ports
Submitted by
on
https://www.mail-archive.com/sam-users@nvg.ntnu.no.backup/msg03859.html
Fixed alignment (sort of):
General port map - Read
-----------------------
+------------------------------------------------------------------+
|PORT (RD)|128--7| 64--6| 32--5| 16--4| 8--3| 4--2| 2--1| 1--0|
+----+----------+------+------+------+------+------+------+------+------+---+
| FF|ATTRIBUTES|FLASH |BRIGHT|G PAPR|R PAPR|B PAPR|G INK|R INK|B INK|255|
|----+----------+------+------+------+------+------+------+------+------+---|
| FE|KEYBOARD |SOFF |EAR |SPEN |KEY 5|KEY 4|KEY 3|KEY 2|KEY 1|254|
|----+----------+------+------+------+------+------+------+------+------+---|
|FFFE|RDMSEL |SOFF |EAR |SPEN |RIGHT |LEFT |DOWN |UP |CNTRL |254|
|----+----------+-------------------------------------------------------+---|
| FD|MIDI-IN | 8 BITS DATA |253|
|----+----------+-------------------------------------------------------+---|
| FC|VMPR |RXMIDI|MODE 1|MODE 0|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|252|
|----+----------+------+------+------+------+------+------+------+------+---|
| FB|HMPR |MCNTRL|MD3 S1|MD3 S0|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|251|
|----+----------+------+------+------+------+------+------+------+------+---|
| FA|LMPR |WPROT |ROM 1|RAM 0|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|250|
|----+----------+------+------+------+------+------+------+------+------+---|
| F9|STATUS |KEY 8|KEY 7|KEY 6|MIDI O|FRAME |MIDI I|COMMS |LINE |249|
|----+----------+-------------------------------------------------------+---|
|01F8|HPEN | CURRENT YSCAN VALUE |248|
|----+----------+-------------------------------------------------------| |
|00F8|LPEN | CURRENT XSCAN VALUE DIV 4 |TXFMST|BLUE 0| |
|----+----------+-------------------------------------------------------+---|
| F0|DISC 2 | DRIVE 2 BASE PORT - SEE BELOW |240|
|----+----------+-------------------------------------------------------+---|
| EF|SAMBUS CLK| BATTERY BACKED REALTIME CLOCK - SEE BELOW |239|
|----+----------+-------------------------------------------------------+---|
| EC|COMMS IFC | COMMS I/FACE SERIAL CHIP (IM26C91) -- SEE BELOW |236|
|----+----------+-------------------------------------------------------+---|
| E9|PTR STATUS| | | | | | | |BUSY |233|
|----+----------+-------------------------------------------------------+---|
| E0|DISC 1 | DRIVE 1 BASE PORT - SEE BELOW |224|
|----+----------+-------------------------------------------------------+---|
| DF|MULTIROM D|MR_OFF|MR_RAM|PAGE 5|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|223|
|----+----------+------+------+------+------+------+------+------+------+---|
| DE|MULTIROM A|MR_OFF|MR_RAM|PAGE 5|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|222|
|----+----------+-------------------------------------------------------+---|
| D0|ENTROPY | ENTROPY PORTS ALLOCATED -- PORTS &xxD0 TO &xxDF |208|
|----+----------+-------------------------------------------------------+---|
| 7F|BLUE ALPHA| BLUE ALPHA PORTS ALLOCATED -- PORTS &007F TO &FF7F |127|
+---------------------------------------------------------------------------+
General port map - Write
------------------------
+------------------------------------------------------------------+
|PORT (WR)|128--7| 64--6| 32--5| 16--4| 8--3| 4--2| 2--1| 1--0|
+----+----------+------+------+------+------+------+------+------+------+---+
|01FF|SOUND ADDR| | | |ADDR 4|ADDR 3|ADDR 2|ADDR 1|ADDR 0|255|
|----+----------+-------------------------------------------------------| |
|00FF|SOUND DATA| 8 BITS DATA | |
|----+----------+-------------------------------------------------------+---|
| FE|BORDER |SOFF |THROM |VID&08|BEEP |MIC |VID&04|VID&02|VID&01|254|
|----+----------+-------------------------------------------------------+---|
| FD|MIDI-OUT | 8 BITS DATA |253|
|----+----------+-------------------------------------------------------+---|
| FC|VMPR |TXMIDI|MODE 1|MODE 0|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|252|
|----+----------+------+------+------+------+------+------+------+------+---|
