Apple II MockingBoard Mini-manual
(Part 1) - Mockingboard programming
The Sweet Micro Systems MockingBoard comes in four 'flavors':
A. Sound I-- produces music tones and a variety of sound effects (1
B. Speech I-- produces speech and limited sound effects (1 channel
C. Sound II-- 2 x Sound I on a single board (2 channels output)
Speech I-- Sound I + Speech I on a single board (2 channels output)
MockingBoards work on Apple II's with at least 48K RAM. MB can go into
any Slot. Most programs expect it to be in Slot 4; however, it is fairly
common for a program which supports MB to ask you to enter the Slot #.
Most for-MB products use the board for music & sound effects and will
with boards A, C, or D. Products that use MB include Ultima III, Sky Fox,
Wiley Byte', Under Fire, Guitar Master, and Music Star.
MB's 0.5 Watt output(s) can directly drive an 8 Ohm speaker. You can
also run the output(s) to a hi-fi amplifier.
MB "Sound" version boards use the General Instruments AY-3-8910
Programmable Sound Generator IC. The PSG has 3 on-chip tone oscillators
(via channels A, B ,C) and a Noise Generator (NG). So, for example, the
Sound II can play up to 6 notes with 2 noises at once.
MB "Speech" version boards use the Votrax SC-01 Speech Synthesizer
The SC-01 uses 64 phoneme sounds to produce speech. MB software lets you
adjust duration of each phoneme in 4 steps, create "rules" for
sounds, and speak sentences from text in BASIC programs.
All MB versions use the 6522 Versatile Interface IC to handle board
I/O. Except for the Sound I board, there are circuit board points to which
you can add cables to utilize I/O ports not needed for Sound or Speech.
(Part 2) - Sound Programming
The user can set Tone Frequency (12 bits, 4 coarse & 8 fine)* and
Amplitude (4 bits) for each channel individually. A fifth Amplitude bit
you decide if a channel's Level will be "fixed" (use the Level
"variable" (i.e. follow the current Envelope pattern). You can
Frequency (4 bits)* but not level.
*Tone Freq = A2 Clock Freq/ [ (4096 x Coarse) + (16 x Fine) ]
Noise Freq = A2 Clock Freq/ (16 x NG value)
The Envelope of the combined outputs of enabled sources can be
controlled for Period (16 bits, 8 coarse & 8 fine)** and, roughly,
for Shape (4 bits).
**Env Freq = A2 Clock Freq/ [ (65536 x Coarse) + (256 x Fine) ]
The registers of the PSG are described briefly below:
Reg. Function & Bit(s) used
00 A Freq. fine (0-7)
01 A Freq. coarse (0-3)
02 B Freq. fine (0-7)
03 B Freq. coarse (0-3)
04 C Freq. fine (0-7)
05 C Freq. coarse (0-3)
06 NG Freq. (0-4)
07 Enable =0/ Disable =1
NG on A (5) on B (4) on C (3)
Tone on A (2) on B (1) on C (0)
Ex: Writing $F0 to Reg 07 plays tones A, B, C plus noise on C
08 A Level (0-3) and
Envelope Control (4): 1 = Use Env; 0 = Use Level value
09 B Level (0-3) and ...
0A C Level (0-3) and ...
0B Envelope Period Fine (0-7)
0C Envelope Period Coarse (0-7)
0D Envelope Shape (four bits)
Continue (3) 0= do 1 cycle and set Level to zero
Attack (2) 1= count up 0= count down
Alternate (1) 1= reverse count direction each cycle
Hold (0) 1= do 1 cycle and hold count
To program the MB you write to the board's 6522 I/O chip(s). All
addresses reference here are for a MB Sound II (2 Output channels) in Slot
$C400 ORB1 function to perform, OUT 1
$C480 ORB2 function to perform, OUT 2
$C401 ORA1 data, OUT 1
$C481 ORA2 data, OUT 2
$C402 DDRB1 data direction, OUT 1
$C482 DDRB2 data direction, OUT 2
$C403 DDRA1 data direction, OUT 1
$C483 DDRA2 data direction, OUT 2
Before sending music, etc. data to the MB you must Initialize the board's
I/O. To Initialize the 6522's: Store $FF at $C402 and the other three
DDRxx addresses. This needs to be done by your program just once.
Your program gets access to a PSG via the 6522 by using a few basic
Function codes which set the PSG's I/O control lines:
Set Inactive = $04 Set PSG Reg# = $07 Write Data = $06 Reset = $00
To Write to a PSG register: Tell the PSG which Register you wish to access
(i.e. Set the "current register" #) and Write the data. This is
do with subroutines to handle the basic Functions.
Example Subroutines (for Output Channel 1):
Set Reg # 1000: A9 07 8D 00 C4 A9 04 8D 00 C4 60
Write Data 100B: A9 06 8D 00 C4 A9 04 8D 00 C4 60
Notice that each Function sub ends by setting the PSG control lines to
Similarly, to do a Reset (set all PSG regs to zero) ...
Reset 1016: A9 00 8D 00 C4 A9 04 8D 00 C4 60
To put the value $55 in PSG Register 02 (Channel B Freq. fine) ....
1080: A9 02 put Reg# in A
1082: 8D 01 C4 store A at the Data address ORA1
1085: 20 00 10 JSR to Set Reg# (sets "current register" to
1088: A9 55 put the value $55 in A
108A: 8D 01 C4 store A at the Data address ORA1
108D: 20 0B 10 JSR to Write Data ($55 goes into PSG Register 2)
1090: 60 Exit from subroutine