Rewrite the Tiny BASIC IL program to support 7 changes to BASIC

Question

Circa 1976. With the success of the Tiny BASIC Design Note, a variety of Tiny BASIC IL implementations now span a range of microcomputers. The time has come to expand the Tiny BASIC standard.

Grammar revisions:

(LET) var = expression
INPUT (string ,) var-list
PRINT expr-list (;)
IF expression relop expression (THEN) statement
DO
WHILE expression
UNTIL expression
REM any-text

Please rewrite the Tiny BASIC program in its IL to support the revised grammar above:

1. Make the “LET” keyword optional (prevent overbyte! e.g., X = X + 1 no longer has to be LET X = X +1).
2. Make the “THEN” keyword optional (e.g., IF X=21 PRINT “BLACKJACK!” becomes valid).
3. Support the “REM” remark statement for those people who upgraded their RAM and can waste memory with comments.
4. If an INPUT statement starts with a string, output that string as a prompt (e.g., INPUT “AGE?”, A).
5. If a PRINT statement ends with a semicolon (“;”) then suppress the carriage return.
6. Implement a DO-WHILE loop.
7. Implement a DO-UNTIL loop.

Sample loop:

10 X=10
20 DO
30 PRINT X
40 X=X-1
50 UNTIL X<0
60 REM "WHILE X>=0" WOULD ALSO HAVE WORKED
70 PRINT "BLASTOFF!"

I've lightly edited the Tiny BASIC IL Reference and program here to make both easier to follow.

This is atomic-code-golf so shortest code wins, but - since no one has an IL assembler handy and since encoding of op-codes varied anyway - in this case, the fewest lines of code wins (not counting blank lines or lines with only comments; no penalty here for readability).