Kurzweil K150 - PROGRAMMERS MODEL REV A Hardware Manual page 3

The primary program EPROM is 16 bits wide and consists of one or two pairs of 27256 EPROMS. U55 and U57 chips must
be present since they are addressed beginning at $000000 and contain the startup and interrupt vectors. U54 and U56 are
optional and may be used if the program becomes larger than 64K bytes. Of course sound data may also be present in either
pair of EPROMs if desired with the advantage of zero wait state data access.
When using an EPROM programmer to prepare software for the K150FS, it is useful to know that the address and data bit
assignments are the same as the industry standard given in databooks. AO is the least significant address bit and A14 is the
most significant. Likewise, DO is the least significant data bit and D7 is the most significant. Data is stored in the EPROM
in positive true polarity.
The primary scratch RAM is also 16 bits wide and consists of a pair of 6264 static RAMs for a total of 16K. This RAM is
non volatile. It is intended for rapid access uses such as the 68000 stack, expanded parameter lists, and the like but could
also be used for RAM-resident sounds with the advantage of zero wait state access.
The parameter RAM, sound RAM, and sound ROM are each 8 bits wide but still appear to the programmer as if they are 16
bits wide. The 8-to-16 bit conversion hardware adds 5 wait states for a 16-bit access in order to do two 8-bit accesses.
However, if the 68000 instruction is a byte mode instruction, only 2 wait states are added. It is possible to put program code
in these memories but operation would be substantially slowed due to the extra wait states. The Sound EPROM sockets will
accept either 27256 EPROMs for 32K bytes each or 27512 EPROMs for 64K bytes each. They can also accept 1 megabit
mask ROMs (128K bytes each) but not 1 megabit EPROMs (the latter have 32 pins instead of 28).
MC6840 TIMER
The MC6840 contains 3 independent counter timers. Timer #1 is completely general purpose and has nothing connected to
its clock input or timer output. Timer #2 can be used by software to count sample periods (51.2uS each) of the sound
generator. Its clock input is connected to a square wave with a 51.2uS period. Timer #3 must be programmed to output a
500KHz square wave which is used as the baud rate input of the MC6850 MIDI UART described below. Nothing is
connected to timer #3's clock input but the system clock (Enable frequency) is 1.0MHz. The gate inputs to all three timers
are wired to permanent ones.
The 6840 register addresses are as follows:
$024001 (write)
$024003 (read)
$024003 (write)
$024005 (read)
$024005 (write)
$024007 (read)
$024007 (write)
$024009 (read)
$024009 (write)
$02400B (read)
$02400B (write)
$02400D (read)
$02400D (write)
$02400F (read)
$02400F (write)
Programming details for the 6840 can be found attached to the end of this document.
MC6850 MIDI UART
A Motorola 6850 Serial Interface Adapter is used for MIDI I/O. Only the serial input and serial output are used; the modem
control outputs are not used and the modem control inputs are hardwired such that full operation of the transmitter and
receiver are permitted. The baud rate is taken from timer 3 of the 6840 described above. For the standard 31.25 KBaud
MIDI rate, 16X clock is selected in the 6850 and timer 3 is set for 2uS = 500KHz.
K150FS Programmer's Model
Control Register #1 and #3
Status Register
Control Register #2
Timer #1 counter
Write MSB Buffer Register
Read LSB Buffer Register
Timer #1 latches
Timer #2 counter
Write MSB Buffer Register
Read LSB Buffer Register
Timer #2 latches
Timer #3 counter
Write MSB Buffer Register
Read LSB Buffer Register
Timer #3 latches
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Rev. A 26-APR-88