INMC News

  

April/May 1980, Issue 7











Page 6 of 39











feelings on seeing my FRUIT MACHINE in Issue 5 but I am only too happy for other members to benefit. (Eddie Pounce is the common factor). This was the first program I wrote for our NASCOM some 12 months ago. The coding is not very elegant and the documentation is hand written and covers some 18 sheets so I do not think it worth putting in the library, especially now everyone has the object code. For those who like to fiddle, the three barrels are 16 bytes long each and occur starting from 0C96. As set up, the player makes a steady profit if cherry equivalents (✓) are held whenever possible. The jackpot odds are 1:4096 with no hold, 1:256 with one hold and 1:16 with two holds. Bon chance!

Yours,
Gordon Alabaster
Berkhamsted, Herts.

BASIC FACTS

Dear INMC,

Now for some flattery. I think that INMC news comes close to providing the best personal computing magazine going – no doubt because it only deals with Nascoms and not the plastic horrors available elsewhere.

The reason I am writing, however, is concerning the Nascom 8K ROM BASIC. I recently received my expensive piece of plastic and silicon and have been playing with it ever since. In the the course of this experimenting I have come up with a few facts that the grotty documentation ignores. For all I know I may be reinventing the wheel, but as I am an assiduous, not to say compulsive reader of computing magazines, and have not seen this info. published elsewhere, it may be helpful to pass on to our beloved readership.

1) As is well known, the BASIC reserved words, such as READ, DIM, PEEK etc. are stored as single bytes, using hex values of 80 and above. How to find what byte represents what word?

Examination of the BASIC text storage area shows that it always starts at address 10FAH and each line of text has the following format:

Bytes 1 and 2. : Address of next line, or free memory if line is the last line. Least significant byte first.

Bytes 3 and 4 : Line number in hex. L.S.B. first.

Bytes 5 to N-1l : The text string.

Byte N : 00H, which acts as line terminator.

For example, the BASIC program,

10 PRINT "HELLO"
20 END

This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 6 of 39