Radio Shack TRS-80 User manual
·-
•
erv1ce
TRS-BO
®
Color
Computer
2
Catalog
Number
26-3026/7
CUSTOM MANUFACTURED
IN
U.S.A. BY RADIO SHACK, A DIVISION OF TANDY CORPORATION
-----------TRS-80
®
-----------
TRS-80®
Color
Computer
2
Service
Manual
Copyright~
1983
Tandy
Corporation
All
Rights
Reserved
Reproduction
or
use,
without
express
written
permission
from
Tandy
Corporation,
of
any
portion
of
this
manual
is
prohibited.
While
reasonable
efforts
have
been
taken
in
the
preparation
of
this
manual
to
assure
its
accuracy,
Tandy
Corporation
assumes
no
liability
resulting
from
any
errors
or
omissions
in
this
manual,
or
from
the
use
of
the
information
contained
herein.
----------ltad1elllaell----------
Color
Computer
2
TRS-BO
®
Service
Manual
TABLE
OF
CONTENTS
1/
General
1.1
1.
2
1.
3
Introduction
•......
System
Description
......
.
Memory
Map .
.............
.
2/
Specifications
2.1
2.2
2.3
Physical..
Power
.....
Technical.
3/
Disassembly/Assembly
3.1
3.2
3.3
Disassembly
.........
.
Assembly
.
....•...........
64K
Upgrade
Instructions.
4/
Theory
Of
Operation
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
4.14
4.15
MC6809E
CPU
...
Reset
Circuit
..
Memory
.......
.
Video
Generation
Circuitry.
Artifacting
............
.
PIAs
....•
ROM •
•••••
Keyboard
Interface
..
DAC
Circuitry
.....
.
SALT
Circuitry
.•........•.••.
Cassette
Tape
Format
Information
..
RS232
Connector
(J3)
Cartridge
Connector
(J6).
Power
Transformer
.........
.
Joysticks
......
.
4.16
TV
Switch
Box
.•.
Schematic
8000191,
Color
Computer.
Component
Layout
1700235,
Main
Logic
Board
8857636.
Circuit
Trace,
PCB
8857636,
Component
Side
.......
.
Circuit
Trace,
PCB
8857636,
Solder
Side
..
Parts
List,
PCB
8857636
................
. .•..
1
1
6
13
13
13
15
16
18
19
26
27
31
34
36
39
39
41
44
48
49
51
55
55
56
57
61
63
65
67
ltadle
lhaell----------
i
Color
Computer
2
-----------TRS-BO
®
Service
Manual
5/
Troubleshooting
5
.1
Introduction
.
......................................
.
5.
2
Video
Problems
..
...................................
.
5.2.1
No
Display
.......................................
.
5 . 2 . 2 No
Sync
..........•..................•..•.......•..
5.2.3
5.2.4
5.2.5
5.2.6
5.2.7
"Garbage"
on
Screen
..............................
.
Clear
Screen,
No
Signon
..................•••......
No
Color
.
........................................
.
Wrong
Colors
.
....................................
.
No
Artifacting
Or
Improper
Artifacting
...........
.
5.
3
Keyboard
.
..........................................
.
5.3.1
No
Keyboard
Entry
..............................•..
5.3.2
Some
Keys
Inoperative~
...........................
.
5.
3.
3
Wrong
Character
for
Key
Pressed
...............•...
5.
4
Processing
Problems
.
...............................
.
5.4.l
General
..........................................
.
5.4.2
5.5
5.5.l
5.5.2
5.5.3
5.6
5.6.1
5.6.2
5.7
5.8
5.9
5.10
Symptoms
.........................................
.
Cassette
Problems
.
.................................
.
Motor
Control
Problems
.........•....•....•........
Write
Problems
..
.................................
.
Read
Problems
..
..................................
.
RS
232
Problems
.
....................................
.
Output
Missing
or
Incorrect
......................
.
Input
Problems
.
..................................
.
Sound
Problems
.
....................................
.
Joystick
Problems
..................................
.
Cartridge
Problems
.
................................
.
Power
Supply
.
......................................
.
6/
Exploded
View/Parts
List
71
72
72
73
73
74
74
75
75
76
76
76
76
77
77
77
80
80
80
81
81
81
82
82
82
83
83
Exploded
View
.......................................
98
Parts
List
..........................................
