!!! All you ever wanted to know about: Atari Cartridges
[{TableOfContents }]
This is a big collection of info-texts, that all deal with Atari cartridges. Allthough I did not write any of these texts, I collected them and now present them here for you. There are four different texts in total, thus you can read four different parts - ranging from general information (RAM/ROM control) to more and more specific information and finally some programming hints (and source!) on how to convert game files into Atari cartridges...
!!! PART 1 RAM/ROM Control On An XL/XE Computer
by John Picken
!! AUXILIARY ROM CONTROL
Program control of Atari BASIC, OSS Super Cartridges, the R-Time 8
cartridge and, in a limited fashion, SpartaDOS X, is fairly simple
but for one fact: there's nearly no documentation available on the
subject. What I present here is gleaned from a bit of disassembly
and a lot of experimentation (pretentious word for "try it until it
don't crash").
Note that all following references to a cartridge being "present"
imply that it is turned on if it's plugged in but turned off,
consider it "absent". You may always consider the RT8 to be absent
unless you're actually trying to access it. First let's look at the
addresses used for, or in conjunction with, auxiliary ROM/RAM
control. PORTB has already been covered; just keep in mind the function of
the BASIC bit.
BASICF is a flag in low memory to tell the OS, on system reset, how
to set bit 1 of PORTB. If this flag contains any non-zero value
the BASIC ROM will be disabled.
TRIG3 is an address on the GTIA chip which was used for joystick
trigger #3 on the 400/800. On the XL/XE it is a cartridge status
indicator; if a cartridge is present it reads 1, otherwise it will
be 0. There is no other possible reading at this address.
GINTLK is set, on boot, by the OS and is a copy of TRIG3. The OS
compares GINTLK with TRIG3 during the deferred vertical blank
interrupt and, if the two don't match, goes into a "soft" lockup
(i.e. a reset will re-boot).
CARTCK holds a checksum, calculated on boot, by the OS. On a reset,
if a cartridge is present as signalled by TRIG3, the OS
re-calculates the sum and compares it with CARTCK. If the two don't
match, the OS assumes you've pulled or inserted a cartridge and
immediately re-boots. Note that Mapping the Atari is vague on this:
it applies to all XL/XE's, not just the 1200.
CARTCK, TRIG3 and GINTLK are effective for all cartridges except
(in part) the RT8. One other important thing to note is that the
TRIG3/GINTLK comparison occurs during the deferred vertical blank.
This means you can barl around with a cartridge to your heart's
content as long as the stage two vblank doesn't occur and you don't
hit Reset. You can prohibit vblank2 in any of three ways: disable
all NMI's, set CRITIC to a non-zero value or, most simply, use a
SEI opcode.
The hardware address range for all cartridge control is
$D500-$D5FF. Within that page, OSS cartridges use $D500-$D50F, the
CSS MUX OS uses $D570-$D57F, the RT8 uses $D5B8-$D5B9, and SDX uses
$D5E0-$D5EF. This sounds straightforward; unfortunately it isn't.
!! Atari-type Cartridges
I made no mention of Atari cartridges in the address ranges because
once you stick one of the beasts into the slot, your only control
over it comes with the power switch or by using SDX. An Atari
cartridge can not be turned off by software unless SDX is present
(even if turned off). SDX can control one because it sits between
the computer and the cartridge and can, thereby, zap it
electronically. However, the foregoing discussion of TRIG3 and
GINTLK remains fully applicable.
!! OSS Super Cartridges
Though the control range is $D500 to $D50F, the cartridge address
decode logic is only four bits wide. This means that any access
(read from, write to, or otherwise manipulate) a $D5xy address
affects the cartridge which ignores the "x". OSS cartridges react
to the whole $D500 page based on the low four bits of the address.
To enable an OSS cartridge bank, add the bank number to $D500 and
access that address (i.e. for bank n, STA $D50n, LDA $D50n, STA
$D500,X where the x register holds n, etc.) In theory, a cartridge
should be able to contain up to sixteen 8k banks and still allow
you to turn it off. In practice, they contain two or three
switchable 4k banks and one "master" 4k bank.
For OSS cartridges, the ROM bank number is found at location $AFFF.
Valid values at $AFFF are 0, 3 and 4 for Action! and 0, 1 and 9 for
MAC/65. Other bank values produce varying results. MAC/65 ignores
bits 1 and 2 so any value from 0 to 7 results in selection of
either the odd or even bank. With Action! attempts to select other
bank numbers result in selection of one of the real ones or in
selection of nothing i.e. a monitor shows a pile of $AF's in the
$AF page just as when you examine page $D7 and get $D7 at all
addresses. BASIC XE has banks 0, 1 and 9 but bank 9 is RAM. In bank
9, the BXE cartridge is off but TRIG3 stays high; a sneaky way to
avoid having to worry about GINTLK while using the RAM under the
cartridge.
There are two constants for cartridges: Addressing bit 3 alone
turns cartridge ROM off and, bank 0 is the bank in which the
cartridge boots and initializes. Here are "maps" of the banks in
two cartridges:
MAC/65
{{{
0123456789ABCDEF: Bank Selection
rrrrrrrr r r r r: r=rom, empty=ram
01010101 9 9 9 9: bank #
01 9 : valid rom banks
}}}
Action!
{{{
0123456789ABCDEF: Bank Selection
rrrrrr r : r=rom, empty=ram
000340 3 : bank #
0 34 : valid rom banks
}}}
! OSS Cartridge Examples
Following are several examples of cartridge and BASIC control with
SDX not present. I'll start with equates for all examples from
Mapping the Atari (XL edition):
{{{
WARMST = $08
BOOT? = $09
CRITIC = $42
RAMTOP = $6A
COLDST = $0244
CARTCK = $03E8
BASICF = $03F8
GINTLK = $03FA
TRIG3 = $D013
PORTB = $D301
NMIEN = $D40E
EDITRV = $E400
}}}
Here's the simplest: turn off a cartridge and enable BASIC assuming
both are actually present.
{{{
SEI Kill stage 2 vblank
STA $D508 Kill any cartridge
LDA PORTB
AND #$FD Drop basic bit
STA PORTB
LDA TRIG3 This should be 0
STA BASICF Flag it and
STA GINTLK correct the cart shadow
CLI Enable stage 2 vblank
}}}
Now let's access RAM under a cartridge:
{{{
SEI Kill stage 2 vblank
LDA PORTB
PHA Save Portb
ORA #$02 Kill basic rom
STA PORTB
LDA #$08 Assume no cartridge.
LDX TRIG3 Check assumption.