| FB|HMPR |MCNTRL|MD3 S1|MD3 S0|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|251|
|----+----------+------+------+------+------+------+------+------+------+---|
| FA|LMPR |WPROT |ROM 1|RAM 0|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|250|
|----+----------+-------------------------------------------------------+---|
| F9|LINE INT | YSCAN LINE TO INTERRUPT ON |249|
|----+----------+-------------------------------------------------------+---|
| F8|CLUT | |GRN 1|RED 1|BLU 1|HALFBR|GRN 0|RED 0|BLU 0|248|
|----+----------+-------------------------------------------------------+---|
| F0|DISC 2 | DRIVE 2 BASE PORT - SEE BELOW |240|
|----+----------+-------------------------------------------------------+---|
| EF|SAMBUS CLK| BATTERY BACKED REALTIME CLOCK - SEE BELOW |239|
|----+----------+-------------------------------------------------------+---|
| EE|ACCELERATR| |CLKSPD|IORQW |ASWAIT|BANK D|BANK C|BANK B|BANK A|238|
|----+----------+-------------------------------------------------------+---|
| EC|COMMS IFC | COMMS I/FACE SERIAL CHIP (IM26C91) -- SEE BELOW |236|
|----+----------+-------------------------------------------------------+---|
| E9|PTR CTRL | | | | | | | |STROBE|233|
|----+----------+-------------------------------------------------------+---|
| E8|PTR DATA | 8 BITS DATA |233|
|----+----------+-------------------------------------------------------+---|
| E0|DISC 1 | DRIVE 1 BASE PORT - SEE BELOW |224|
|----+----------+-------------------------------------------------------+---|
| DF|MULTIROM D|MR_OFF|MR_RAM|PAGE 5|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|223|
|----+----------+------+------+------+------+------+------+------+------+---|
| DE|MULTIROM A|MR_OFF|MR_RAM|PAGE 5|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|222|
|----+----------+-------------------------------------------------------+---|
| D0|ENTROPY | ENTROPY PORTS ALLOCATED -- PORTS &xxD0 TO &xxDF |208|
|----+----------+-------------------------------------------------------+---|
| 83|MEGHIGH D|PAGE15|PAGE14|PAGE13|PAGE12|PAGE11|PAGE10|PAGE 9|PAGE 8|131|
|----+----------+------+------+------+------+------+------+------+------+---|
| 82|MEGHIGH C|PAGE15|PAGE14|PAGE13|PAGE12|PAGE11|PAGE10|PAGE 9|PAGE 8|130|
|----+----------+------+------+------+------+------+------+------+------+---|
| 81|MEGLOW D|PAGE 7|PAGE 6|PAGE 5|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|129|
|----+----------+------+------+------+------+------+------+------+------+---|
| 80|MEGLOW C|PAGE 7|PAGE 6|PAGE 5|PAGE 4|PAGE 3|PAGE 2|PAGE 1|PAGE 0|128|
|----+----------+-------------------------------------------------------+---|
| 7F|BLUE ALPHA| BLUE ALPHA PORTS ALLOCATED -- PORTS &007F TO &FF7F |127|
+---------------------------------------------------------------------------+
Keyboard matrix / port allocations
----------------------------------
+-----------------------------------------------+
| 7 | 6 | 5 | BASE PORT &F9/249 |
+-----------+-----------------+-----------------------------|
|ADRSELECTOR|BASE PORT &FE/254| 4 | 3 | 2 | 1 | 0 |
|-----------+-----------------+-----+-----+-----+-----+-----|
|11111110|FE| F 3 | F 2 | F 1 | V | C | X | Z |SHIFT|
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|11111101|FD| F 6 | F 5 | F 4 | G | F | D | S | A |
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|11111011|FB| F 9 | F 8 | F 7 | T | R | E | W | Q |
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|11110111|F7| CAPS| TAB | ESC | 5 | 4 | 3 | 2 | 1 |
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|11101111|EF|DELET| + | - | 6 | 7 | 8 | 9 | 0 |
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|11011111|DF| F 0 | " | = | Y | U | I | O | P |
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|10111111|C0| EDIT| : | ; | H | J | K | L |RETRN|
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|01111111|7F| INV | . | , | B | N | M | SYM |SPACE|
|--------+--+-----+-----+-----+-----+-----+-----+-----+-----|
|11111111|FF| | | |RIGHT| LEFT| UP| DOWN|CNTRL|
+-----------------------------------------------------------+
Disc controller port allocations