99
Appendices
MC6809E
Data
Sheet
(Motorola
DS9846-Rl)
SN74LS783
Data
Sheet
(Motorola
ADI-595)
MC6847
Data
Sheet
(Motorola
DS9823)
MC6821
Data
Sheet
(Motorola
DS9435-R2)
MC6822
Data
Sheet
(Motorola
ADI-938)
----------
llad1elhaell----------
ii
,..
.·
Color
Computer
2
Service
Manual
-----------TRS-BO
®
-----------
Fig.
1-1
1-2
1-3
3-1
3-2
3-3
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
Description
Color
Computer
2
Color
Computer
2
Color
Computer
2
Color
Computer
2
Color
Computer
2
Color
Computer
2
Color
Computer
2
LIST
OF
FIGURES
Page
No.
Installation....................
2
Block
Diagram...................
4
Memory
Map
(Page
1).
. . . . . . . . . . . . 6
Memory
Map
(Page
2).............
7
Memory
Map
(Page
3).............
8
Memory
Map
(Page
4)
.............
10
Memory
Map
C
Page
5).
. . . . . . . . . . . .
11
Shield
Clip
Location
.............................
16
Power
Cord
Strain
Relief
.........................
17
64K
Upgrade.
. . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . .
18
MC6809E
Programming
Model
........................
20
MC6809E
Pin
Assignments
..•.......................
23
MC6809E
Read/Write
Timing
at
0.895
MHz
...........
25
MC6883
Reset
Circuitry
...........................
26
DRAM
Block
Diagram
...............................
28
DRAM
Timing......................................
29
Color
Computer
2
Address
Decoding
................
31
Color
Computer
2
Artifacting
Circuitry
...........
35
PIA
Block
Diagram................................
37
Color
Computer
2
Keyboard
Array
..................
40
DAC
Block
Diagram................................
42
SALT
Block
Diagram
...............................
45
Color
Computer
2
Power
Supply
....................
46
I/O
Circuitry....................................
47
RS-232C
Connector
Pin-Out
........•....•..........
49
Joystick
Schematic...............................
55
Antenna
Switch
Box
Schematic
.....................
56
Normal
Power
Supply.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Defective
Power
Supply
...........................
88
High
Frequency
Component
of
+5V
Source
...........
89
E
and
Q
Clocks.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
90
VDG
Clock
and
Modulator
Clock
....................
90
Y
and
Phase
B...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
91
Phase
Band
Phase
A
Relationships,
Green
Screen
..
92
Phase
Band
Phase
A
Relationships,
Blue
Screen
...
92
Phase
Band
Phase
A
Relationships,
Red
Screen
....
92
Artifacting
Signals..............................
93
Artifacting
Signals..............................
93
Artifacting
Signals..............................
93
Address
Lines
(Typical)
..........................
94
Data
Lines
(Typical)
.............................
94
----------
ltadtelhaell----------
iii
Color
Computer
2
Service
Manual
-----------TRS-80
®
-----------
LIST
OF
FIGURES
(con't)
Fig.
Description
Page
No.
5-15
5-16
5-17
5-18
RAS*
and
CAS*
...................................
.
Data
IN
and
Data
OUT
........••••.................
Sound
and
Cassette
Output
.......................
.
Cassette
Zero
Crossing
Detector
.................
.
95
95
96
96
6-1
Color
Computer
2
Exploded
View
...................
98
LIST
OF
TABLES
1
Line
Printer
variables
...................•.......
51
2
Alternate
Line
Printer
Variable
Values
.......•...
52
3
Cartridge
Connector
Signals......................
53
--------------------ladtelhaell-------------------
iv
Color
Computer
2
-----------TRS-BO
®
1/
General
1.1
Introduction
Service
Manual
The
Color
Computer
2
is
a
refined
version
of
Radio
Shack's
popular
Color
Computer.
It
is
designed
to
provide
the
same
reliable
operation
as
its
predecessor,
but
incorporates
the
latest
in
electronic
technology.
Interconnection
to
a
video
monitor,
printout
device,
or
modem
provides
maximum
versatility
of
the
Color
Computer
2.
Figure
1-1
shows
a
typical
installation
of
the
Color
Computer
2.
Interconnecting
cables
are
noted
which
provide
signal
and
control
transfer
between
the
major
components.
Always
remember
to
remove
all
power
from
the
Color
Computer
2
prior
to
installing
any
peripheral
device
to
prevent
damage
to
the
device
or
the
Color
Computer
2.