BEQ GOTBNK Go if none or off,
LDA $AFFF else get the bank
GOTBNK
PHA Save cartridge bank.
STA $D508 Kill any OSS cartridge
LDA TRIG3 Set the shadow before
STA GINTLK the stage 2 vblank!
CLI Enable stage 2 vblank
}}}
Do whatever in the RAM, then restore the previous status:
{{{
SEI Kill stage 2 vblank
PLA Recover cartridge bank
TAX and restore the cart
STA $D500,X to it's prior status
LDA TRIG3 Reset Gintlk to
STA GINTLK correct status
PLA Restore prior Basic
STA PORTB rom status
CLI Enable stage 2 vblank
}}}
Just turning a cartridge off is simple:
{{{
SEI Kill vblank 2
STA $D508
LDA TRIG3 Make sure it went
STA GINTLK off and flag it
CLI Enable stage 2 vblank
}}}
Cold-starting an OSS cartridge is only slightly more complex:
{{{
SEI Kill vblank 2
STA $D500 Enable cart bank 0
LDA TRIG3 Set the shadow
STA GINTLK correctly
LDA PORTB
PHA
ORA #$01
STA PORTB Ensure OS is on
CLC Calculate the
LDX #0 checksum
TXA for reset.
CSLOOP
ADC $BFF0,X Note the sum
INX includes the
BNE CSLOOP first 240 bytes
STA CARTCK of the OS ROM.
PLA Restore any RAM
STA PORTB OS (or Sparta)
CLI Enable stage 2
}}}
After cold-starting an OSS cartridge or BASIC, set WARMST to 0 to
flag a boot so that the buffer pointers are cleared (if you don't,
you can, for example enter BASIC, type LIST and get an endless
display of zeros and/or a lockup). Then initialize the ROM. With
Action! and BASIC this doesn't matter as the initialization
routines just RTS; with BASIC XE I'm not sure; with MAC/65 it's
required. To initialize any cartridge:
{{{
LDX #$FF Say we're on a boot
STX COLDST and make sure all
INX flags reflect this
STX WARMST
INX
STX BOOT?
JSR INIT Go do it
LDX #$FF Say we're back to
STX WARMST normal status, i.e.
INX what happens on Reset.
STX COLDST Note that some or all
INX carts play with some
STX BOOT? of these flags!
RTS
INIT
JMP ($BFFE) Cartridge init vector
}}}
After enabling or disabling a cartridge or BASIC, you also have to
ensure top of RAM and screen pointers are correct. To do this,
execute a "GRAPHICS 0". In machine language terms, you set RAMTOP
and then close and re-open channel 0 to the "E:" device. You can do
this in the traditional manner via CIOV or more simply by calling
the following subroutine with the accumulator holding $C0 if
turning ROM off and $A0 if turning it on.
{{{
GRAPH0
STA RAMTOP Either $A0 or $C0
LDX #0 Indicate channel 0
LDY #2 Point to Close vector
JSR EDO
LDY #0 and now to Open vector
EDO
LDA EDITRV+1,Y
PHA
LDA EDITRV,Y
PHA
RTS
}}}
Be aware that turning off BASIC XE does not free up the RAM under
the cartridge if you intend to later restore the cartridge. BXE
uses that RAM as well as that under the OS floating point routines
and also (undocumented) sets an interrupt vector in the last page
of RAM ($FFFx).
One final note on turning ROM off or on: following the Graphics 0,
an RTS under Sparta will usually lock up the keyboard requiring a
reset. Sparta installs its own E: handler so when you use the OS
handler to reopen E: Sparta's vectors are no longer valid. The
simple way around this is to exit via a JMP (DOSVEC). This is
probably a good idea with any command-processor FMS where you can
use a batch file instead of an autorun to set things up.
!! The SpartaDOS X Cartridge
SDX boots in bank 0 but normally works in bank 1 with one
subroutine call back to bank 0 via low RAM which I suspect is used
to load files from CAR: The cartridge contains eight different ROM
banks (0 to 7), but I have not discovered any single location
containing a bank identifier and I doubt there is one as its
existence essentially would mean a "hole" in the middle of each
ROMdisk bank. The control address for the X cartridge is $D5E0 used
similarly to $D500 with an OSS cartridge.
The following code will leave the currently selected bank in the Y
register with version 4.20. With other versions, you're on your
own.
{{{
LDA $A004
LDY #7
LOOP
CMP XBANK,Y
BEQ GOTIT
DEY
BPL LOOP
LDY #$01 Can't figure, make it 1
GOTIT
RTS
XBANK
.BYTE $32,$1F,$02,$1D
.BYTE $D4,$1C,$61,$56
}}}
The ROMdisk directory is at the beginning of bank 2 and follows
normal Sparta format except that the address of the first sector
map is the actual starting location in ROM of the stored program.
The first two entries look like this:
{{{
.BYTE $08 Status: In use
.WORD 16384 Start: Bank 2 Offset 0
.WORD 598 Length
.BYTE 0 Length (high byte)
.BYTE "MAIN "
.BYTE 1,1,70 Date
.BYTE 251,0,0 Time
;
.BYTE $08 Status: In use
.WORD 16982 Start: Bank 2 Offset 598
.WORD 7288 Length
.BYTE 0 Length (high byte)
.BYTE "SPARTA SYS"
.BYTE 6,2,89 Date
.BYTE 15,28,40 Time
;
}}}
To convert the starting address to a bank and offset within the
bank:
{{{
bank = int(address/$2000) and
offset = address-$2000*bank
}}}
CAR.COM uses the following combinations to control all three ROMs
in the cartridge area. The values under "SDX" and "OSS" are offsets
from $D5E0 and $D500 respectively and those under BAS are the value
in bit 1 of PORTB. The "on" under the OSS column is the value found
at $AFFF before the cartridge was last turned off and used to
reenable it. The $0C value for SDX is what causes it to latch any
cartridge off and the $08 makes it transparent so that the
cartridge ROM is accessible.
{{{
SDX OSS BAS OPERATING CONDITION
$01 $08 1 in DOS or low RAM
$0C $08 1 in high RAM (X.COM)
$0C $08 0 in BASIC
$08 on 1 in cartridge
}}}
If you're going to play with SDX banks remember that any read or
write to a $D5Ex address will affect an OSS cartridge and TRIG3.
Since TRIG3 is affected, GINTLK and CARTCK also come into play. So
the example given of how to access RAM under a cartridge needs to
be modified if SDX is present. Let's look at a subroutine to access
RAM in the cartridge space taking in the possibility of the
presence of BASIC, SDX, or an OSS cartridge.
