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PMAC 2 Software Reference

258 PMAC On-Line Command Specification

Scope

Global

Syntax

M{constant}[..{constant}]->TWD[:]{multiplex

address},{offset},{size}[.{dp}],{format}

where:

• {constant} is an integer from 0 to 1023 representing the number of the M-variable;

• the optional second {constant} must be at least as great as the first {constant} – it

represents the number of the end of the range;

• {multiplex address} is an integer constant in the range 0 to 255, representing the

address in the multiplexing scheme on the thumbwheel port of the most significant digit

(lowest address) to be used in the M-variable(s);

• {offset} is 0 or 4, representing whether the most significant digit is in the low nibble

(left digit of pair) or high nibble (right digit of pair) of the pair of digits at {multiplex

address}, respectively;

• {size} is an integer constant from 1 to 12, representing the number of digits to be used

in the M-variable(s);

• {dp} (optional) is an integer constant from 0 to 8, representing the number of these

digits to be interpreted as being to the right of the decimal point;

• {format} (optional) is either U for unsigned, or S for signed. If it is signed, the least

significant bit of the most significant digit is taken as the sign bit (the rest of the most

significant digit is ignored). If no format is specified, U (unsigned) is assumed.

Note:

No spaces are permitted between the M-variable name and the arrow

double character in this command.

Remarks

This command causes PMAC to define the specified M-variable or range of M-variables to

point to a set of binary-coded-decimal digits multiplexed on the thumbwheel port with

Accessory 18 or compatible hardware.

Thumbwheel-multiplexer M-variables are read-only, floating-point variables. Once defined,

they are to be used in expressions, and queried. Each time one is used in an expression, the

proper addresses on the multiplexer board(s) are read.

Example

M100->TWD:4,0,8.3,U means the most significant digit is at multiplex address 4, low

nibble (left digit); there are 8 digits, 3 of which are fractional; and it is always interpreted as a

positive value. This corresponds to eight thumbwheel digits along the bottom row of the

lowest-addressed thumbwheel board, with the decimal point 3 digits in from the right.

M99->TWD:0,0,1,U means that a single digit is used, at multiplex address 0, low nibble

(left digit). This corresponds to the upper left thumbwheel on the lowest-addressed

thumbwheel board.