The
Color
Computer
2
contains
an
internal
BASIC
program
in
ROM
which
is
accessed
when
the
unit
is
powered
up.
Other
program
modules/cartridges
may
be
inserted
into
the
receptacle
at
the
right
side
of
the
unit.
An
optional
Multipak
Interface
module
allows
up
to
four
program
paks
to
be
installed
at
the
same
time
with
selection
of
the
specific
module
active
at
any
one
time
selected
either
by
software
or
by
a
switch
on
the
Multipak
Interface
module.
Additional
peripheral
devices,
such
as
an
external
disk
drive,
may
be
added
to
the
Color
Computer
2
for
additional
memory
storage
and
retrieval.
All
inputs
to
or
outputs
from
the
Color
Computer
2,
with
the
exception
of
the
program
module/cartridges,
are
contained
on
the
rear
panel
of
the
unit.
These
include
the
joystick
inputs
(right
and
left),
Serial
I/O,
Cass
I/O,
TV
output
connector,
Power
ON/OFF
switch,
and
RESET
switch.
A
recessed
channel
switch
(for
selecting
either
channel
3
or
4
on
the
TV)
is
also
located
on
the
rear
panel
of
the
unit.
1.2
System
Description
The
primary
functions
of
the
Color
Computer
2
are
performed
by
five
40-pin
Large
Scale
Integration
(LSI)
chips
plus
Random
Access
Memory
CRAM)
and
Read
Only
Memory
CROM).
These
five
chips
are
labeled
on
the
Block
Diagram
as
CPU,
SAM,
VDG,
and
two
PIAs.
With
only
these
five
chips
plus
RAM,
ROM,
and
a
power
supply,
the
Color
Computer
2
will
operate
and
provide
a
composite
video
output.
However,
to
allow
communication
with
the
outside
world,
I/O
interfaces
must
be
added.
-----------
ltadtelhaeli----------
- 1 -
Color
c
ornputer
2
COLOR
MONITOR
LEFT JOYSTICK
Figure
1-1.
TRS-BO
®
anual
-
--------~S~e=r~v~i:c:e_~~~~~
RIGHT JOYSTICK
Color
c
ornputer
2
Installat'
ion
ltad1elhaell
----
- 2 -
__
c
_o_
1
_o_
r_ c_o_m_p_u_t_e_r_ 2
____
TRS
-
BO
®
Service
Manual
The
main
component
of
any
computer
system
is
the
Central
Processor
Unit
(CPU,
U23).
It
is
the
function
of
the
CPU
to
provide
or
request
data
and
select
the
proper
address
for
this
data.
In
addition,
the
CPU
is
capable
of
performing
a
limited
set
of
mathematical
and
logical
operations
on
the
data
.
ROM
(Ul2
+
Ul3
in
Extended
Basic)
has
the
function
of
providing
the
CPU
with
a
pre-defined
set
of
instructions.
Without
ROM,
the
CPU
would
run
wild
and
randomly
execute
instructions.
In
normal
operation,
the
CPU
jumps
to
the
start
address
in
ROM
after
the
reset
switch
has
been
pressed
and
then
performs
the
reset
program
to
set
up
all
of
the
progr
a
mmable
devices.
Following
this,
the
BASIC
interpreter
residing
in
ROM
is
in
control
of
the
CPU.
RAM
(Ul4
thru
U21)
provides
storage
for
the
programs
and/or
data
currently
being
executed.
In
the
standard
unit,
these
eight
res
are
16K
x 1 (MCM4517)
but
may
be
upgraded
to
64K x
1
res
(MC6665)
as
an
option
(see
Paragraph
3.3
for
instructions).
In
addition,
this
same
RAM
is
used
to
generate
the
video
display.
Normally,
no
conflict
will
be
observed
because
the
program
wil
l
use
one
portion
of
RAM
and
the
display
will
use
another.
Duri
ng
normal
usage,
the
BASIC
interpreter
located
in
ROM
will
cont
rol
the
execution
of
programs
located
in
RAM.
A
central
component
in
the
Color
Computer
2
is
the
Synchronous
Address
Multiplexer
(SAM,
U22).
This
chip
provides
refresh
and
address
multiplexing
for
the
RAM.
It
also
provides
all
of
the
system
timing
and
device
selection.
