Commodore 128 Programmer's Reference Manual page 638

628 COMMODORE 128
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TIMING SPECIFICATION ~
INTERNAL ROMs
This section specifies timing parameters for both the 23128 and the 27256 Read Only
Memories. This timing spec applies to internal ROMs and for external ROMs run at 1
MHz. For external ROMs run at 2 MHz, see Table 16-18.
PARAMETER SYMBOL
Tacc
Tce
Toe
MIN
300
300
120
MAX
—
TO
ns
ns
ns
Address Valid to Output Delay
Chip Enable to Output Delay
Output Enable to Output Delay TOE 120 — ns j )
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Table 16-17. Internal ROM Timing
RDDRESS v,
CHIP
ENflBLE
OUTPUT
ENflBLE
DRTfl
^AAAAAAAAATX y^AAAA^
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Figure 16-25. ROM Timing Diagram
EXTERNAL ROMS
All C64 mode external ROMs and many C128 mode external ROMs can be of the type
mentioned above. Any external ROM that is to run at 2 MHz must be faster, as
specified in Table 16-18.
PARAMETER SYMBOL MIN MAX UNIT
Address Valid to Output Delay TACC 250 — ns
Chip Enable to Output Delay TCE 200 — ns
Output Enable to Output Delay T0E 100 — ns
Table 16-18. External 2MHz ROM Timing
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