Tandy 1000 Basic Reference Manual page 354

Chapter 11 I Technical Information
The
/M:
switch sets the highest memory address that BASIC can
use. The value that you specify with the
/M:
switch tells BASIC
that it can use all memory up to that offset. Load your subrou-
tine at that offset. Using the iM: switch prevents BASIC from de-
stroying your subroutine. For example,
B A S I C
/M:&HF000
sets the highest memory location that BASIC can use at hexade-
cimal address
EFFF.
This reserves the highest 4K bytes of
memory for your subroutine. You can load your subroutine at
hexadecimal address
&HF000
like this:
BLOAD "SUBA.ASM", g H F 0 0 0
Stack Space
If you need more stack space when you call an assembly lan-
guage subroutine, you can save the BASIC stack and set up a
new stack for the subroutine. You must restore the BASIC stack
before returning from the subroutine. You save the stack, create
a new stack, and restore the stack in your subroutine.
Loading the Subroutine into Memory
You can use the operating system or the POKE statement to load
the subroutine into memory. You may assemble the routines
with the Macro Assembler (available through your Radio Shack
dealer) and link them with Linker. The Linker is part of the
MS-DOS
package. To load the program file, observe these
guidelines:
0
Be s u r e t h a t t h e subroutines do not contain any long
references.
Skip the first 512 bytes of the LINK output file and then
read in the rest of the file.
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