--------------------------------
+-----------------------------------------------+
| SIDE1 | DISC CONTROLLER | SIDE2 |
|-------------+-------------------+-------------|
|DISC 1|DISC 2| READ | WRITE |DISC 1|DISC 2|
|------+------+---------+---------+------+------|
| E0 | F0 | STATUS | COMMAND | E4 | F4 |
|------+------+---------+---------+------+------|
| E1 | F1 | TRACK | TRACK | E5 | F5 |
|------+------+---------+---------+------+------|
| E2 | F2 | SECTOR | SECTOR | E6 | F6 |
|------+------+---------+---------+------+------|
| E3 | F3 | DATA | DATA | E7 | F7 |
+-----------------------------------------------+
SAMbus Realtime clock port allocations
--------------------------------------
+-------------------------------------+
|PORT (R/W)| Bits 3-0 |RANGE|
+----+-----------+-------------------+-----+-----+
|00EF|SECONDS LSD|S 8|S 4|S 2|S 1| 0-9 | 239|
|----+-----------+----+----+----+----+-----+-----|
|10EF|SECONDS MSD| |S 40|S 20|S 10| 0-5 | 4335|
|----+-----------+----+----+----+----+-----+-----|
|20EF|MINUTES LSD|M 8|M 4|M 2|M 1| 0-9 | 8431|
|----+-----------+----+----+----+----+-----+-----|
|30EF|MINUTES MS | |M 40|M 20|M 10| 0-5 |12527|
|----+-----------+----+----+----+----+-----+-----|
|40EF|HOURS LSD|H 8|H 4|H 2|H 1| 0-9 |16623|
|----+-----------+----+----+----+----+-----+-----|
|50EF|HOURS MSD| | |H 20|H 10| 0-2 |20719|
|----+-----------+----+----+----+----+-----+-----|
|60EF|DAY LSD|D 8|D 4|D 2|D 1| 0-9 |24815|
|----+-----------+----+----+----+----+-----+-----|
|70EF|DAY MSD| | |D 20|D 10| 0-3 |28911|
|----+-----------+----+----+----+----+-----+-----|
|80EF|MONTH LSD|MO 8|MO 4|MO 2|MO 1| 0-9 |33007|
|----+-----------+----+----+----+----+-----+-----|
|90EF|MONTH LSD| | | |MO10| 0-1 |37103|
|----+-----------+----+----+----+----+-----+-----|
|A0EF|YEAR LSD|Y 8|Y 4|Y 2|Y 1| 0-9 |41199|
|----+-----------+----+----+----+----+-----+-----|
|B0EF|YEAR MSD|Y 80|Y 40|Y 20|Y 10| 0-9 |45295|
|----+-----------+----+----+----+----+-----+-----|
|C0EF|WEEK DAY *| |W 4|W 2|W 1| 0-6 |49391|
|----+-----------+----+----+----+----+-----+-----|
|D0EF|CONTROL D| | |BUSY|HOLD| |53487|
|----+-----------+----+----+----+----| |-----|
|E0EF|CONTROL E| | | | | N/A |57583|
|----+-----------+----+----+----+----| |-----|
|F0EF|CONTROL F| | | | | |61679|
+------------------------------------------------+
* Week day: 0 = Sunday, 1 = Monday, ... 6 = Saturday
LSD -- Least Significant Digit
MSD -- Most Significant Digit
Bits 7-4: don't care.
Serial Communications Interface ports (IM26C91 UART)
----------------------------------------------------
+-----------------------------------------------------------------+
|PORT (WR)|128--7| 64--6| 32--5| 16--4| 8--3| 4--2| 2--1| 1--0|
+----+---------+------+------+------+-------------+------+-------------+----+
|00EC| MR1 |RXRTS |R/INT |ERRORM|PARITY MODE|PARTYP|BITS PER CHAR| 236|
| |---------+-------------+------+----------------------------------| |
| | MR2 |CHANNEL MODE|TXRTS |CTSETX| STOP BIT LENGTH | |
|----+---------+-------------+------+------+---------------------------+----|
|01EC| SR |RBREAK|FRAERR|PARERR|OVRERR|TXEMT |TXRDY |FFULL |RXRDY | 492|
|----+---------+-------------------------------------------------------+----|
|02EC|RESERVED*| DO NOT READ | 748|
|----+---------+-------------------------------------------------------+----|
|03EC| RHR | RECEIVER HOLDING REGISTER (8 BITS DATA) |1004|
|----+---------+-------------------------------------------------------+----|
|04EC|RESERVED*| DO NOT READ |1260|
|----+---------+-------------------------------------------------------+----|
|05EC| ISR |MP1PCH|MP1PCS| |CNTRDY|DBREAK|RXRDYF|TXEMT |TXRDY |1516|
|----+---------+------+------+------+------+------+------+------+------+----|
|06EC| CTU |C/T 15|C/T 14|C/T 13|C/T 12|C/T 11|C/T 10|C/T 9|C/T 8|1772|
|----+---------+------+------+------+------+------+------+------+------+----|
|07EC| (CTL) |C/T 7|C/T 6|C/T 5|C/T 4|C/T 3|C/T 2|C/T 1|C/T 0|2028|
+---------------------------------------------------------------------------+
* Reserved registers should never be read during normal operation
since they
are reserved for internal diagnostics.
