PCjs Machines

Home of the original IBM PC emulator for browsers.

Logo

IBM PC (Model 5150) with Dual Displays

The original IBM PC fully supported dual-monitor configurations, but unlike today, it was an expensive setup and required separate video cards. When the IBM PC was introduced, the only available combination was an MDA (Monochrome Display Adapter) connected to an IBM 5151 Monochrome Display, and a CGA (Color Graphics Adapter) connected to an IBM 5153 Color Display.

At any given time, only one display was considered “active”, and the initial active display was determined by switches on the motherboard. Beginning with PC DOS 2.00, you could use MODE commands to change the active display:

The initial active display for the machine below is the Monochrome Display. Third-party software with dual-display support could write to both displays simultaneously, but most text-based applications only wrote to the active display. Programs that used color graphics, on the other hand, might use the Color Display whether or not it was currently active.

IBM PC, 64Kb RAM, LPT1, COM1, MDA and CGA

Monochrome Display
Caps
Num
Scroll
Color Display
F1
F2
F3
F4
F5
F6
F7
F8
F9
F10
Esc
1 !
2 @
3 #
4 $
5 %
6 ^
7 &
8 *
9 (
0 )
- _
= +
Back
-
Num
Scroll
Tab
Q
W
E
R
T
Y
U
I
O
P
[ {
] }
7
↑ 8
9
Ctrl
A
S
D
F
G
H
J
K
L
; :
' "
` ~
← 4
5
→ 6
+
Shift
\ |
Z
X
C
V
B
N
M
, <
. >
/ ?
Shift
PrtSc
1
↓ 2
3
Alt
Space
Caps
Ins 0
Del .
Esc
Tab
F1
F2
F3
F4
F5
F6
F7
F8
F9
F10
Num
Scroll
1 !
2 @
3 #
4 $
5 %
6 ^
7 &
8 *
9 (
0 )
- _
= +
Back
-
+
Q
W
E
R
T
Y
U
I
O
P
[ {
] }
7
↑ 8
9
A
S
D
F
G
H
J
K
L
; :
' "
` ~
← 4
5
→ 6
\ |
Z
X
C
V
B
N
M
, <
. >
/ ?
Shift
PrtSc
1
↓ 2
3
Ctrl
Shift
Alt
Space
Caps
Ins 0
Del .