The
video
display
generator
(VDG, U8)
provides
virtually
the
entire
video
interface
on
one
chip
and
allows
several
alphanumeric
and
graphic
modes.
The
mode
of
operation
of
the
VDG
is
controlled
by
one
of
two
Peripheral
Interface
Adapters
(PIAs,
U2
and
U7)
used
in
the
Colo
r
Computer
2.
With
this
information
and
RAM
data
,
the
VDG
generates
composite
video
and
color
information
for
the
modulator
circuitry.
----------1tad1elhae
ll
-
---------
- 3 -
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.....
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t'1
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to
t-'
0
()
;io\"'
0
.....
Pl
'°
t'1
Pl
9
U1
POWER
SUPPLY
I
•5V
-
5V
U23
CPU
MC6809E
CONT
SIGN
AOL
ALS
.
-
us
-
BUF
FER -
74LS
244
'------
-
,____
IF
-
:
•
~
' r
CARTRIDGE
CONNECTOR
-
U5
DATA
OUT
-
LATCH
DISPLAY
DATA
74LS
273
~
11
DYNAMIC
RAM
MCM4517
U14
-21
(64K
x
8)
MC6665
~
DEVICE
U22
1---
SELECl
SAM
DYNAMIC
-U10
RAM
CONTROLLER
74LS02
~
74LS138
MC6883
DATA
ADDRESS
' t
'
U12
(U13}
SK
OR
16K
x 8
ROM
MC68A364
TV
t
U9
SOUND
MODULATOR
MC1372
I
VIDEO
r------ --------
I
:
SOUND
ua
I
I
VOG
I
GENERATOR
I
MC6847
I I
U3
I
I
•
..
I r
I
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MC6821
INTERFACE
U1
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.._
RS
232
INTERFACE
f-4--
"'----
-----------
~
j l
U7
U3
PIA
--
JOYSTICK
MC6822
INT
ERFACE
T i i
KEYBOAR
D
-,
I
I
I
_J
oRcoiii'TiloL:
1
----------
JOYSTICKS
(')
0
t-'
0
t'1
(')
0
9
"O
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(1)
t'1
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t'1
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.....
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Color
Computer
2
-----------TRS-BO
®
Service
Manual
The
remaining
circuitry
in
the
Color
Computer
2
is
devoted
to
Input/Output
(I/0)
communication.
The
most
important
part
of
this
circuitry
is
the
keyboard
which
allows
the
operator
to
enter
information.
Other
I/O
circuits
are
provided
to
allow
joystick
inputs,
cassette
input
and
output,
and
RS-232
input
and
output.
1.3
Memory
Map
The
first
page
of
the
Memory
Map
(Figure
1-3)
shows
the
breakdown
of
the
large
blocks
of
memory
in
the
Color
Computer
2.
One
variable
in
this
block
is
the
video
display
which
may
be
located
anywhere
in
the
memory.
BASIC
normally
locates
the
video
display
at
the
hexidecimal
addresses
from
0400
to
05FF.
The
next
two
pages
of
the
Memory
Map
explain
the
addressing
for
the
PIAs.
In
general,
the
even
numbered
memory
locations
are
the
I/O
registers
and
the
odd
numbered
memory
locations
are
the
control
registers.
Bit
two
of
the
control
registers
determines
what
is
addressed
at
the
even
numbered
memory
locations.
If
this
bit
is
set
high
(logic
1),
the
data
I/O
register
is
addressed.
If
it
is
set
low,
the
data
direction
register
is
addressed.
Normally,
the
data
direction
register
is
addressed
only
during
initialization
to
allow
configuration
of
the
data
inputs
and
outputs.
By
clearing
bit
2
and
writing
to
the
even
numbered
memory
location
one
address
below,
each
bit
of
the
PIA
may
be
set
as
an
input
or
an
output.
A 1
in
the
data
direction
register
sets
the
bit
as
an
output
and
a 0
sets
the
bit
as
an
input.
----------1tad1elhaell----------
- 5 -
Color
Computer
2
-----------TRS-80
®
FF00
C000
A000
4000
2000
1000
0000
HEX
ADDRESS
CARTRIDGE
ROM
t
":;~
tEXPANSION
I
ROM
COLOR COMPUTER
USAGE
16K RAM
Service
Manual
64K
RAM
(ALTERNATE
OPERATING MODE)
0600
ANORMAL
VIDEO
0400 I
DISPLAY
Figure
1-3.
