RCA 70/46 User Manual

Input/Output Operation
Block 4- • If the service request comes from a device control electronics con-
nected to
the multiplexor channel, the processor uses the device address
to fetch the appropriate subchannel registers in non-addressable main
memory. The sub channel registers are stored in the input/output channel
registers in scratch-pad memory for the multiplexor channel.
Block 5
• A test is made to see if this is a terminating interrupt. If it is not
(it is a program controlled or a device request interrupt) control is trans-
ferred to Block 8.
Block 6 • If the interrupt is a terminating interrupt, the termination interrupt
bit in the channel status byte is set.
Block 7
• A test is made to see if the byte count is not equal to zero and the
Suppress Length Indicator (SLI) flag is equal to zero. If these conditions
are present, the program desires an indication of incorrect length and the
incorrect length
bit in the channel status byte is set.
Block
8 • The standard device byte is stored in the appropriate input/output
channel registers and program control continues with the next instruction.
Notes om Interrupt Servicing:
1. The device address is always stored in the input/output channel
registers in scratch-pad memory if the interrupt is due to a device
connected
to the multiplexor channel. If the interrupt is due to a
device on a selector channel,
the device address is stored only if it
is a device request interrupt.
2. If a main memory parity error occurs when fetching the subchan-
nel registers,
the channel control check bit in the channel status
byte is set.
80

RCA 70/46 Specifications

General

Brand	RCA
Model	70/46
Category	Computer Hardware
Language	English