04X DE=%04X BC=%04X SKIP=%1X  |  ",a,ea,hl,de,bc,(psw&0x20)!=0}




    223 A=00 EA=9000 HL=13DA DE=8013 BC=FB00 SKIP=0  |  135C: ACI     H,$00
    224 A=00 EA=9000 HL=13DA DE=8013 BC=FB00 SKIP=0  |  135F: LDEAX   (HL)
    225  READROM addr=13DA data=57 
    226  READROM addr=13DB data=10 
    227 A=00 EA=1057 HL=13DA DE=8013 BC=FB00 SKIP=0  |  1361: JEA     
    228 A=00 EA=1057 HL=13DA DE=8013 BC=FB00 SKIP=0  |  1057: LXI     HL,$0000
    229 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  105A: ORIW    VV:10,$04
    230  READ addr=9810 data=0 
    231  WRITE addr=9810 data=4 
    232 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  105D: PUSH    HL
    233 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  105E: CALL    $7BB1
    234 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  7BB1: ONIW    VV:0F,$C0
    235  READ addr=980F data=0 
    236 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  7BB4: OFFIW   VV:01,$30
    237  READ addr=9801 data=8 
    238 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=1  |  7BB7: JR      $7BA9
    239 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  7BB8: RET     
    240 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  1061: POP     HL
    241 A=00 EA=1057 HL=0000 DE=8013 BC=FB00 SKIP=0  |  1062: DMOV    EA,HL
    242 A=00 EA=0000 HL=0000 DE=8013 BC=FB00 SKIP=0  |  1063: DMOV    BC,EA
    243 A=00 EA=0000 HL=0000 DE=8013 BC=0000 SKIP=0  |  1064: PUSH    BC
    244 A=00 EA=0000 HL=0000 DE=8013 BC=0000 SKIP=0  |  1065: PUSH    BC
    245 A=00 EA=0000 HL=0000 DE=8013 BC=0000 SKIP=0  |  1066: CALL    $1084
    246 A=00 EA=0000 HL=0000 DE=8013 BC=0000 SKIP=0  |  1084: MVI     A,$00
    247 A=00 EA=0000 HL=0000 DE=8013 BC=0000 SKIP=0  |  1086: MOV     ETMM,A
    248 A=00 EA=0000 HL=0000 DE=8013 BC=0000 SKIP=0  |  1088: MVI     EOM,$B0
    249 A=00 EA=0000 HL=0000 DE=8013 BC=0000 SKIP=0  |  108B: LXI     EA,$008C
    250 A=00 EA=008C HL=0000 DE=8013 BC=0000 SKIP=0  |  108E: DMOV    ETM1,EA
    251 A=00 EA=008C HL=0000 DE=8013 BC=0000 SKIP=0  |  1090: MVI     A,$0C
    252 A=0C EA=008C HL=0000 DE=8013 BC=0000 SKIP=0  |  1092: MOV     ETMM,A
    253 A=0C EA=008C HL=0000 DE=8013 BC=0000 SKIP=0  |  1094: MVI     C,$3C
    254 A=0C EA=008C HL=0000 DE=8013 BC=003C SKIP=0  |  1096: CALT    ($0080)
  
...

    341 
    342    (loops for 15827 instructions)
    343 
    344 A=00 EA=0001 HL=0000 DE=8013 BC=FFFF SKIP=0  |  0030: JR      $003D
    345 A=00 EA=0001 HL=0000 DE=8013 BC=FFFF SKIP=0  |  003D: POP     BC
    346 A=00 EA=0001 HL=0000 DE=8013 BC=003C SKIP=0  |  003E: POP     VA
    347 A=0C EA=0001 HL=0000 DE=8013 BC=003C SKIP=0  |  003F: POP     EA
    348 A=0C EA=008C HL=0000 DE=8013 BC=003C SKIP=0  |  0040: RET     
    349 A=0C EA=008C HL=0000 DE=8013 BC=003C SKIP=0  |  1097: MVI     EOM,$99
    350 A=0C EA=008C HL=0000 DE=8013 BC=003C SKIP=0  |  109A: RET  

the action looks to happen with putting EOM=B0, ETM1=8C AND ETMM=0C

to shut it off it puts EOM=99

so for kicks if you run the ap2000 in the debugger and the ap2000 is waiting for input you can make it beep with the following debugger command line:

etm1=8c;eom=b0;etmm=0c

and to shut it off

eom=99

before you do this, you may want to turn your speakers down, it's really a terrible sound. heh heh

Interrupt Vectors on ap2000

The ap2000 has its code in rom, so it uses a jump to redirect to a location in ram where it's put another JMP.