+-----------------------------------------------------------------+
|PORT (WR)|128--7| 64--6| 32--5| 16--4| 8--3| 4--2| 2--1| 1--0|
+----+---------+------+------+------+-------------+------+-------------+----+
|00EC| MR1 |RXRTS |R/INT |ERRORM|PARITY MODE|PARTYP|BITS PER CHAR| 236|
| |---------+-------------+------+----------------------------------| |
| | MR2 |CHANNEL MODE|TXRTS |CTSETX| STOP BIT LENGTH | |
|----+---------+---------------------------+---------------------------+----|
|01EC| CSR | RECEIVER CLOCK SELECT | TRANSMITTER CLOCK SELECT | 492|
|----+---------+---------------------------+---------------------------+----|
|02EC| CR | MISCELLANEOUS COMMANDS |DIS TX|ENA TX|DIS RX|ENA TX| 748|
|----+---------+-------------------------------------------------------+----|
|03EC| THR | TRANSMITTER HOLDING REGISTER (8 BITS DATA) |1004|
|----+---------+-------------------------------------------------------+----|
|04EC| ACR |BRGSET|CNTR/TIMER MODE/SRCE|POWERD|MP0 PIN FUNCTION SEL|1260|
|----+---------+------+--------------------+------+--------------------+----|
|05EC| IMR |MP1CI |MP1CL | |CNTRDY|DBREAK|RXRDYF|TXEMTI|TXRDYI|1516|
|----+---------+------+------+------+------+------+------+------+------+----|
|06EC| CTUR |C/T 15|C/T 14|C/T 13|C/T 12|C/T 11|C/T 10|C/T 9|C/T 8|1772|
|----+---------+------+------+------+------+------+------+------+------+----|
|07EC| CTLR |C/T 7|C/T 6|C/T 5|C/T 4|C/T 3|C/T 2|C/T 1|C/T 0|2028|
+---------------------------------------------------------------------------+
Third Party vendor port allocation
----------------------------------
ENTROPY
-------
&xxEE Accelerator WRITE ONLY
&xxDF &xxDE MultiROM WRITE ONLY
&xx82 &xx83 Gig Memory Expansion WRITE ONLY
&xxD0 -> &xxDF Reserved for future expansion
BLUE ALPHA
----------
&FF7F Voicebox UNKNOWN
&7C7F -> &7F7F Sampler UNKNOWN
Kaleidoscope WRITE ONLY
Hardware Kit READ/WRITE
&xx7F Reserved for future expansion
Back Panel Help Sheet
---------------------
+----------------------------------------------------------------------------
| NMI MIDI OUT MIDI IN JOYSTICK MOUSE RESET EXPANSION CONNECTOR
|
|
| 7. .6 7. .6 1 2 3 4 5 7. .6
| . . . . . 8 +-------------------
| +-+ 3. .1 3. .1 3. . .1 +-+ |.. 1C
| +-+ . . . . +-+ |.. 1A
| 5. .4 5. .4 6 7 8 9 5. .4 +-------------------
| . . .
