Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual page 69

• Add three state times (WAIT states) to each memory
reference to the refresh memory.
For example, the instruction LD (nn), A stores the contents
of the A register in address nn. It is a 3-byte instruc-
tion with four memory references (read operations code,
read lower 8 bits of address, read upper 8 bits of address,
and write the contents of the A register into that address).
Here are four typical cases:
Address
Case
(Hex Code) Code DescriEtion
1 1000 32 00 70 A(7000)
2 1000 32 00 80 A(8000)
3
9000 32 00 70
A(7000)
4 9000 32 00 80 A(8000)
Case 1 - All addresses in program memory
Execution time
=
13 states
1 wait
14 states
(basic)
(program memory)
=
3.5 microseconds
Case 2 - Program in program memory, write into refresh
memory
Execution time
=
13 states
1 wait
3 wait
17 states
=
(basic)
(program memory)
(write in refresh memory)
=
4.25 microseconds
Case 3 - Program is refresh memory, write into program
memory
Execution time
=
(basic) 13 states
9 wait
22 states
(three refresh memory reads)
=
5.5 microseconds
Case 4 - All addresses in refresh memory
Execution time
=
13 states
12 wait
25 states
82100083
(basic)
(four refresh memory references)
=
6.25 microseconds
4-5