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13;:~~~
0
Pr'ocf.~~:;~:;or
Module
13~?20·M·91
OB7
/1.1
R
(~v
J
AN .. -()
4·-S;:!.
3.2
MEMORY SECTION
~3.
2.1
The Z80A is
capable of addressing 65536
(64K)
bytes
of MeMory data.
The MeMory Map for this processor is'shown in the table below.
OOOOH
2000H
4000H
TABLE
S.O
TerMinal MeMory Map
NMI Service Routine
S~~lf
t€~st
code
Function keys code
l)at .. :lCOMM code
Configuration code
Video intrinsics
U63
HK
16K
U6S
~~41<
6000H
I
Internal printer code
I
I
U66
~5:r:.!\(
I ................ _. - ..................... M ..................... _ ..................... _ .............. M' ........ M ...... _ ..................... _. _. M ... M ......... _. _ ... M.
BOOOH
I
Not
u~:;ed
I
(CRTC Map)
I
U67
I
40K
I ......................................... - ............................ "" ............................ _ .............. -................................. _ ..
M . . . . . . . . . . . . . . . . . . . . . . . . .
I
AOOOH
I
Not
us(~d
I
I
(CRTC Map)
I
I
U68
I
4BK
I ........................................ _.
'M' 'M'"'' ........ - ' - ......................... -
.................... _ .............................................................. _ ..
I
CO () OH
I
DynaMic
I~AM
I
I
- buffers
I
I
- display MeMory
I
I
- stack
I
I
- systeM variables
I
I
I
I
ZDO : ZDt : ZD2 : ZD3 : ZD4 : IDS :
ID6 :
ID7
I
I U41 : U42 : U43 : U44 : US1 : US2 : US3 : US4 I 64K
R€~a
d· . . · on 1 y ·· ..
M(-:~Mor
y
As
can
be seen
frOM the MeMory
Map 4B K
of address
space has been
allocated
for read-onlY-MeMory
(ROM).
This MeMory contains the
ZaOA
prograMS which
controls the
terMinal
operation.
The
ROM space
is
decoded into six 81< byte blocks
by the 74LS138 decoder U76.
A JUMper
on address bit TA12 for each ROM allows the use of either BI< byte or 41<
byte
ROMs
(or
EPROMs).
Note
that
BK
bytes of
address
space is
allocated
for
each ROM device even
if it is only a 4K byte ROM
(the
upper
41<
of that block is unusable).
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