{{{
ROMCTL
LDA PORTB
PHA
ORA #$02 Any Basic rom off
STA PORTB
LDA RAMTOP This might be easy
CMP #$A0+1
BCC NOLUCK Not quite.
PLA See note a. following
STA BASICF for an explanation
JMP DOSTUFF
NOLUCK
LDA TRIG3 Is a cart present?
BNE CART Yes, go.
JSR DOSTUFF Still fairly easy
PLA
STA PORTB
RTS
CART
PLA See note a. following
STA BASICF for an explanation.
SEI Kill stage 2 vblank
LDA $AFFF Get OSS bank number
PHA Save it
STA $D5E8 Turn off both carts
JSR DOSTUFF
}}}
We know a cartridge was on. Now
we have to restore it correctly.
{{{
PLA Recover bank number
CMP #$10 Valid for OSS? (note c.)
BCS SDX No, must be SDX
TAY
STA $D500,Y Restore OSS cart bank
BCC CARXIT Go always
SDX
STA $D5E1 Enable SDX normal bank
STA $D508 Kill OSS cart (note b.)
CARXIT
CLI
RTS
}}}
a. The reason for discarding the PORTB entry value is to allow for
512k+ RAM expansions. As mentionned previously, the OS doesn't know
extra RAM exists and has no way of knowing BASIC may not exist on
large upgrades. As a result, it sets PORTB and BASICF based solely
on the Option key at boot and uses BASICF to determine which status
to restore on a reset. On large RAM upgrades this leads to major
problems for programs using extra RAM as the program can end up in
the wrong 256k bank. Unless BASIC is actually on, it is always
advisable to flag it off and to set its bit high in PORTB.
b. We knew a cartridge was on or we never would have got to that
portion of the code. As it wasn't the OSS cartridge, it had to be
SDX. But, because the dumb OSS cartridge reacts to the $D5E1
address, we had to turn it off again after enabling SDX. For the
same reason, a single access of $D5E8 was sufficient to turn both
off.
c. The comparison of the bank number to 16 to determine its
validity as an OSS bank number is that used by ICD in the code for
the RT8 handler. The test is, I believe, made on the assumption
that the X cartridge is in bank 1 where the value at $AFFF is 87
for version 4.20. There are two SDX banks where values less than 16
are found at $AFFF, namely 0 (value 7) and 4 (value 3).
!! The R-Time 8
Control of the RT8 is built into all versions of Sparta from 3.2
on. As far as I know, all you can do with the RT8 is set or get
time and date information. The only problem in doing this is that
accessing the RT8 registers will affect an OSS cartridge. Because
of this the RT8 has two identical user accessible registers $D5B8
and $D5B9. According to the RT8 source, addressing $D5B8 will turn
off a cartridge and $D5B9 will turn one on.
The RT8 has seven internal registers which work in binary coded
decimal. Starting from #0 they are: seconds, minutes, hour, day of
month, month, year, and day of the week (#6). Seconds and minutes
range from 0-59, hours from 0-23, day from 1-31, month from 1-12,
year from 0-99. Day of the week ranges from 0 (Saturday) to 6
(Friday). When you read or write one of these registers the
sequence is always the same:
1 Wait until the RT8 is not busy.
2 Store a value from 0 to 6 into $D5B8 or $D5B9 indicating the register you wish to address.
3 Read/write the same address to get/set the most significant digit (the low four bits are the valid data).
4 Read/write the same address to get/set the least signifigant digit (the low four bits are the valid data).
The source code released by ICD indicates that reading a register
should be repeated up to three times accepting two values that
match or, failing a match, the first one. When setting a register,
it recommends reading it immediately afterward to ensure the value
was really accepted and allowing 10 tries.
Here's one way to read and write RT8 registers without worrying
about an OSS cartridge. Much of this is from the source released by
ICD. In this example, the buffer is set up in the same order as the
RT8 registers. With Sparta, you would have to cross refer to the
order in which DOS saves time and date and keep a separate byte for
day of the week.
{{{
*= $F0 Floating point zero page
TEMP1
*= *+1
TEMP2
*= *+1
RETRY
*= *+1
BUFFER
*= *+1 Seconds
*= *+1 Minutes
*= *+1 Hours
*= *+1 Day of month
*= *+1 Month
*= *+1 Year
*= *+1 Day of week
*= WHEREVER
SEI Kill vblank2
LDA $AFFF Get any cart bank
CMP #$10 Is it valid?
BCC SAVBNK Yes go, else use
LDA #$08 the "off" value.
SAVBNK
PHA Save cart bank
}}}
Verify rt8 present and working
{{{
JSR READ Get seconds
CMP #60
BCS GLITCH if >59 then error
STA TEMP1
LDA RTCLOK+2
ADC #90
WAIT
CMP RTCLOK+2 Wait about 1.5"
BNE WAIT
JSR READ Read again
CMP TEMP1 Same as last?
BEQ GLITCH Yes, not working
SEC
SBC TEMP1 Ensure <3
BCS CHECK3 It is
ADC #60 else did it roll over?
CHECK3
CMP #3
BCC RT8OK Yes, rt8 is ok
GLITCH
LDA # <RT8ERR Set for error message
LDX # >RT8ERR
EXIT
STA ICBAL
STX ICBAH
LDA #9 Print to eol
STA ICCOM
STA ICBLH Plenty of length
PLA
TAX Restore cart bank
STA $D500,X
CLI restore vblank2
LDX #0 Select channel 0
JMP CIOV Exit with message
}}}
First read the clock regs into the buffer
{{{
RT8OK
LDX #6 Point to day of week
RCLOOP
JSR READ
DEX
BPL RCLOOP
}}}
Change values you want in the buffer and
then write it back to the clock
{{{
LDX #6
RCLOOP
JSR WRITE
BNE GLITCH Exit if write failed
DEX
BPL RCLOOP else do all 7
LDA # <RT8SET Set success message
LDX # >RT8SET
BNE EXIT Branch always
RT8ERR
.BYTE "RT8 Error",155
RT8ERR
.BYTE "RT8 Set",155
; Subroutine: wait til clock is
; not busy or exit on time out.
