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APPENDIX
D: Specifications
Processors
Video
Display
The
Radio
Shack TRS-80 15-Meg
Built-in
Hard
Disk
System
is
a
disk-based
computer system
with
two major
parts:
•
A
display
console
with
a
Built-in
Hard
Disk
System and
a
built-in
double-sided, double-density floppy
disk
drive.
•
A
detached keyboard which can be
positioned
for
your
comfort
and
efficiency
The
operating
system
software
is
loaded from a system
diskette
in
Drive
or
Drive
4 by a
built-in
ROM
"bootstrap"
program.
Input/Output
Processor
System
•
Z80-A based
with
64K
bytes
of
random
access
memory
• Independent
bus can support
all
the
standard
system boards
•
Emulation
mode
lets
you execute
programs
previously
developed
for
the
TRS-80 Model
II
without
changing them
first.
Computational Processor
System
• 68000 based
with either
128K
or
256K
(384K
or
51
2K
bytes
on
a
Model
16B)
of
RAM
• Independent
bus can
support
multiple
bus masters
The two
processors share
the
computing
load
from
the application
programs
(the
Z80-A based
processor performs
input/output
tasks
while the
68000 based
processor performs computational
tasks),
LSI Controller
Chip
Frees
the input/output
(Z80-A based) processor from
much
of
the
overhead
required
to
update and
maintain the video
display.
Four
Modes
• Green/White on black
(normal)
• Black on green/white
(reversed)
• 80
characters
by 24
lines
• 40
characters
by 24
lines
Displayable Characters
•
Full
ASCII
set
• 32
graphics characters
60
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