IMP interface for ISI and ANTS

[larsbrinkhoff]

Address	Name	Meaning
170	IMPIVI	Interrupt vector, input
174	IMPIVO	Interrupt vector, output
164000	IMPSPI	DMA input start pointer
164002	IMPEPI	DMA input end pointer (ANTS)
164002	IMPBCI	DMA input byte count (ISI)
164004	IMPS1I	Input status register 1
164006	IMPS2I	Input status register 2
164010	IMPSPO	DMA output start pointer
164012	IMPEPO	DMA output end pointer (ANTS)
164012	IMPBCO	DMA output byte count (ISI)
164014	IMPS1O	Output status register 1
164016	IMPS2O	Output status register 2

Input status register 1

Name	Value	Meaning
IMPERR	100000	IMP error
NEXMEM	040000	Nonexistent memory
BCEQ0	010000	Byte count = 0
BUYSY	004000	Busy
ENDMSG	000400	End of message
BUFULL	000200	Input buffer full
INTENA	000100	Interrupt enable
NOSWAP	000020	Suppress byte swapping
MEMEX	000006	Memory address extenstion (ISI)

Input status register 2

Name	Value	Meaning
TSTINC	002000	Test increment
LOCK	001000	Lock interface (don't start when BCI/EPI is loaded)
LOOP	000400	Loop output to input
IMPRDY	000200	IMP master ready
SCOSYN	000001	Scope sync

Output status register 1

Name	Value	Meaning
NEXMEM	040000	Nonexistent memory
BCEQ0	010000	Byte count = 0
BUSY	004000	Busy
DONE	000200	Done
INTENA	000100	Interrupt enable
NOSWAP	000020	Suppress byte swapping
MEMEX	000006	Memory address extension (ISI)
DISEOM	000001	Disable end of message

Output status register 2

Name	Value	Meaning
IRESET	000400	Interface reset
HOSRDY	000001	Host master ready

[larsbrinkhoff]

The protocol used to talk to an emulated IMP is based on UDP packets. See the SIMH files H316/h316_udp.c and H316/h316_hi.c for details.

Field	Size in octets	Value
Magic	4	ASCII "H316"
Sequence	4	Packet sequence number in network byte order.
Size	2	Payload size including flags.
Flags	2	Flag bits. 001 is end of message, 002 is IMP/host ready.
Payload		Message as per BBN Report 1822.

[larsbrinkhoff]

FYI @slcasner, these are the ISI/ANTS IMP host interface definitions found in ELF. Most of them look very straightforward.

[slcasner]

164012 should be "output" rather than "input". I agree that the interface should not be hard to simulate.

[larsbrinkhoff]

Thanks, fixed typos. I'll have this on a back burner for now.