FILE MANAGER
SECTION 3.3
3,3,4
3,3,5
3,3.6
3,3,7
FILE ERRORS
Each time a file is modified an error checksum is calculated and
stored in the directory. This operation is completely
transparent, as is each accuracy check when the file is accessed
for reading or executing. If any discrepancy is found then a
"no file" message is displayed.
HUNTER MEMORY ORGANISATION
HUNTER is designed for very large RAM memories and 48k ROM, see
Fig 3.1, HUNTER MEMORY MAP and Fig 3,2, HUNTER FILE ACCESS. The
memory is organised into pages: one page of ROM operating
system, one page of RAM execution memory and further pages of
RAM file space. All pages except for RO, the execution memory
(also known as the Transient Program Area, or TPA) are limited
to 48k. RO extends to 54k, although the top 6k together with the
1 Ok of common RAM are never paged out. There is, therefore, up
to 54k of RAM for programming.
Common RAM, see Fig 3,3, SYSTEM RAM MEMORY MAP, is used to link
together the various pages of RAM and ROM. It organises the
paging and contains the jump tables for CP/M compatibility. The
~operation of paging is totally transparent to the user so HUNTER
'is seen to have 54k program space with a powerful 48k operating
system and Basic interpreter in ROM, and a block of file space.
BASIC PR<XiRAHHING
Since the Basic interpreter resides in ROM, the whole 54k of RO
is available for a Basic source program, variables and arrays.
Simple variables are stored with the source program and Basic
may access files for further storage.
CP/M PR<XiRAHHING
'Object code programs must be executed from RO, Again, there is
54k RAM available for the program, plus the file space.
Normally, the program will reside in the HUNTER as a .COM file,
and will be loaded and run by the File Manager. However, the
File Manager is very versatile, and provides flexibility in
file manipulation and execution.
VER.V09F
PAGE 3 ,;. 5.
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