; Enter: x=clock reg to access (0-6)
; Exit: x unchanged, clock ready,
; and clock register selected
WAITCL
LDY #$FF Timeout value
WAITC
LDA $D5B8
AND #$0F If low nybble=0
BEQ READY clock not busy
DEY
BNE WAITC Else time out
READY
STX $D5B8 Set reg #x to read/wrt
RTS
; Subroutine: read rt8 reg once
; In x=reg#
; Out a=byte x=reg#
READ1
JSR WAITCL
LDA $D5B8 Get high byte
LDY $D5B8 Get low byte
AND #$0F Convert bcd to hex
STA TEMP1
ASL A Clears carry
ASL A
ADC TEMP1
ASL A
STA TEMP1 Temp1=(high*10)
TYA Add in low byte
AND #$0F
ADC TEMP1 Return byte in a
RTS Note c=0 x=x y=trig3
; Subroutine: read a clock register
; and accept best 2 of 3 readings
; or the first if none match.
; in: x=reg#
; out: a=value(}
READ
JSR READ1
STA TEMP1
JSR READ1
CMP TEMP1
BEQ REXIT
STA TEMP2
JSR READ1
CMP TEMP2
BEQ REXIT
LDA TEMP1
REXIT
RTS
; Subroutine: write clock register
; with value stored in buffer offset
; by x. Allow 10 tries.
; in: x=reg#
; out: x=reg#, z flag set if ok
WRITE
LDA #9
STA RETRY
WRT2
LDA BUFFER,X
LDY #$FF Convert to bcd
SEC
SUB10
INY
SBC #10
BCS SUB10
ADC #10
PHA low byte
TYA
PHA high byte
JSR WAITCL y=trig3
PLA High byte
STA $D5B8
PLA
STA $D5B8 Low byte
JSR READ Verify it set
CMP BUFFER,X correctly
BEQ WRTXIT It did!
DEC RETRY
BPL WRT2 Never 0 if failed
WRTXIT
RTS
}}}
!! The Multiplexer! Operating System (MUX)
The MUX OS makes frequent access of registers in the $D57x range.
A cursory glance at the ROM reveals it uses the following registers
on a read-only basis 1, 6 and 7. Registers 2, 3, B, C and E are
accessed as write-only while 0 is read/write. Every one of these
addresses will affect an OSS cartridge. I found no indication in
the MUX code that it makes any effort to accommodate a cartridge,
GINTLK or TRIG3.
While I have managed to work around an SDX cartridge and an RT8 in
controlling BASIC, OSS cartridges, and even Atari cartridges (with
SDX present), I can see no way of doing so with the MUX OS. I
believe the idea with the MUX is that once the plug's in the port,
you can't use a cartridge anyway. That's kind of unfortunate as it
denies you use of a cartridge and access to the built-in monitor.
As I don't have a MUX to experiment with, I leave that to someone
else.
!! Cold and Warm Starting and Parallel Devices (PD's)
If you turn off an OSS cartridge and then re-boot under most
versions of SpartaDOS, you get a "soft" lockup as DOS will enable
a cartridge as part of its boot process in testing for BASIC XE.
Simply hit Reset and the computer will boot again with the
cartridge on. If you want to reenable the SDX cartridge after
having turned it off using the COLD command, the method should be
obvious by now. What is not obvious are a few other addresses and
quirks in warm and cold starting.
On boot the OS calculates ROM checksums and compares them to ones
stored in the OS itself. If these don't match, boot doesn't happen;
you end up staring at the Self Test screen and a red bar under the
heading "ROM". This can easily occur on a system with a PD because
cold starting the computer does not cold start the PD any more than
it does a cartridge. If PD ROM is enabled, as for a modem handler
on a BBS, and you attempt to cold start, you will inevitably end up
in Self Test because the ROM checksum will fail. It is supposed to
include the floating point ROM at $D800, but instead gets a bank of
the PD ROM.
Finally, if you're just going to warm start, decide whether or not
you want to emulate a press of the Reset key. Jumping to the warm
start vector at $E474 is not the same as pressing the key; the
vector points past the hardware initialization routines. If you
want to ensure you clear out all garbage (left over player
missiles, keypress, etc.) you have to use the chip reset vector.
The following routine has varying results dependant on the entry
point. To enable SDX, enter at XCART. To enable an OSS cart alone,
enter at CART. To just cold start without touching the cartridges,
enter at COLD. To simulate a press of Reset, enter at WARM.
{{{
XCART
SEI Always before $D5xx access
STA $D5E0 Enable SDX
CART
SEI Again, dependant on entry
STA $D500 Enable OSS cart
COLD
DEC COLDST Force a boot
WARM
SEI Just in case
LDX #0
STX NMIEN Ditto
STX $D1FF Enable floating point
STX $D1E2 Kill MIO RAM (this and
DEX following just in case)
STX $D1BC turn off BlackBox RAM
STX PORTB Ensure ROM OS is on to go
JMP ($FFFC) through chip reset vector
}}}
I won't go any further on this as the Black Box and MIO are, unlike
Atari and OSS products, fairly well documented. Whew, when I
started this I never thought it would turn into such a monster nor
did I think it would take so long to come up with all the ins and
outs. Now that you know how easy it is to make use of the RAM under
cartridges, under the OS and in extra memory, I look forward to
seeing some practical utilities. Here's few suggestions:
* "Pop-up" help screens for use in MAC/65, Action! or BASIC.
* An 8k RAM cache.
* A "pop-up" calculator.
* A resident DUP.SYS.
* etc.
!! LATE NOTES
I recently was browsing through some old computer magazines and
came across an article by Bill Wilkinson dealing with 130XE RAM
control. In it he stated that 16k Atari cartridges such as Atari
Writer Plus occupy the address space from $8000 to $BFFF rather
than using bank switching.
As a final addition to this text, I've tacked on part 4 which is
MAC/65 source code to produce two simple COM files to dump
cartridges to disk for examination. The programs are not
sophisticated but will do the trick.
Revision: 16 Feb 96
!! LATER NOTE
A message by Bill Wilkinson posted on comp.sys.atari.8bit on 12
August 95 validates much of what has been said and revealed a bit
more of cartridge construction. His memory was a bit off on address
ranges, but his stuff about 4k banking is right on. I dumped MAC/65
and Action! to disk files and verified that, in each cartridge, the
code from $B000-$BFFF is identical in all three banks. In effect,
this indicates a mapping as follows (using MAC/65 as an example):
{{{
Addr: $D500 $D501 $D509 $D508
$A000
c0 c1 c9 RAM
$AFFF
$B000
cc cc cc RAM
$BFFF
}}}
Where: "Addr" is the access address used to enable the configuration,
"c0" etc. is the switchable 4k bank and "cc" is the common 4k bank.
Substituting "3" and "4" for "1" and "9" above would produce a map
of the Action! cartridge.
