geller@rlgvax.UUCP (05/10/84)
COMPUTE!, May, 1984
-------------------
Chris Clark, writing in the May, 1984 issue of Compute! magazine, explained
why the implementation of BASIC in the Texas Instruments home computer is
notoriously slow.
"TI BASIC is indeed slow, due to the unusual architecture of the machine and
the design of the BASIC interpreter. First of all, the RAM in which BASIC
programs are stored is not CPU RAM. The 16K of RAM in the 99/4A is maintained
by the TMs9918A video display processor (VDP). There are only 256 bytes of
CPU RAM."
"Every time the the microprocessor accesses or RUNs a BASIC progra, it must
request the program from the VDP one byte at a time."
"...the interpreter itself is not written in machine language. It is written
in another high level language known as Graphics Programming Language, or
GPL."
"This is similar to writing a BASIC interpreter in BASIC for an IBM PC. It is
realy amazing that the TMS9900 can run BASIC as fast as it does, considering."
There you have it. You can find the little article on page 12 of the May
issue of Compute!. I found this to be quite interesting as well as very
surprising.
David P. Geller
Computer Consoles, Inc.
{seismo}!rlgvax!geller Office Systems Group
11490 Commerce Park Drive
Reston, VA 22091
703-648-3483
(...of course these are my OWN views!)