68000 and Memory
BAM
-
The-
K250 has 128 Kbytes
of
memory. The memory is
allocated for the system's use and for sounds.
PROM - The software that controls the K250 is built into PROM.
There are 8 system PROMs
on
the
CPU
board. Two of these are
replaced when the Diagnostic PROMs are used. Each
PROM
is
labeled with a sticker that indicates its location
in
the bank of
PROM, and a checksum value. Every version of the software
will have unique checksums associated with it.
Battery-Backed
Memory
- The CPU board contains a battery
which provides power to retain memory after power down.
This Battery-Backed memory saves keyboard setups and other
user information.
1/0 Ports
MIDI - The MIDI port is a 68A50 serial port.
MIDI
IN
- This is a 31.2K
baud,S
milliamp serial input.
MIDI THRU - This is a 31.2K
baud,S
milliamp serial output.
MIDI OUT - This is a 31.2K
baud,S
milliamp serial output, the
same as
MIDI
In
buffered, conforms to MIDI specifications.
Computer
Port - This port is for attaching a personal computer
to the
K250. The K250 Personal Computer I/O Port currently
uses the Apple Macintosh's serial signalling convention.
Trigger
In - The Trigger
In
is a TTL-compatible input used for
starting a sequence from
an
external device. The sequence
triggers on the positive edge of the
supplied pulse. Miniml,lm
pulse
width is 1 microsecond. The input impedance is greater
than
10k ohms. The trigger level is 2 volts. This I/O port
takes a
1/4 inch phone jack.
Kurzwell
250
Service Manual, Chapter 3
3 - 1 1
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