Color
Computer
Memory Map
(page
1)
----------1tad1e/haell----------
- 6 -
Color
Computer
2
Service
Manual
-----------TRS-BO
®
-----------
FF00 -FF03 PIA U7
BIT 0 =
KEYBOARD
ROW
1
and
right joystick switch
BIT
1
=KEYBOARD
ROW
2
and
left
joystick switch
BIT
2
=KEYBOARD
ROW
3
FF00
BIT
3
=KEYBOARD
ROW
4
BIT
4
=KEYBOARD
ROW
5
BIT
5
=KEYBOARD
ROW
6
BIT
6
=KEYBOARD
ROW
7
BIT
7
=JOYSTICK
COMPARISON INPUT
Control
of
the Horizontal
0=1RO*to
CPU
Disabled
1=1RQ*
to
CPU
Enabled
sync clock (63.5 microseconds) 0=Flag
set
on
the falling
edge
of
HS
Interrupt Input
BIT
2
=Normally
1:
BIT3=SEL1
:
1=Flag
set
on the rising
edge
of
HS
0=Changes
FF00
to
the data direction register
LSB
of
the
two
analog
MUX
select lines
FF01
BIT
4 = 1 Always
BIT
5 = 1 Always
FF02
FF03
BIT
6 Not
Used
BIT
7 = Horizontal sync interrupt flag
BIT
0=
KEYBOARD
COLUMN 1
BIT
1=
KEYBOARD
COLUMN 2
BIT
2=
KEYBOARD
COLUMN 3
BIT
3=
KEYBOARD
COLUMN 4
BIT
4=
KEYBOARD
COLUMN 5
BIT
5=
KEYBOARD
COLUMN 6
BIT 6=
KEYBOARD
COLUMN
7/RAM
SIZE OUTPUT
BIT
7=
KEYBOARD
COLUMN 8
BIT
0 l .
Control
of
the field sync clock
BIT
1 16.667
Ms
Interrupt Input l
0=1
RO*
to
CPU
Disabled
1=1RQ* to
CPU
Enabled
0=
sets
flag on falling
edge
FS
1=
sets
flag on rising
edge
FS
BIT 2 =
NORMALLY
1:
BIT3=SEL2
:
0=
changes
FF02
to
the data direction register
MSB
of
the
two
analog
MUX
select lines
BIT
4 = 1 Always
BIT
5 = 1 Always
BIT 6
Not
Used
BIT
7 = Field sync interrupt flag
Figure
1-3.
Color
Computer
Memory
Map
(page
2)
-----------
llad1elhaell----------
- 7 -
Color
Computer
2
-----------TRS-BO
®
FF20 -FF23
FF20
PIA U2
BIT
0 =CASSETTE
DATA
INPUT
BIT
1 =
RS
-232
DATA
OUTPUT
BIT
2 = 6
BIT
D/A
LSB
BIT3=6BITD
/A
BIT
4 = 6
BIT
D/A
BIT
5 = 6
BIT
DIA
BIT6=6BITD
/A
BIT 7 = 6
BIT
D/A
MSB
BIT
0 l
Control
of
the
CD
BIT
1 RS-232 status Input
Service
Manual
l
0 = FI
RO
*
to
CPU
Disabled
1 =
FIRO*to
CPU
Enabled
0
=set
flag
on
falling
edge
CD
1 =
set
flag on rising
edge
CD
BIT
2
=Norm
ally 1: 0 =changes
FF20to
the data direction register
FF21
FF22
FF23
BIT
3 =
Cassette
Motor
Control : 0
=OFF
1
=ON
BIT4
= 1 Always
BIT
5 = 1 Always
BIT
6 Not
Used
BIT 7 =
CD
Interrupt
Flag
BIT
0 = RS-232
DATA
INPUT
BIT
1 = SINGLE
BIT
SOUND OUTPUT
BIT
2 = RAM SIZE INPUT
BIT
3 = VDG CONTROL OUTPUT
BIT
4 = VDG CONTROL OUTPUT
BIT
5 = VDG CONTROL OUTPUT
BIT
6 = VDG CONTROL OUTPUT
BIT
7 = VDG CONTROL OUTPUT
BIT
01
Control
of
the Cartri
dge
BIT
1 Interrupt Input
HIGH=
16K
CHANGEABLE=
64K
css
GM0 & I
NT
/
EXT
GM1
GM2
A/G
l
0 =
FIRQ*
to
CPU
Disabled
1 =
FIRO*
to
CPU
Enabled
0 =sets flag on falling
edge
CART*
1 =
sets
flag on rising
edge
CART
*
BIT
2
=Normall
y 1: 0 =chan
ges
FF22
to
the data direction register
BIT
3 = Six
BIT
Sound Enable
BIT
4 = 1 Always
BIT
5 = 1 Always
BIT
6 =
Not
Used
BIT
7 = Cartridge
Interrupt
Flag
FF40-
FFBF NOT USED
Figure
1-3.