{{{
.OPT NO LIST,NO EJECT
; SAVE #D1:CARTDUMP.M65
;
;
; ASM ,,#D1:CARTDUMP.COM
;
; Copy OSS cartridge banks to
; D1:CARTIMAGE.CBx where x is bank
;
ICCOM = $0342
ICBAL = $0344
ICBLL = $0348
ICAX1 = $034A
CIOV = $E456
PORTB = $D301
DMACTL = $D400
SDMCTL = $022F
GINTLK = $03FA
TRIG3 = $D013
;
*= $2F00
;
; The first 64 bytes are dumped to
; the CARIMAGE.MAP file
;
RAMROM
*= *+16 0=rom $FF=ram
BANKNO
*= *+16 byte at $AFFF
BARRAY
*= *+16 0=valid rom bank
TRIG3A
*= *+16 trig3 reading for bank
CURBNK
*= *+1 Base test bank
TESTBK
*= *+1 Bank being tested vs base
CBSAVE
*= *+1 Entry cart status
PBSAVE
*= *+1 Entry portb status
;
*= $3000
START
LDA #$60
STA START
LDX #0
TXA
ZLOOP
STA $2F00,X Clear data page
INX
BNE ZLOOP
;
LDA PORTB
STA PBSAVE
DEX
STX PORTB
LDY #$08
LDA GINTLK
BEQ HAVBNK
LDY $AFFF
HAVBNK
STY CBSAVE
;
SEI Kill vblank 2 before
LDX #15 playing with cart
LOOP0
STA $D500,X First test
LDA TRIG3 if rom or ram
STA TRIG3A,X
LDA $AFFF Get any bank number
STA BANKNO,X
INC $AFFF Check ram
CMP $AFFF
BEQ ISROM No, it's rom
STA $AFFF
DEC RAMROM,X Set rom/ram map to ram
DEC BARRAY,X Show no rom to test
ISROM
DEX
BPL LOOP0
;
STA $D500,Y Cartridge normal
CLI vblank now ok
;
STX CURBNK Start base at -1
LDY #$FF
LOOP1
INY
CPY #16 All higher ones tested?
BCS NEXTBASE Yes, bump test base
LDA BARRAY,Y Unique rom this bank?
BMI LOOP1 No, ram or a dup
TYA
TAX
LOOP2
INX Test all higher
CPX #16 banks for duplicate
BCS LOOP1 All higher tested.
LDA BANKNO,X Was there a valid
CMP #16 bank number?
BCS FAIL No
EOR BANKNO,Y Same as current?
BNE LOOP2 No
FAIL
DEC BARRAY,X Yes, flag a duplicate
BMI LOOP2 Go always
NEXTBASE
INC CURBNK If at bank 15 there's
LDX CURBNK none higher to compare
CPX #15 with
BCS MAPWRT So go finish up
;
LDA BARRAY,X Check if bank valid
BMI NEXTBASE No, ram or duplicate
STA $D500,X Enable it
LDY #0 Copy it to $6000
LDA #$A0
STA CLOOP+2
LDA #$60
STA CLOOP+5
CLOOP
LDA $A000,Y
STA $6000,Y
INY
BNE CLOOP
INC CLOOP+2
INC CLOOP+5
BPL CLOOP
JSR WRITE Write it to disk
JMP NEXTBASE
MAPWRT
LDX CBSAVE
STA $D500,X
LDA PBSAVE
STA PORTB
LDX #$10
LDA # <MSPEC
STA ICBAL,X
LDA # >MSPEC
STA ICBAL+1,X
LDA #3
JSR GOCIO
BMI CLOSE
LDA # <RAMROM
STA ICBAL,X
LDA # >RAMROM
STA ICBAL+1,X
LDA #48
STA ICBLL,X
LDA #0
BEQ BPUT
WRITE
TXA
CLC
ADC #'0
CMP #'9+1
BCC ISHEX
ADC #6
ISHEX
STA BANKID
LDX #$10
JSR CLOSE
LDA # <FSPEC
STA ICBAL,X
LDA # >FSPEC
STA ICBAL+1,X
LDA #8
STA ICAX1,X
LDA #0
STA ICAX1+1,X
LDA #3
JSR GOCIO
BMI CLOSE
LDA # <$6000
STA ICBAL,X address
STA ICBLL,X length
LDA # >$6000
STA ICBAL+1,X address
LDA # >$2000
BPUT
STA ICBLL+1,X length
LDA #11 bput
JSR GOCIO
CLOSE
LDA #12
GOCIO
STA ICCOM,X
JMP CIOV
;
; Copy cartridge bank to $4000
;
BCOPY
SEI
STA $D500,X
LDA # >$A000
STA LOOP4+2
LDA # >$4000
STA LOOP4+5
LDX #32
LDY #0
LOOP4
LDA $A000,Y
STA $4000,Y
INY
BNE LOOP4
INC LOOP4+2
INC LOOP4+5
DEX
BNE LOOP4
LDX CBSAVE
STA $D500,X
RTS
;
FSPEC
.BYTE "D1:CARIMAGE.CB"
BANKID
.BYTE "0",155
MSPEC
.BYTE "D1:CARIMAGE.MAP",155
.OPT NO LIST
.END
.OPT NO LIST,NO EJECT
; SAVE #D1:SDXDUMP.M65
;
;
; ASM ,,#D1:SDXDUMP.COM
;
; Copy SDX cartridge banks to
; D1:SDXIMAGE.CBx where x is bank
;
ICCOM = $0342
ICBAL = $0344
ICBLL = $0348
ICAX1 = $034A
CIOV = $E456
PORTB = $D301
DMACTL = $D400
SDMCTL = $022F
GINTLK = $03FA
TRIG3 = $D013
;
; First 64 bytes to SDX.MAP file
;
*= $2F00
RAMROM
*= *+16 0=rom $FF=ram
BNUMBR
*= *+16 Value at $AFFF
BARRAY
*= *+16 0=valid, unique rom bank
TRIG3A
*= *+16 trig3 reading for bank
;
CURBNK
*= *+1 Base test bank
CBSAVE
*= *+1 Entry cart status
PBSAVE
*= *+1 Entry portb status
*= $3000
START
LDA #$60
STA START
LDX #0
TXA
ZLOOP
STA $2F00,X Clear data page
INX
BNE ZLOOP
LDA PORTB
STA PBSAVE
DEX
STX PORTB Basic rom off
;
; SDX OSS BAS OPERATING CONDITION
; $0C $08 1 in high ram (x.com)
; $0C $08 0 in basic
; $08 on 1 in oss cartridge
; $01 $08 1 in dos or low ram
;
LDA #$08 a=$08=oss off
LDX #$0C x=$0C=sdx off
LDY TRIG3 Is this valid?
