Tandy 1000 HX Technical Reference Manual page 227

OPTION
OPTION
OPTION
OPTION
#1
#2
#3
#4
MCFO
f
MCFl
CODE
00
01
10
11
MEMORY
ORGANIZATION
BANK 0
BANK 1
BANK 2
BANK 0
BANK 1
BANK 2
BANK 0
BANK 1
BANK 2
BANK 0
BANK 1
BANK 2
64K x 8
64K x 8
EMPTY
256K x 8
EMPTY
EMPTY
256K x 8
256K x 8
EMPTY
64K x 8
64K x 8
256K x 8
ADDRESS
0.0000-0.FFFF
1.0000-1.FFFF
0.0000-3.FFFF
0.0000-3.FFFF
4.0000-7.FFFF
0.0000-0.FFFF
1.0000-1.FFFF
2.0000-5.FFFF
ACCESS
CONTROL
SIGNAL
RAS0
RAS1
RAS0
RAS0
RAS1
RAS0
RAS1
RAS2
Figure 1 MEMORY CONFIGURATION MAP
EQUATIONS FOR RAS-B
64K DRAMS require address A0-A15, therefore A19-A16
determine access.
256K DRAMS require address A0-A17, therefore A19-A18
determine access.
RAS0B = /MCF1./MCF0./19./18./17./16./REFRESH.(MEMRB+MEMWB) OPTION #1
+ /MCF1. MCF0./19./18. /REFRESH.(MEMRB+MEMWB) OPTION #2
+ MCF1./MCF0./19./18. /REFRESH.(MEMRB+MEMWB) OPTION #3
+ MCF1. MCF0./I9./I8./I7./I6./REFRESH.(MEMRB+MEMWB) OPTION #4
+ REFRESH.MEMRB
RAS1B = /MCF1./MCF0./19./18./17. 16./REFRESH.(MEMRB+MEMWB) OPTION #1
+ MCF1./MCF0./19. 18. /REFRESH.(MEMRB+MEMWB) OPTION # 3 ,
NO OPTION #2
+ MCF1. MCF0./19./18./17. 16./REFRESH.(MEMRB+MEMWB) OPTION #4
+ REFRESH.MEMRB
RAS3B « MCF1. MCF0,/19./18. 17
+ MCF1. MCF0./19. 18./I7
+ REFRESH.MEMRB
/REFRESH.(MEMRB+MEMWB) OPTION #4,
NO OPTION #1,#2,#3
/REFRESH.(MEMRB+MEMWB)
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