Memory - AMSTRAD cpc 6128 User Instruction

Part 14: Memory
The CPC6128 contains 128K of RAM, and 48K of ROM. This is available to BASIC
1.1 as shown below. The first 64K of RAM is nominally divided into four blocks (each
of16K) numbered Block 0 to Block 3. The screen uses Block 3 and the upper section of
Block 2 is filled by system variables as indicated.
FIRST 64K OF RAM
SECOND 64K OF RAM
(unused)
h
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FIRMWARE DATA AREA 1
JUMP BLOCK 1
BASIC DATA AREA I
DISC ROM DATA AREA I
ANY I OTHER RaMS' DATA AREA :
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BASlt PROGRAM AREA 1
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NOTE l' DEPENDS ON EXTERNALLY FITTED ROMS-&A6FC WHEN NO EXTERNAL ROMS FITTED
Memory Map for BASIC 1.1
The user defined characters are initially positioned immediately above HIMEM.
HIMEM may be altered by a M E M 0 R Y command but is also automatically lowered by
4K
to
create a buffer whilst AMSDOS files are open. The number of user defined
characters can only be altered if HIMEM is unchanged since the last time they were
set (unless the last time they were set to 'no user defined characters' by a S Y M B 0 L
AFT E R 256 command). When BASIC starts, the user defined characters are set as
if a S Y M B 0 L AFT E R 2 4
0
command had been issued.
It is, therefore, prudent to collapse the user defined character area before
permanently changing HIMEM, then re-establishing the user defined characters in
the new position. This will allow subsequent programs to alter the
S Y MBO L AFT E R assignment.
Chapter 7 Page 46 For your reference ....