IBM Personal System/2 65 SX User Manual

Bits
7-4
Bits
7
through
4
provide
the
memory
card
ID.
m
o
o ~A
|| Bits
||
7654
Size
Speed
0000
v
4MB
80
ns
oo01/
2MB
100
ns
||
oo10¥
1MB
100
ns
|]
0011-0100
Reserved
-
cl
poor
f
[|
0101
2MB
az
Fangy
ps
ASS,
os
pee.
|]
0110.
IMB
GO
x¢p2y
Sg
§5,5)
we
||
0111-1100
Reserved
-
||
11014
2MB
120
ns
i]
1110/
1MB
120
ns
|]
at14/
No
memory
card
-
|
installed
Figure
2-8.
Memory
Card
ID
Bits
| 4MB Memory Cards
|
Blts
3-0
When
set
to
1,
a
4MB
memory
card
is
enabled
|
IMB
and
2MB
Memory
Cards
|
Bits
3,
2
Reserved
|
Bit4
When
set
to
1,
this
bit
enables
the
second
1MB
ona
|
2MB
memory
card.
|
BitO
When
set
to
1,
this
bit
enables
a
1MB
memory
card
or
|
the
first
1MB
on
a
2MB
memory
card.
System-Board
POS
Register
5
(Hex
0105)
This
is
the
memory-control
register.
Bit Function
7,6 Reserved
5
640KB
-
1MB
Split
Enable
4 ROM Enable
3
Memory-Access
Speed
2-0
Memory-Connector
Select
Bit
for
POS
Register
4
Figure
2-9.
System-Board
POS
Register
5
(Hex
0105)
Bits
7,6
These
bits
are
reserved.
Bits
When
set
to
0,
this
bit
enables
the
system-board
RAM
between
640KB
and
1MB.
Typically,
128KB
of
this
memory
is
mapped
to
the
system-board
ROM
address
Space,
and
the
remaining
256KB
is
mapped
to
the
first
2-10
Model
65
POS
—
October
1990

IBM Personal System/2 65 SX Specifications

General

Brand	IBM
Model	Personal System/2 65 SX
Category	Desktop
Language	English