Reference Manual

Turbo PMAC/PMAC2 Software Reference

Turbo PMAC Global I-Variables 37

I3 I/O Handshake Control

Range: 0 to 3

Units: None

Default: 1

I3 controls what characters, if any, are used by Turbo PMAC to delimit a transmitted line, and whether

PMAC issues an acknowledgment (handshake) of a command.

Note:

With communications checksum enabled (I4=1), checksum bytes are added after

the handshake character bytes.

Valid values of I3 and the modes they represent are:

0: Turbo PMAC does not acknowledge receipt of a valid command. It returns a <BELL> character on

receipt of an invalid command. Messages are sent without beginning or terminating <LF> (line feed);

simply as DATA <CR> (carriage return).

1. Turbo PMAC acknowledges receipt of a valid <CR>-terminated command with a <LF>; of an invalid

command with a <BELL> character. Messages are sent as <LF> DATA <CR> [ <LF> DATA

<CR> ... ] <LF>. (The final <LF> is the acknowledgment of the host command; it does not

get sent with a message initiated from a PMAC program [SEND or CMD]). This setting is good for

communicating with dumb terminal display programs.

2. Turbo PMAC acknowledges receipt of a valid <CR>-terminated command with an <ACK>; of an

invalid command with a <BELL> character. Messages are sent as DATA <CR> [ DATA <CR>

... ] <ACK>. (The final <ACK> is the acknowledgment of the host command; it does not get

sent with a message initiated from a PMAC program [SEND or CMD]). This is probably the best

setting for fast communications with a host program without terminal display.

3. Turbo PMAC acknowledges receipt of a valid <CR>-terminated command with an <ACK>; of an

invalid command with a <BELL> character. Messages are sent as <LF> DATA <CR> [ <LF>

DATA <CR> ... ] <ACK>. (The final <ACK> is the acknowledgment of the host command; it

does not get sent with a message initiated from a PMAC program [SEND or CMD]).

Note:

I3 does not affect how DPRAM ASCII communications are performed.

Examples:

With I3=0:

#1J+<CR> ........ ; Valid command not requiring data response

.......................... ; No acknowledging character

UUU<CR> .......... ; Invalid command

<BELL> ............. ; PMAC reports error

P1..3<CR> ...... ; Valid command requiring data response

25<CR>50<CR>75<CR> ; PMAC responds with requested data

With I3=1:

#1J+<CR> ........ ; Valid command not requiring data response

<LF> ................. ; Acknowledging character

UUU<CR> .......... ; Invalid command

<BELL> ............. ; PMAC reports error

P1..3<CR> ...... ; Valid command requiring data response

; PMAC responds with requested data