Color
Computer
Memory Map
(page
3)
----------1tad1e
lhaell----------
- 8 -
Color
Computer
2
-----------TRS·BO
®
Service
Manual
The
addresses
from
FFCO
to
FFDF
are
the
control
registers
for
the
SAM
address
multiplexer
chip
(U22).
There
are
no
data
lines
to
the
SAM
chip;
therefore,
two
addresses
are
used
to
control
each
register.
In
general,
writing
any
data
to
an
even
numbered
memory
location
will
clear
the
register
and
writing
any
data
to
an
odd
numbered
memory
location
will
set
the
register.
Addresses
FFC0-FFC5
control
the
display
mode.
To
select
a
certain
display
mode,
the
display
mode
control
registers
(V0-V2)
and
the
PIA
(U2)
controlling
the
VDG
chip
must
all
be
set
to
the
proper
mode.
Addresses
FFC6
to
FFD3
control
the
display
starting
address.
If
all
of
the
registers
are
cleared,
the
display
will
begin
at
0000.
Normally,
register
F2
will
be
set
causing
the
display
to
start
at
0400.
This
feature
of
the
SAM
chip
allows
the
display
to
be
paged
through
all
of
the
RAM.
Register
Pl
controls
a
feature
which
is
not
used
in
the
Color
Computer
2.
Therefore,
is
should
be
cleared
at
all
times.
Addresses
FFD6
to
FFD9
control
the
clock
speed
of
the
CPU.
The
Color
Computer
2
is
designed
to
operate
at
0.89
MHz.
Therefore,
registers
RO
and
Rl
should
be
cleared.
Addresses
FFDA
to
FFDD
control
the
memory
size
setup
of
the
SAM
chip.
These
addresses
select
16K
or
64K
of
RAM
in
the
Color
Computer
2.
This
memory
size
option
should
be
changed
only
by
the
reset
routine
in
BASIC.
Changes
at
other
times
may
erase
the
contents
of
RAM.
Register
TY,
at
addresses
FFDE
to
FFDF,
controls
the
map
type.
If
this
bit
is
cleared,
the
ROMs
occupy
the
upper
32K
of
the
Memory Map
with
the
lower
32K
of
address
space
available
for
RAM.
If
this
bit
is
set,
the
ROMs
"disappear"
from
(are
switched
out
of)
the
map
and
all
64K
(less
the
top
256)
locations
are
available
for
RAM.
Caution
must
be
exercised
in
setting
this
bit.
The
control
program
must
be
in
low
memory
and
must
not
return
to
ROM
for
obvious
reasons.
The
final
series
of
addresses
in
the
Color
Computer
2
are
the
interrupt
and
reset
vectors.
Whenever
the
CPU
receives
a
reset
or
interrupt,
it
will
load
the
address
at
the
indicated
location
and
begin
execution
at
the
new
location.
This
dual
set
of
addresses
is
listed
because
the
vectors
are
mapped
into
the
top
of
the
BASIC
ROM
(BFF2-BFFF).
For
instance,
if
the
CPU
reads
FFFF
it
will
actually
read
the
contents
of
BFFF.
----------nad1e111aell----------
- 9 -
Color
Computer
2
Service
Manual
---
--------T
RS-80
®
-----------
-
NU
..
~32/64K
}
_
16K
Dynamic R
-4K
A
Ms
FFDF s
TY
MAP
FFDE c TYPE
-N.U
.
(=0)
_N
.
U.