| 2 2 2
+----------------------------------------------------------------------------
----------------------------------------------------------------------------+
EXPANSION CONNECTOR EAR/MIC LIGHT ON/OFF SAM SCART POWER |
PEN |
+--------------+ |
20|.. 4..|2 |
--------------------+ | | |
32C..| ++ 3. .1 +--+ | | 3. 6 .1 |
32A..| ++ +--+ ++.. 3..|1 . |
--------------------+ 5. .4 21++19 | . .4 |
. +------------+ 5 . |
2 2 |
----------------------------------------------------------------------------+
MIDI IN MIDI OUT ATARI JOYSTICK MOUSE
------- -------- -------------- -----
1 Net - Loop 1 Net - Loop 1 Up 1 Down
2 NC 2 GND 2 Down 2 Up
3 Net + Loop 3 Net + Loop 3 Left 3 CTRL
4 Midi + In 4 Midi + Out 4 Right 4 Left
5 Midi - In 5 Midi - Out 5 0v 5 Right
6 Net - Loop 6 Net - Loop 6 Fire 6 Interrupt
7 Net + Loop 7 Net + Loop 7 +5v 7 RDMSEL
8 STROBE1 (active high) 8 +5v
9 STROBE2 (active high) Screen - Ground
LIGHT PEN SAM SCART POWER INPUT
--------- --------- -----------
1 +5v 1 Audio RH out 13 Red Earth 1 +5v
2 Audio LH O/P 2 SPEN in 14 CSYNC Earth 2 0v (Signal GND)
3 0v 3 Audio LH out 15 Red Lin out 3 0v (Digital GND)
4 SPEN input 4 Audio Earth 16 CSYNC 4 Composite Vid O/P
5 Audio RH O/P 5 Blue Earth 17 Comp. Video Earth 5 +12v
6 Blue TTL out 18 +12v Power in 6 Sound Ouput (Mono)
7 Blue Lin out 19 Comp. Video out
8 Red TTL out 20 Bright TTL out
9 Green Earth 21 GND
10 Green TTL out
11 Green Lin out
12 +5v Power in
EXPANSION CONNECTOR DETAILS
---------------------------
+-------------------------------------------------------------+
Pin 1C |++ ++|Pin 32C
|++ ++|
|++ ++|
Pin 1A |++ ++|Pin 32A
+-------------------------------------------------------------+
Standard 64 pin Euroconnector socket with rows A-C fitted. All identifiers
ending with L are active low.
PIN SIGNAL PIN SIGNAL
--- ------ --- ------
1A DBDIRL 1C IORQL
2A RDL 2C MREQL
3A WRL 3C HALTL
4A BUSACKL 4C NMIL
5A WAITL 5C INTLL
6A BUSREQL 6C CD1
7A RESETL 7C CD0
8A CM1L 8C CD7
9A REFRESHL 9C CD2
10A 0 VOLTS* 10C +5 VOLTS*
11A A0 11C CD6
12A A1 12C CD5
13A A2 13C CD3
14A A3 14C CD4
15A A4 15C CPU CLK
16A A5 16C A15
17A A6 17C A14
18A A7 18C A13
19A A8 19C A12
20A A9 20C A11
21A A10 21C DISC 2L
22A EXTINTL 22C ROMCSL
23A XMEML 23C EARMIC
24A 8 MHz 24C DISC 1L
25A RED 1 25C PRINTL
26A GREEN 1 26C BLUE 1
27A CSYNCL 27C ROMCSRL
28A SPEN 28C AUDIO RIGHT OUTPUT
29A BLUE 0 29C AUDIO LEFT OUTPUT
30A RED 0 30C COMPOSITE VIDEO
31A BRIGHT 31C GREEN 0
32A +5 VOLTS 32C 0 VOLTS
*Not to be used as a supply rail - reference only
MEMORY MAPPING
--------------
+-------------------------------------------------------+
|<------------ 64k ADDRESSING SPACE OF CPU ------------>|
| |
|0000 3FFF|4000 7FFF|8000 BFFF|C000 FFFF|
+-------------+-------------+-------------+-------------|
| | | | |
RAM 0 = 0| | SECTION B | SECTION C | SECTION D | ROM 1 = 0
| ROM 0 | | | |
| | LMPR +1 | HMPR | HMPR +1 | MCNTRL = 0
| | | | |
+-------------------------------------------------------+
| | | | |
| | | | |
+-------------+ +-------------+
| | | | |
RAM 0 = 1| SECTION A | | | ROM 1
| | | | ROM 1 | = 1
(LMPR) | LMPR | | | (LMPR)
| | | | |
+-------------+ +-------------+
| | |
| | |
+---------------------------+
| | |
| EXTERNAL | EXTERNAL | MCNTRL
| | | = 1
| MEMORY C | MEMORY D | (HMPR)
| | |
+---------------------------+
If the ENTROPY MultiROM expansion is connected, then ROM 0 and ROM 1 may be
replaced with other data. These are controlled by ports &DE and &DF;
&DE handles ROM 0, &DF handles ROM 1.
