DESCRIPTION OF USER PART OF REX 6000 MEMORY

Last updated: Wed Feb 27 17:15:38 2002
(C) Marek Wodzinski (majek<at>mamy.to)
Update: John Heasley <heas@shrubbery.net> - a few grammatical
        and typographical corrections
Probably any new version of this document will be available from:
http://rex.mamy.to

0. TABLE OF CONTENTS
  1. INTRODUCTION
  2. KNOWN THINGS (PROVEN)
    2.1 SESSION
    2.2 LOGICAL PAGES
    2.3 DSSR COMMAND
    2.4 DSSW COMMAND
    2.5 PAGE FORMAT
      2.5.1 PAGE AND 'BIG' PAGE
      2.5.2 DATA FIELDS IN PAGE
      2.5.3 RECORD FORMAT
  3. SPECULATIONS (UNPROVEN)
    3.1 SPECIAL PAGES
      3.1.1 PAGE FFFF
      3.1.2 PAGE 0000
      3.1.3 PAGE 0001
    3.2 HOW TO FIND DATA
      3.2.1 START
      3.2.2 DATABASE DEFINITIONS
      3.2.3 READING DATABASE
      3.2.4 FIELD TYPES
      3.2.5 DATABASE NUMBERS
  4. WHAT IS NEEDED


1. INTRODUCTION
This is summary from my work on serial communication with Rex 6k.
User memory - logical pages of Rex memory witch we can read or write
with DSSR or DSSW commands.
All sync software use these commands to synchronize with Rex 6000.
Please send all bugs, corrections or updates (in text too) to majek<at>mamy.to.

2. KNOWN THINGS (PROVEN)

2.1 SESSION
Every session starts from reading:
a) page FFFF
b) page 0000
c) page 0001
For descriptions of these pages see 3.1

2.2 LOGICAL PAGES
a) every page has maximum 512 bytes
b) for now, it is not known how many pages exist.
c) pages are read with the DSSR command (details see 2.3)
d) pages are written with the DSSW command (details see 2.4)
e) these are on top of physical pages which you know from DSFR, DSFW
   or DSFE commands and they ARE NOT the same.

2.3 DSSR COMMAND
format:
DSSRxxxxyyyyzzzz0001cc\x0A (nl on end of line)
xxxx - logical page
yyyy - offset (where to start reading)
zzzz - how much data you request
cc   - checksum (sum of all previous bytes modulo 256).
all fields are in ascii hex.

response:
a) succesfull:
OKzzzzcc\x0A
datadatadatacc\x0A
zzzz - how much data you get. This may be different from value requested.
cc   - checksum
datadatacc - requested data (binary) ended with ascii checksum and nl (newline)

b) unsuccesfull
NGxxxxcc\x0A
xxxx - error number
cc   - checksum
This error ocurs when logical page are not yet used.

2.4 DSSW COMMAND
I haven't tried this yet:-)

2.5 PAGE FORMAT
a) each page contains records
b) if a record is longer than one page (up to 512 bytes), then pages are linked
   together into one 'big' page.

2.5.1 PAGE AND 'BIG' PAGE
First 3 words (6 bytes) from page are:
offset:len:description
0000:2 total length of page (including this field). LSB is first. If this
       is a 'big' page and there is first page, then this field contains
       sum of the length of the first page and the logical length of other
       pages (page length-6).
0002:2 if the page is 'big', then you have pointer to next page.
       0000 otherwise.
0004:2 if the page is 'big', then you have pointer to previous page.
       0000 otherwise.
Exceptions: page FFFF

2.5.2 DATA FIELDS IN PAGE
offset:len:description
0006:2 number of records in page (word - 2 bytes)
0008:v record,record,record....
Exceptions: pages FFFF and 0000

2.5.3 RECORD FORMAT
offset:len:description (offset in record - not in page!)
0000:2  total length of record
0002:v  body
end:2   total length of record
example:
08 00 0C 00 00 00 08 00
For more info/speculations see 3.2

3. SPECULATIONS (UNPROVEN)

3.1 SPECIAL PAGES

3.1.1 PAGE FFFF
example:
DSSRFFFF00000200000197
C0 15 BD 14 C3 01 00 00
description:
probably checksum?

3.1.2 PAGE 0000
example:
DSSR00000000020000013F
0E 00 00 00 00 00 00 00 3D 01 00 00 00 00
description:
pointer to first unused page?