FFDD s
M1
1 ,I0 0
-0
.9/1
FFDC c MEMORY
FFDB s
M0
SIZE I
FFDA
1
·0
1 0
c
.8 MHz
~
Transparent
0.9 MHz only
Refresh
FFD9 s
Rl
1 1 0 0
FFD8 c
CPU
FFD7 s
R0
RATE
FFD6 1 0 1 0
c
FFD5 s Pl
PAGE
#1
(=
0)
FFD4 c
FFD3 s F6
FFD2 c 'I
FFDl
s I
F5
FFD0 c
FFCF s
F4
DISPLAY Address
of
Upper-Left-Most
FFCE c OFFSET Display Element = 0000+ (%K Offset)
..
FFCD s
F3
N.
U.-
FFCC c
(BINARY)
-RG6,
CG6
FFCB s
F2
-RG3
FFCA c
-CG3
FFC9 s
Fl
-RG2
FFC8 c -
CG2
FFC7 s F0
I
C~
,
FFC6 c
RGl
Al,
AE,
S4
FFC5 s V2 I
FFC4 c DISPLAY 1 1 1 1 0 0 0 0
FFC3 s
Vl
MODE
FFC2 c CONTROL 1 1 0 0 1 1 0 0
FF
Cl
s V0
FFC0 c 1 0 1 0 1 0 1 0
Figure
1-3.
Color
Computer
Memory
Map
(page
4)
----
------
ltadte
lhaell----------
-
10
-
Color
Computer
2
-----------TRS-80
®
FFFF
OR
BFFF
RESET VECTOR LSB
FFFE
OR
BFFE
RESET
VECTOR
MSB
FFFD
OR
BFFD
NMI
VECTOR
LSB
FFFC
OR BFFC
NMI
VECTOR
MSB
FFFB OR BFFB SWl1 VECTOR LSB
FFFA
OR
BFFA
SWI
1 VECTOR MSB
FFF9
OR
BFF9
IRO VECTOR LSB
FFF8
OR
BFF8
IRO
VECTOR MSB
FFF7
OR
BFF7
FIRO
VECTOR
LSB
FFF6
OR
BFF6
Fl
RO
VECTOR
MSB
FFF5
OR
BFF5
SWl2
VECTOR
LSB
FFF4
OR
BFF4
SWl2
VECTOR
MSB
FFF3
OR BFF3 SWl3
VECTOR
LSB
FFF2
OR BFF2 SWl3
VECTOR
MSB
FFF1 OR BFF1 RESERVED
FFFO OR BFFO RESERVED
FFEF -FFEIJ
NOT
USED
Service
Manual
Figure
1-3.
Color
Computer
Memory Map
(page
5)
----------1tad1elhaell----------
-
11
-
Color
Computer
2
Service
Manual
-----------TRS·BO
®
-----------
--------------------nad1elhaell---------------
-
12
-
Color
Computer
2
-----------TRS-80
®
Service
Manual
2/
Specifications
2.1
Physical
1.
Size:
Width
-
14.
75"
(37.5
cm)
Depth
-
10.35"
(
26.
3 cm)
Height
-3 •
55
II
(9.0
cm)
2.
Weight:
4.75
lbs
(2.15
kg)
2.2
Power:
110
vac
60
Hz,
0.2
Amps
RMS
typical
2.3
Technical
1.
Microprocessor:
2.
Memory:
RAM:
ROM:
3.
Keyboard:
4.
Video:
5.
Sound:
Sources:
6.
cassette:
7.
RS232C:
Type
-
Motorola
MC6B09E
Clock
Speed
-
O.B96
MHz
16K
Expandable
to
64K
BK
Standard
Basic
(26-3026
)
BK
Extended
Basic
(26-3027
) ,
total
of
16K
Basic
ROM
Up
to
16K
additional
ROM
(in
cartridge)
53-key
microprocessor
scanned
matrix
RF
Modulated
output,
channel
3
or
4
32
characters
by
16
rows
Up
to
B
colors
Graphic
resolution
up
to
256
x
192
pixels
Six-bit
DAC
Single
bit
Input
from
cassette
recorde
r
Input
from
cartridge
connector
1500
Baud
Frequency
Shift
Keying
3-wire
interface
under
software
control
-----------
llad1e/haell----------
-
13
-
Color
Computer
2
Service
Manual
-----------TRS-80
®
-----------
2.3
Technical
Ccon't)
8.
Joystick:
9.
Expansion:
2
connectors,
2
axes
each,
DC
voltage
input
of
0.25
to
4.75
volts
in
64
steps
40-pin
cartridge
connector
con-
taining
all
major
CPU
signals
necessary
for
interface.
----------
lladtelhaell----------
-
14
-
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46
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