BEQ SAVEOX Yes both are off
TAX x=$08=sdx xprnt
LDA $AFFF a=ossbnk
CMP #$10 Valid?
BCC SAVEOX x=$08=sdx xprnt a=oss on
TXA a=$08=oss off
LDX #$01 x=$01=sdx on
SAVEOX
STA CBSAVE
STX XCSAVE
SEI Kill vblank2 before
LDX #$0F playing with carts
LOOP0
STA $D5E0,X Select SDX bank
STA $D508 Kill any OSS bank
LDA TRIG3 Save trigger value
STA TRIG3A,X
LDA $AFFF Also bank id value
STA BNUMBR,X
INC $AFFF Check ram
CMP $AFFF
BEQ ISROM No, it's rom
STA $AFFF
DEC RAMROM,X Set rom/ram map to ram
DEC BARRAY,X Show no rom to test
ISROM
DEX
BPL LOOP0
STX CURBNK
;
TEST1
INC CURBNK Start sdx bank=0
LDX CURBNK
CPX #$10
BCS TESTED
LDA BARRAY,X Unique ROM to test?
BMI TEST1 No, ram or duplicate
JSR BCOPY Copy to ram
JSR WRITE Write to disk
LDX CURBNK
NXTTST
INX Next higher bank
CPX #$10
BCS TEST1 All done, bump base
LDA BARRAY,X Ram or a duplicate?
BMI NXTTST Yes, skip it
JSR BTEST Go test it and set
JMP NXTTST array if applicable.
;
TESTED
LDX XCSAVE
STA $D5E0,X
LDX CBSAVE
STA $D500,X
LDA PBSAVE
STA PORTB
LDX #$10
LDA # <MSPEC
STA ICBAL,X
LDA # >MSPEC
STA ICBAL+1,X
LDA #3
JSR GOCIO
BMI CLOSE
LDA # <RAMROM
STA ICBAL,X
LDA # >RAMROM
STA ICBAL+1,X
LDA #64
STA ICBLL,X
LDA #0
JSR BPUT
CLI
RTS
;
WRITE
TXA
CLC
ADC #'0
CMP #'9+1
BCC ISHEX
ADC #6
ISHEX
STA BANKID
LDX #$10
JSR CLOSE
LDA # <FSPEC
STA ICBAL,X
LDA # >FSPEC
STA ICBAL+1,X
LDA #8
STA ICAX1,X
LDA #0
STA ICAX1+1,X
LDA #3
JSR GOCIO
BMI CLOSE
LDA # <$6000
STA ICBAL,X address
STA ICBLL,X length
LDA # >$6000
STA ICBAL+1,X address
LDA # >$2000
BPUT
STA ICBLL+1,X length
LDA #11 bput
JSR GOCIO
CLOSE
LDA #12
GOCIO
STA ICCOM,X
CLI
JSR CIOV
SEI
RTS
;
BCOPY
STA $D5E0,X
STA $D508
LDA #$A0
STA BCLOOP+2
LDA #$60
STA BCLOOP+5
LDY #0
BCLOOP
LDA $A000,Y
STA $6000,Y
INY
BNE BCLOOP
INC BCLOOP+2
INC BCLOOP+5
BPL BCLOOP
RESTOR
LDY XCSAVE
STA $D5E0,Y
LDY CBSAVE
STA $D500,Y
RTS
;
BTEST
STA $D5E0,X Enable bank
STA $D508
LDA #$A0
STA TLOOP+2
LDA #$60
STA TLOOP+5
LDY #0
TLOOP
LDA $A000,Y
EOR $6000,Y
BNE DIFFER Skip array change
INY
BNE TLOOP
INC TLOOP+2
INC TLOOP+5
BPL TLOOP
DEC BARRAY,X Flag duplicate
DIFFER
RTS
;
FSPEC
.BYTE "D1:SDXBANK."
BANKID
.BYTE "0",155
MSPEC
.BYTE "D1:SDX.MAP",155
.OPT NO LIST
.END
}}}
- J.K. Picken (EOF) -
!!! Part 2 - THE OSS SUPERCARTRIDGEs
Copyright (c) 1984 Ken Roser (nope, OSS!)
__NOTE:This article originally appeared in the Jersey Atari Computer Group Newsletter.__
OSS has recently introduced BASIC XL and ACTION in a cartridge referred to as the supercartridge. This article will explain the advantages of using such a cartridge and describe in detail how the cartridge works. The advantage of using the supercartridge hardware is that one can have 16K (K = 1 kilobyte) of ROM and 8K of RAM all within only 8K of memory address space. What this means is more of your precious memory is available for your programs and data instead of being used up by a 16K cartridge or a large applications program or interpreter. This efficient use of memory resources is accomplished by selectively activating 4K segments of two 2764 (8 Kilobyte x 8 bit) EPROMS. Only two 4K banks out of the possible 4 can be selected at one time. There are 2 EPROMS located on the supercartridge board that I have designated ROM A and ROM B. The upper 4K of ROM A will always reside in the $B000-$BFFF address range when the RAM is deselected. The other 4K banks (ROM B upper, ROM B lower, and ROM A lower) can selectively be mapped into the $A000-$AFFF address range. Optionally all the ROMs can be deselected and the computer's existing RAM can be accessed in the $A000-$BFFF memory range. The bank switching is accomplished by writing to a memory address within the range $D500-$D5FF. When this write occurs, address bits A0 thru A3 are latched into a 4 bit register located on the cartridge. The status of each bit determines the current mapping configuration to be put into effect. The following tables are used to show what each address bit actually does in the cartridge. A0 always controls the selection of ROM A. A1 always controls the selection of ROM B. A2 selects which half of ROM B is used when it is selected. A3 selects/deselects RAM. BIT A0 This table shows what portion of ROM A will be used in each address range dependent on the state of A0.
{{{
A000-AFFF B000-BFFF
_____________________________________
| | |
A0=0 | nothing | ROM A upper |
|__________________|__________________|
| | |
A0=1 | ROM A lower | ROM A upper |
|__________________|__________________|
}}}
BIT A1
This table shows when ROM B is selected. The
half of ROM B used is determined by A2.
{{{
A000-AFFF B000-BFFF
_____________________________________
: : :
A1=0 : ROM B select : nothing :
:__________________:__________________:
: : :
A1=1 : nothing : nothing :
:__________________:__________________:
}}}
BIT A2
This table shows which half of ROM B is used
when it is selected.
{{{
____________________________
: :
A2=0 : Lower 1/2 of ROM B (A12=0) :
:____________________________:
: :
A2=1 : Upper 1/2 of ROM B (A12=1) :
:____________________________:
}}}
BIT A3
This table shows the effect of A3.