3.1.3 PAGE 0001
example:
DSSR000100000200000140
42 00 00 00 00 00 06 00 08 00 0C 00 00 00 08 00   B...............
0A 00 33 00 00 00 E8 03 0A 00 0A 00 0B 00 00 00   ..3.............
EA 03 0A 00 0A 00 18 00 00 00 D2 07 0A 00 0A 00   ................
24 00 00 00 BB 0B 0A 00 0A 00 2F 00 00 00 A4 0F   $........./.....
0A 00                                             ..
description:
6 user data:
1 pointer (000C) to other databases which id is not in this page.
2-6 pointers to other databases:
page/database (see export database from RexToolsBeta)
0033/03E8(1000 - ?)
000B/03EA(1002 - adress categories)
0018/07D2(2002 - ?)
0024/0BBB(3003 - memos?)
002F/0FA4(4004 - pictures?)
For details see 3.2

3.2 HOW TO FIND DATA

3.2.1 START
Read page 0001.
On this page you have only pointers to records with descriptions of databases.

a) First record (with length 08):
offset:len:description
0000:2	length (0008)
0002:2	pointer to page contains definitions of databases with id 
	from 1 to XX, where XX is less than database_id in next record.
0004:2  ?? (usually 0000)
0006:2  length (0008)

b) Rest of records
offset:len:description
0000:2	length (000A)
0002:2	pointer to page cointains definitions of databases with id
	from YY to XX, where YY is in next field and XX is less than
	database_id in next record.
0004:2	?? (usually 0000)
0006:2	YY
0008:2	length (000A)
Now if you have database_id, you can find the page with definitions of this
database.

3.2.2 DATABASE DEFINITIONS
On page with database definition you can find several records. You must
find suitable record with exact database_id.
offset:len:description
0000:2	length of record
0002:2	0000
0004:2	?? (usually 0000)
0006:2	database_id
0008:E	??
0016:2	number of fields
0018:4	??
001C:1	field type (see 3.2.?)
001D:1	field size?
001E:2	??
0020:1	field type
0021:2	field size?
0022:2	??
....
????:2	pointer to page with data
????:??
?END:2	length of record
If you now have number of fields, fields types and pointer to data, you
can read database.

3.2.3 READING DATABASE
Now you have pointer to data, number of fields, types and sizes.
Just get this page.
You can get 3 types of records:
a) pointer to data
b) data
c) mixed (only part of data and pointer to rest of data)
And of course you must be prepared to read all these types...
[to be continued]

3.2.4 FIELD TYPES
These types are defined in Database.h from Z88DK.
DB_INT8		1  (01)
DB_INT16	2  (02)
DB_INT32	3  (03)
DB_FXDSTR	11 (0B)
DB_FXDDAT	12 (0C)
DB_VARSTR	21 (15)
DB_VARDAT	22 (16)
DB_RECID	90 (5A)
 
3.2.5 DATABASE NUMBERS
(see export database from RexToolsBeta and Database.h from Z88DK)
DBID_UNKNOWN = 0 (0000)
DBID_COMMONSEARCHHISTORY = 120 (0078)
DBID_SHELLADDIN = 150 (0096)
DBID_SETUPINFO = 160 (00A0)
DBID_DEVICEID = 170 (00AA)
DBID_ADDRESS = 1000 (03E8)
DBID_CALENDAR = 2000 (07D0)
DBID_TODO = 3000 (0BB8)
DBID_MEMO = 4000 (0FA0)
DBID_MAIL = 5000 (1388)
DBID_DICTIONARY = 7000 (1B58)
DBID_CLOCK = 8000 (1F40)
DBID_PICTURE = 10000 (2710)
my additions:
DBID_ADDRESS_CATEGORIES = 1002 (03EA)


4. WHAT IS NEEDED
a) meaning of unknown fields
b) testing
...