FP6000 PROJECT MEMORANDUM NO. 10
July 11, 1962
Brief description of the control of a peripheral by the computer.
Summary of all wires between a peripheral control and the compute
Permissible loading and required drive on all connecting lines.
Standard Pin Connector for all Computer-Control Unit wires.
Designated meaning to each peripheralstate bit on read and
write buses.
1. Operation
Earning - This description is generalised and may not be applicable to
any given peripheral.
A transfer to or from a peripheral is initiated by th©
executive following an order.
The executive interrogates the state of the peripheral via
executive select and the read bus (see sec. 9 for details). The wriue
buses are all zero at this time. The interrogation will also take place
at the request of a peripheral when the control unit raises "peripheral
incident."
The executive sends "start" to the peripheral using executive
select and the write bus (see sec. £)«
Executive plays no further part in the proceedings until the
peripheral alerts it with "Peripheral Incident."
The peripheral raises "Hesitation Request" when it has found
the information or is ready to receive it.
The computer sends "Hesitation Select" informing the peripheral
that the "reset",- "stop", and "Parity Fail" buses now apply to it#
Data is read or available when "reset" is raised.
"Hesitation Request" should now be dropped (releasing
‘‘Hesitation Select") and raised again for the next word or character.
-2-
If the computer decides that the transfer is complete*
’‘stop” will be raised the bit before “reset"* and for incorrect
transfers “Parity Fail" will be raised the bit after "Reset".
“Stop" will always be sent by the computer after 123
characters from a slow peripheral or $22 worms from a fast peripheral.
The peripheral should inform Executive of any unusual .
conditions* i*e. Parity Fail* Stop etc. via "peripheral incident." ■
finals
The following list is a complete list of all standard wires
connecting any peripheral control to the computer. The preceding
sign indicates polarity when activated* or a "one."
2.1 Computer to control unit
Buses
- hrite bus
+ Select bus
Clock
+ Freeze
Lines (individual, to peripheral)
+ Hesitation select l/P
+ Hesitation select 0/P
2.2 Control Units To Computer
Buses
+ Read bus	21* and parity
Lines
+ Hesitation request l/P
+ Hesitation request 0/P
FP6000 PROJECT MEMORANDUM # 28
PHERIPHERAL DESIGNATIONS FP6OQQ -Ut-$,-6,-7,-8.
The following Special Register Nos. and Control Word locations
have been assigned:
(0 is Most Sig. Bit) Unit Bit in S.K. #61*			Control Word	Special Register
Typewriter In	u		66	2
Out	£		67	3
Paper Tape Reader #1	6	■■ v	68	u
Paper Tape Reader #2	7		69	5
Paper Tape Punch #1	10		72	8
Paper Tape Punch #2	11		73	9
Line Printer	Ih		76	12
Card Reader #1	16	• ' M %	78	Hi
Card Reader #2	17		79	15?
Card Punch	IS	-	80	' 16
Magnetic Tape #1 f fj		|	86	22.
		[ In SR #6$	87	23
#3 1	*2	r [	88	2U
§h	3		89	2£
#5		i	90	26
Drum	20		82	18
Time Acc. Reg. EMS:bf	• 3		Nil	1 E. M."strain. Data Systems Dept.
Distribution: I. Sharp y/ A. Sharp R. Whittall		• G. Collins H. Reddering J. Parsonage		* -
P« Stevens		B. Ovenall E. Strain		