12/TechnicalInformation
This section is intended for Z-80 programmers and BASIC programmers who are
familiar with binary and hexadecimal arithmetic and hardware concepts like bit and
byte. Its purpose is toallow you to take full advantage
of
the Model III TRS-80.
Ifyou wantto understand and use the systemon this level, butdo nothave the
background,
we
suggestyou read:
TRS-8oAssembly
Language Programming
byWilliam Barden, Jr.
Radio
Shack
Catalog Number62-2006
This one bookwill
get
you
off
to a good start. It was written for the Model I TRS-80,
butalmost all
of
itapplies to the Model III as well.
ToProtect High
RAM
In many applications, you will wantto interface a BASIC programand a Z-80
routine. In such cases, you need to protectenough high RAM to accommodate your
Z-80 routine. Otherwise, BASIC will use all RAM available for storage and execution
of
the BASIC program.
During the start-up dialog, you have the option
of
protecting high RAM via the
Memory Size Question.
Ifyou simply press
(ENTER)
to this question, BASIC will use
all available
RAM.
To
protect
RAM,
type in
the'
'limit address" in decimal form, and then press
(ENTER).
The limit address is the highest memory address you want BASIC to use.
Addresses above this value will not
be
affected by BASIC.
Forexample,
if
youtype: "32667
(ENTER)",
BASIC will not use any memory above
32667.
It
will use 32667 and all lower-numbered memory locations.
12/1
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