Tandy 1000 SL Technical Reference Manual page 110

PORT F F E 9
-
WRITE/READ
B I T
0 :
0 = Z e r o W a i t s t a t e s f o r I n t e r n a l M e m o r y
B I T D e s c r i p t i o n
1 - 2 B i t 2 B i t 1
1 = O n e Wait
S t a t e
f o r I n t e r n a l M e m o r y
0 0
Zero Wait S t a t e s f o r I n t e r n a l M e m o r y
0 1 O n e W a i t S t a t e
f o r I n t e r n a l
M e m o r y
1 0 Two W a i t S t a t e s f o r I n t e r n a l M e m o r y
1
1 T h r e e W a i t S t a t e s f o r I n t e r n a l M e m o r y
0
0
Z e r o
W a i t
S t a t e s f o r CPU I / O c y c l e
0 1
O n e Wait S t a t e f o r CPU I / O c y c l e
1
0
Two W a i t S t a t e s f o r CPU I / O c y c l e
1 1
T h r e e W a i t S t a t e s f o r CPU
1/0
c y c l e
B I T D e s c r i p t i o n
3-4 B i t 4 B i t 3
B I T 5: 0 = E a r l y Write S t r o b e f o r DMA c y c l e
1
=
N o E a r l y Write S t r o b e f o r
DMA cycle
B I T 6:
0
=
Z e r o W a i t S t a t e s f o r 1 6 B i t V i d e o
1 =
O n e
W a i t
S t a t e f o r 1 6 B i t V i d e o
B I T 7: M u s t be 0 w h e n O S C I N i s e q u a l t o 2 8 . 6 3 6 3 6 M H z
M u s t be
1
w h e n O S C I N is e q u a l t o 2 4 MHz ( d e f a u l t )
PORT FFEA
-
WRITE/READ
B I T 0: ROM' PAGING 0
B I T
1:
ROM PAGING
1
B I T 2: ROM PAGING 2
B I T
3:
ROM PAGING 3
B I T 4 : ROM PAGING 4
B I T 5: N o t U s e d
B I T
D e s c r i p t i o n
6-7
B i t 7 B i t 6
0 0 Two B a n k s of 1 2 8 K m e m o r y
0 1 F o u r B a n k s
of
128K m e m o r y
1 0
O n e B a n k of 5 1 2 K m e m o r y
1 1
O n e B a n k of
512K
m e m o r y , O n e B a n k of 128K m e m o r y
NOTE:
When r e a d i n g P o r t F F E A , b i t
4
w i l l
be
i n v e r t e d f r o m w h a t w a s w r i t t e n ,
(i.e. w h e n a
0
w a s w r i t t e n , a 1 w i l l be read; w h e n a
1
w a s w r i t t e n , a
0 w i l l
be read.)
1 7