15
The following diagram illustrates how the words and bits allocated to the ASCII
Unit relate to program execution.
PC
ASCII Unit
Application
Program
MOV/OUT
Output Data
Input Data
PC PUT
PC GET
PC WRITE
PC READ
BASIC
Program
Common
Memory
n+1 08 to 15
n+3 08 to 15
MOV/LD/OR
MOV(21/030)
MOV(21/030)
Write data in n
Read data in n+2
Timing
The following diagram illustrates the various timing relationships between the
PC and ASCII Unit during data transfer.
Relationship between READ and WRITE Timing
PC busy: n+1 (00)
Write/Read data: n or n+2
PC write complete: n+1 (01)
PC read complete: n+1 (02)
ASCII busy n+3 (00)
ASCII read complete: n+3 (01)
Read data: n
PC Unit
↔
common memory
common memory
→
ASCII
Write data: n+2
ASCII
→
common memory
ASCII write complete: n+3 (02)
PC WRITE
PC READ
PC
→
ASCII
ASCII
→
PC
PC READ
PC WRITE
ASCII READ
ASCII WRITE
Application program
BASIC Program
Relationship between Output and Input Timing
Output data
PC
→
ASCII: n+1 (08 to 15)
Input data
ASCII
→
PC: n+3 (08 to 15)
I/O refresh
PC
→
ASCII
ASCII
→
PC
PC
→
ASCII
ASCII
→
PC
Program Execution
Data Configuration
Summary of Contents for C500-ASC04
Page 1: ...C500 ASC04 ASCII Unit Operation Manual Revised February 2001 ...
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