00000000: 54 E0 00           JMP     $00E0
00000003: 00                 NOP     

NMI interrupt is at 0004

00000004: 54 2A 0C           JMP     $0C2A
00000007: 00                 NOP     

INTT0 and INTT1 interrupts are at 0008

00000008: 11                 EXX           
00000009: 10                 EXA     
0000000A: 54 17 98           JMP     $9817
0000000D: 00                 NOP     
0000000E: 00                 NOP     
0000000F: 00                 NOP     

INT1 AND INT2 are at 0010

00000010: 00                 NOP     
00000011: 00                 NOP     
00000012: 00                 NOP     
00000013: 00                 NOP     
00000014: 00                 NOP     
00000015: 00                 NOP     
00000016: 00                 NOP     
00000017: 00                 NOP     

INTE0 and INTE1 are at 0018

00000018: 11                 EXX     
00000019: 10                 EXA     
0000001A: 54 1A 98           JMP     $981A
0000001D: 00                 NOP     
0000001E: 00                 NOP     
0000001F: 00                 NOP     

INTEIN and INTAD are at 0020

00000020: 00                 NOP     
00000021: 00                 NOP     
00000022: 00                 NOP     
00000023: 00                 NOP     
00000024: 00                 NOP     
00000025: 00                 NOP     
00000026: 00                 NOP     
00000027: 00                 NOP     

INTSR and INTST are at 0028

00000028: 54 CE 20           JMP     $20CE

The most interesting ones for me to study right now are the JMP to $9817 and $981A.


at $016A we put 54 in 9817 with MOV ($9817),A to put the JMP opcode in place

0000016A: 69 54              MVI     A,$54
0000016C: 70 79 17 98        MOV     ($9817),A
00000170: 70 79 1A 98        MOV     ($981A),A
00000174: 40 F7 0B           CALL    $0BF7

and the code at 0BF7 puts 0C0F into the address at $9818 to fix the address to make it JMP $0C0F.

00000BF7: 64 9D E0           ORI     TMM,$E0
00000BFA: 48 42              SKIT    FT1
00000BFC: 00                 NOP     
00000BFD: 69 26              MVI     A,$26
00000BFF: 4D DB              MOV     TM1,A
00000C01: 34 0F 0C           LXI     HL,$0C0F
00000C04: 70 3E 18 98        SHLD    $9818
00000C08: 64 8D 3F           ANI     TMM,$3F
00000C0B: 64 0F FB           ANI     MKL,$FB
00000C0E: B8                 RET     
00000C0F: 40 16 0C           CALL    $0C16
00000C12: 11                 EXX     
00000C13: 10                 EXA     
00000C14: AA                 EI      
00000C15: 62                 RETI    


There seem to be only a few routines for these two interrupt vectors.

Using my good friend grep with -A (after) and -B (before) gives us

~/Downloads/mame$ grep -A 2 -B 2 '9818' ap2k_disasm
00000BFF: 4D DB              MOV     TM1,A
00000C01: 34 0F 0C           LXI     HL,$0C0F
00000C04: 70 3E 18 98        SHLD    $9818
00000C08: 64 8D 3F           ANI     TMM,$3F
00000C0B: 64 0F FB           ANI     MKL,$FB
--
00001E52: 70 3E 1B 98        SHLD    $981B
00001E56: 34 04 7A           LXI     HL,$7A04
00001E59: 70 3E 18 98        SHLD    $9818
00001E5D: B8                 RET     
00001E5E: 55 10 02           OFFIW   VV:10,$02
--
00001EA7: 70 3E 1B 98        SHLD    $981B
00001EAB: 34 5A 7A           LXI     HL,$7A5A
00001EAE: 70 3E 18 98        SHLD    $9818
00001EB2: CE                 JR      $1EC1
00001EB3: 34 E3 1D           LXI     HL,$1DE3
00001EB6: 70 3E 1B 98        SHLD    $981B
00001EBA: 34 5A 7A           LXI     HL,$7A5A
00001EBD: 70 3E 18 98        SHLD    $9818
00001EC1: 69 0C              MVI     A,$0C
00001EC3: 4D CC              MOV     ETMM,A
--
000079E9: 64 9D E0           ORI     TMM,$E0
000079EC: 34 04 7A           LXI     HL,$7A04
000079EF: 70 3E 18 98        SHLD    $9818
000079F3: 15 0F 01           ORIW    VV:0F,$01
000079F6: 69 E6              MVI     A,$E6
--
00007A84: 99                 CALT    ($00B2)
00007A85: 34 04 7A           LXI     HL,$7A04
00007A88: 70 3E 18 98        SHLD    $9818
00007A8C: 55 00 80           OFFIW   VV:00,$80
00007A8F: 5E 00              BIT     6,VV:00

~/Downloads/mame$ grep -A 2 -B 2 '981B' ap2k_disasm
00001E4C: 64 0F DF           ANI     MKL,$DF
00001E4F: 34 78 1E           LXI     HL,$1E78
00001E52: 70 3E 1B 98        SHLD    $981B
00001E56: 34 04 7A           LXI     HL,$7A04
00001E59: 70 3E 18 98        SHLD    $9818
--
00001EA3: CF                 JR      $1EB3
00001EA4: 34 85 1D           LXI     HL,$1D85
00001EA7: 70 3E 1B 98        SHLD    $981B
00001EAB: 34 5A 7A           LXI     HL,$7A5A
00001EAE: 70 3E 18 98        SHLD    $9818
00001EB2: CE                 JR      $1EC1
00001EB3: 34 E3 1D           LXI     HL,$1DE3
00001EB6: 70 3E 1B 98        SHLD    $981B
00001EBA: 34 5A 7A           LXI     HL,$7A5A
00001EBD: 70 3E 18 98        SHLD    $9818
--
0000319F: 48 D2              DMOV    ETM0,EA
000031A1: 34 F5 31           LXI     HL,$31F5
000031A4: 70 3E 1B 98        SHLD    $981B
000031A8: 48 45              SKIT    FE0
000031AA: 00                 NOP     

Now to figure out what these interrupts do 8-)