{{{
____________________________
: :
A3=0 : ROM Selected/Ram deselected:
:____________________________:
:
A3=1 : RAM selected/ROM deselected:
:____________________________:
}}}
Make note that some of these options can not be selected simultaneously. For example, an illegal option would be A0=1 and A1=0. In that case both ROM A lower and ROM B would be selected for the $A000-$AFFF address range. Possible Valid Configurations: These diagrams represent the segments of ROM and/or RAM that will be activated when the address shown is written to.
{{{
__________ __________
$A000: : $A000: :
: ROM B : : nothing :
: lower : : selected :
$AFFF:__________: $AFFF:__________:
$B000: : $B000: :
: ROM A : : ROM A :
: upper : : upper :
$BFFF:__________: $BFFF:__________:
A0=0 A0=0
A1=0 A1=1
A2=0 A2=0,1
A3=0 A3=0
$D500 $D502 or $D506
__________ ___________
$A000: : $A000: :
: ROM A : : ROM B :
: lower : : upper :
$AFFF:__________: $AFFF:__________:
$B000: : $B000: :
: ROM A : : ROM A :
: upper : : upper :
$BFFF:__________: $BFFF:__________:
A0=1 A0=0
A1=1 A1=0
A2=0,1 A2=1
A3=0 A3=0
$D503 or $D507 $D504
__________
$A000: :
: RAM :
: :
$AFFF:__________:
$B000: :
: RAM :
: :
$BFFF:__________:
A0=0,1
A1=0,1
A2=0,1
A3=1
$D508-$D50F
}}}
If one was to combine the above configurations into one diagram, you would get something like this representing the possible configurations:
{{{
_______________________________________
$A000: : : :
: ROM A : ROM B : ROM B :
: lower : lower : upper :
$AFFF:_____________:_____________:___________:
$B000: :
: ROM :
: upper :
$BFFF:_______________________________________:
}}}
When ROM is swapped out for RAM, the entire range $A000-$BFFF no longer has ROM. The ROM can only be swapped out in the entire 8K range. In the ACTION! cartridge ROM A is designated MA and ROM B is designated LI. In the BASIC XL cartridge ROM A is designated as BAS-H and ROM B is designated as BAS-L.
{{{
CIRCUIT BOARD LAYOUT
_________________________________
: ___________ :
: : ###_ : : :
: # __________ D 74LS02 : :
: # : : :___________: :
: # D 74LS175 : ___________ :
: : :__________: : : :
: D 74LS00 : :
: -#- -#- :___________: :
: :
: ____________ ____________ :
: :1 28: :1 28: :
: :2 27: :2 27: :
: :3 26: :3 26: :
: :4 25: :4 25: :
: :5 24: :5 24: :
: :6 23: :6 23: :
: :7 ROM B 22: :7 ROM A 22: :
: :8 21: :8 21: :
: :9 20: :9 20: :
: :10 19: :10 19: :
: :11 18: :11 18: :
: :12 17: :12 17: :
: :13 16: :13 16: :
: :14 15: :14 15: :
: :____________: :____________: :
: :
:_ _:
: :
:0 0 0 0 0 0 0 0 0 1 1 1 1 1 1:
:1 2 3 4 5 6 7 8 9 0 1 2 3 4 5:
:_____________________________:
COMPONENT SIDE PINOUT
: :
:_ _:
: :
: :
:A B C D E F H J K L M N P R S:
:_____________________________:
FOIL SIDE PINOUT
}}}
!!! Part 3: Cartridge slot descriptions
by Jindrich Kubec
!! Left slot pinout (all models) ARD4if cartridge maps to $8000-$9FFF area
{{{
(act H)1/S4 selects lower bank (act L)
BGND 2A3
CA4 3A2
DA5 4A1
EA6 5A0
FA7 6D4
HA8 7D5
JA9 8D2
KA12 9D1
LD3 10D0
MD7 11D6
NA11 12/S5 selects upper bank (act L)
PA10 13+5V
RR/WR/W - read (act H), write (act L)14RD5 if cartridge maps to
$A000-$BFFF area (act H)
SB-PHI2buffered phase 2 clock15/CCTL active when written to $D5xx
(act L)
}}}
!! Right slot pinout (only 800) AB-PHI2 1R/W
{{{
BGND 2A3
CA4 3A2
DA5 4A1
EA6 5A0
FA7 6D4
HA8 7D5
JA9 8D2
KA12 9D1
LD3 10D0
MD7 11D6
NA11 12/S4 selects lower bank (act L)
PA10 13+5V
RR/WR/W - read (act H), write (act L)14RD4 if cartridge maps to
$8000-$9FFF area (act H)
SB-PHI2buffered phase 2 clock15/CCTL active when written to $D5xx
(act L)
}}}
Parts are (always?) at back (XL)/bottom (XE) part of the cartridge. Connector orientation is S-A from front, 1-15 from back.
!! Cartridge basics
There are three different 'windows' or banks in the memory:
1 Bank $A000-$BFFF is selected by low state on S5. Its presence is signaled by high state on RD5. This signal is attached to TRIG3 in XL/XE series. Used in left carts only.
2 Bank $8000-$9FFF is selected by low state on S4. Its presence is signaled by high state on RD4. Used in both left and right slot carts.
3 'Bank' $D500-$D5FF is selected by low state on CCTL. It's used for bankswitching. (mapping ports etc.)
Czech speciality are cartridges with buttons. There are 2 different ways:
1 the button only connects RD5 to computer. So you push it, press reset, make the selection (if any) and then release the button. The program will be loaded from cartridge and will not take that much amount of memory (minimum is 8KB, obviously).
2 the button turns on RD5 and leaves it on. After reset, user could do some selections and cartridge will turn off when needed.
Romox released 'blank' 16KB cartridges which could be programmed in special
machines. They were called Edge Connector Programmable Cartridges.
Emulated: Atari800
!! OSS carts
Banks: Usually contain 4 4KB banks. One of the banks is mapped in
$B000-$BFFF.
Other banks are mapped to $A000-$AFFF.
Double eprom PCB (OSS DBL): Older scheme, uses 74LS175 (4bit register???),
2 eeproms and uses 4 bits of address bus.
Physical order of banks: ROM A = 3, M; ROM B = 0, 4
PCB Top (42 KB JPG), PCB Bottom (42 KB JPG) (with parts)
{{{
A0 if 1, selects AL
A1 if 0, selects B
A2 if 0, selects BL, if 1 selects BH (A1 must be 0!)
A3 if 0, cart on, if 1, cart off.
