RCA Spectra 70 User Manual

APPENDIX C
INPUT /OUTPUT
SERVICE REQUEST
Spectra 70/46 Processor Times
I/O Channel Service Times and (Microseconds)
Processing Mode
70/46
A. Selector Basic Times
1. Read/Write (Scratch Pad)
NA
2.
Read/Write (Main Memory Normal)
1.44 (2 bytes)
3. Read/Write (Main Memory less than 4-bytes; NA
CCW specified)
4.
End Service 3.12
B.
Selector Add'l Times (to be added to above times)
1.
Data Chaining
7.20 (read)
8.16 (write) (e)
2. Command Chaining
3.04 (read)
6.0 (write) (e)
3. Transfer in Channel
3.84
4. Status Modifier
1.92
5. Incomplete Read (Device Terminated in middle of
NA
word; not indicated by CCW)
C.
Multiplexor Basic Times
1. Read/Write (Multiplex Mode; non-catch-up)
13.92(a)
2. Read/Write (Burst Mode)
1.92(a)
3.
END SERVICE (Mux Mode)
10.08(a, d)
4. END SERVICE (Burst Mode)
7.68(a,
d)
D. Multiplexor Add'l Times (to be added to above items)
1. Data Chaining Mux Mode
12.96
2. Data Chaining Burst Mode
13.44
3. Command
Chaining Mux Mode
12.96(b)
4. Command Chaining Burst Mode
6.72(b)
5. Transfer in Channel
4.32
6. Status Modifier
1.92
7. Catch-up each additional byte
1.92
E. Processing Mode Times
1. START I/O (addr. the selector)
32.64(b)
2. START I/O (addr. the multiplexor)
39.6(b)
3.
Multiplexor Program Interrupt
25.90(b)
4. Selector Program Interrupt
18.86(b)
NOTES:
a. Because of odd/even ROM addressing, banking may result in loss of 2 EO cycles
(or 0.96 p.s); which will probably occur both at the beginning and at the ending
of the service; randomly this is a 50% change, or an additional time of 0.48 p.s.
b. Times are for processor servicing and are extended by Channel Response Time
(CRT).
c. The additional time required for the command and data chaining for write com-
mands is needed for buffer loading in the selector channel on the 70/46.
d. Buffered devices require two (2) end services for multiplexor operations. If the
multiplexor is operating in the Burst Mode, the first end service is done in the
Burst Mode and the second end service is done in the normal Mux Mode.
239

RCA Spectra 70 Specifications

General

Brand	RCA
Model	Spectra 70
Category	Computer Hardware
Language	English