MR_OFF = 1 MR_OFF = 0
+-------------+ +-------------+
| | | |
| ORIGINAL | | MULTI-ROM |
| |---| | MR_RAM = 0
| ROM 0/1 | | | ROM PAGE |
| | | | |
+-------------+ | +-------------+
|
| +-------------+
| | |
| | MULTI-ROM |
+-| | MR_RAM = 1
| RAM PAGE |
| |
+-------------+
ENTROPY MULTI-ROM
-----------------
The Entropy Multi-ROM (M-R) expansion board has been designed as a
multi-function programmer's toolkit. Its 128k-512k ROM contains a fast
Macro/Conditional Assembler, Monitor & Debugger, Systems Utilities,
Disc Toolkit and other programs.
The Entropy Multi-ROM is accessed by two ports, &DE and &DF. When ROM is
paged into sections A or D, it may be overlayed with the M-R's RAM orROM.
On reset, registers &DE and &DF are reset to contain zero. This pages in the
M-R's initialisation code. On power-up, the SAM's memory is tested and
initialised; on reset, the full initialisation procedure is not followed,
allowing the memory to be examined or debugged.
MultiROM Specifications
-----------------------
ROM: between 128k and 512k system ROM, including BIOS, initialisation
routines, modified SAM Basic ROM v3.0, SAMDOS, toolkit, Assembler etc.
RAM: Either 32k or 128k of battery-backed static RAM.
Multi-ROM Memory Map << THIS INFORMATION MAY NOW BE
-------------------- << INCORRECT!
MultiROM system variables begin in RAM page 1 at &2000. They should not be
overwritten, as the M-R uses them as part of its configuration.
MultiROM pages 0 and 1 are also used as a temporary 24k buffer. This is so
that the M-R may display a screen without destroying data.
On a 512k machine, page 30 of the SAM's internal RAM is copied to page 0 of
the M-R's RAM. Page 31 (&0000-&1FFF) is copied into the corresponding area
of page 1 of the M-R RAM.
On a 256k machine, page 14 is copied to page 0 of the M-R, and page 15 is
copied to page 1.
+-------------------------+
| |
| BUFFER/SCRATCHPAD AREA | PAGE 0
| |
+-------------------------|
| BUFFER/SCRATCHPAD AREA |
| - - - - - - - - - - - - | PAGE 1
| Multi-ROM SYSTEM VARS |
+-------------------------|
| | Multi-ROM Application PAGES
| | (IF PRESENT)
| Space | 2-->7
+-------------------------+
Multi-ROM Systems Variables <<THIS INFORMATION MAY NOW BE
--------------------------- << INCORRECT
All of the Multi-ROM systems variables reside in page 1 of the Multi-ROM's
RAM. If they are paged into section A, use the addresses below as given; if
however they are paged into section D, add &C000 to them.
ADDRESS
&2000 (9) MALLOCT MultiROM's RAM Allocation Table
&2009 (257) XALLOCT External memory pages &0000 to &00FF Allocation table
(Used in conjunction with MasterDOS / EDOS)
&2110 (32) GALLOCT Gigabyte allocation table (bitwise)
&2130 (1) SYSDAT BIT 0 -- SAM Basic has been initialised if set
1 -- External memory is present if set
2 -- Internal memory physically present:
0 -- 256k 1 -- 512k
3-4 -- Number of physical drives present
5 -- Gig is present if set
6 -- SAM Basic area is invalid if set (may be done
for more source space, by the monitor prog,
etc)
7 -- Memory fault has occured if set
Multi-ROM Allocation tables
---------------------------
These act exactly as in the ALLOCT table held at &5100 in the SAM's internal
memory, and are used in the same way, except for the GALLOCT table.
GALLOCT is the Gigabyte allocation table. It is an array of bits; each bit
corresponds to a 4Mb section of external memory. If it is present, the bit
is set, if it is not, it is reset. This is to aid quick allocation of memory.
If more than 4Mb of external memory is present, then the first pages of the
second 4Mb section will be filled with an XALLOCT table, 65280 bytes in
length. This contains a byte for each possible external memory page (other
than the first 256 pages, which are catered for by the other XALLOCT table).
Allocation table values
-----------------------
FF -- Page not present
FE -- Memory fault in this page -- do not use to store data
D0 -- DOS
C1 -- METEOR assembler
C0 -- COMET assembler
B0 -- BASIC
20 -- Utility page
The correct way to allocate memory pages to your programs is to request it
using the MEM_ALLOC system call in the MultiROM, or an equivalent program.
This will return a unique ID byte for your program to use in the allocation
table.
The MultiROM information in this documentation is now a little out of date -
it is recommended that you look at the latest information release instead,
although some of the points raised here are still valid.