AddrA000-AFFFB000-BFFFRD5
0000BLAU1
0001AL+BL = shitAU1
0010nothing = FF'sAU1
0011ALAU1
0100BHAU1
0101AL+BH = shitAU1
0110nothing = FF'sAU1
0111ALAU1
1xxxoffoff0
}}}
Single rom PCB (OSS SNG):
Newer scheme, uses 2 d-flipflops, bits A0 and A3.
Physical order of banks: M, 0, 9, 1.
{{{
A3A0A000-AFFFB000-BFFFRD5 Values
00bank 0bank m10,2,4,6
01bank 1bank m11,3,5,7
10offoff08,A,C,E
11bank 9bank m19,B,D,F
}}}
Examples:
Action!, MAC/65 V1.00, MAC/65 1.01, MAC/65 1.02, Basic XE,
Basic XL 1.02, Basic XL 1.03, Writer's Tool;
Emulated: Atari800
!! SDX carts
Banks: Contain 8 8KB banks. Access to base+0-7 turns on banks 0-7 in
$A000-$BFFF
area. Access to base+8-F turns the cart off.
SDX: Base is $D5E0.
Diamond: Base is $D5D0.
Express: Base is $D570.
Better said: Cartridge looks for low CCTL and match in A4-A7. For SDX it
is 0xE (1110), Diamond 0xD (1101), Express 0x7 (0111). If A3 is high, cart is turned off. If A3 is low, the bank whose number is in A0-A2 is selected. I'm not sure what happens when turning cart off, but I think that it turns off RD5 only.
Examples:
Sdx 4.18, Sdx 4.19, Sdx 4.20, Sdx 4.21, Sdx 4.22, Express, Diamond GOS 1,
Diamond GOS 2, Diamond GOS 3, MIO Diagnostics
Emulated: Atari800
!! R-Time 8
Pass thru cartridge with battery-backup for real-time clock.
Emulated: Atari800 - read only is enough.
!! XEGS carts
Banks: Contain n 8KB banks. Bank n-1 is mapped at $A000-$BFFF. Banks 0
to n-1 are mapped to $8000-$9FFF by writing the number of bank to any of $D500 registers.
Examples (32KB):
Archon, Blue Max, Crystal Castles, Into the Eagle's Nest, Food Fight,
Star Raiders II;
Examples (64KB):
Ballblazer, Battlezone, Choplifter!, David's Midnight Magic, Deflektor, Dark Chambers,
Desert Falcon, Hardball, Mario Bros., Rescue on Fractalus, Tower Toppler, Thunderfox
Examples (128KB):
(Bug Hunt and Lode Runner probably contain 64KB rom, but start from
the bank 8.)
Ace of Aces, Airball, Barnyard Blaster, Bug Hunt, Crime Buster, Crossbow, Fight Night, Flight Simulator II, Gato, Karateka, Lode Runner, Summer Games;
Emulated: Atari800
!! XEGS demo cartridge
Banks: 128 KBs.
Contains:
* XEGS 64 - Flight Simulator 2 (shortened demo version)
* XEGS 32 - One on One (same version as on XEGS cart)
* LS16 - Joust (same version as on cart)
* LS16 - Ms. Pacman (same version as on cart)
Does change game on each reboot (binary counter powered by capacitors).
Emulated: Unemulated (not needed).
!! Telelink 2 cartridge
Banks: Just one 8kb bank at A000-BFFF. Additional hardware is one X2212
nonvolatile SRAM, containing 256 x 4 bits, for storing telephone numbers. It's accessed by reading/writing 9000-90FF. There is also read access to $D501 and write access to $D502, don't know yet for what, but probably for setting read/write mode of the SRAM. The cartridge uses RD4 hardwired to +5V, what means that it takes full 16KB of address space. Not very elegant solution.
Emulated: Unemulated
--++ MD-DOS cartridge
Banks: Same as OSS SNG cartridges. Uses two additional bits (A5,A4) for
selecting 'subcart'. It thus has 4x16KB = 64KB. Also has button, don't know
for what it is used (probably for calling the cartridge).
MD Dos
Emulated: My experimental Atari800 emulator - but with possible bugs.
!! JRC cartridges
Toolbox III: Contains 64KB bankswitched cart with reset button.
Rambox2: EEPROM part same or very similar to Toolbox III. Additionally contains 256KB of RAM. This ram could be accessed by TT-Dos and BeWe Dos.
Toolbox III
Rambox2
EEPROM part: 8x8KB banks. Selected by D6, D5 & D4. Bank number is remembered
when A7 is off (D500-D57F). If D7 is on, cartridge is off. If button
is pressed, register is cleared, RD5 is on, main bank selected.
RAM part:
{{{
ram bank select:
X = 00 - 7F (7bits)
A = A | $F0 (4bits)
STA $D500,X
}}}
Together it's 11 bits of bank address. You can address $80 bytes of memory
in region $D580 (7bits). 11 bits + 7 bits = 18 bits = 256KB of RAM.
memory write:
{{{
LDA (BUFRLO), Y
STA $D580, Y
}}}
memory read:
{{{
LDA $D580, Y
STA (BUFRLO), Y
}}}
Y = 00 - 7F. Uses previously set bank address.
Emulated: My experimental Atari800 emulator.
!! ATRAX cartridge
Banks: Contains 16 x 8KB banks (128KB). Uses A000-BFFF region. Bits 0-3 select
bank. Bit 7 turns cart off. Menu program loads standard Atari dos executable,
then turns cart off. I was told that 16 different carts exists.
ATRAX no.5
Emulated: Atari800
!! Bounty Bob cartridge
Banks: Very strange bankswitching method. Contains main bank at A000-BFFF. From 8000-8FFF is first bank, 9000-9FFF is second bank. They are switched by accessing 8FF6-8FF9 (9FF6-9FF9). In each bank there's 4 x 4 KBs. Totally, it's 2 x 4 x 4 + 8 = 40 KBs. I was told that the cartridge is almost same as 5200 version and such cart contains only three chips: one 8KB rom, and two special self-switching 16KB roms. What circuitry is inside those chips is unknown to me.
Bounty Bob
Emulated: Atari800, BBEmu (Bounty-Bob Emu!)
!! 128/256 K RamCart
Banks: Unknown.
Emulated: Unemulated.
!! A/D Converter
Banks: None. Uses lower four bits of $D500 for getting the digitized
sound from mono analog input.
Emulated: Unemulated.
!! MPP Super Charger
Banks: ???. May contain 'hardware accelerator chips'. Used together with game disk 'Assault Force'. (Still available from BEST Electronics!)
Emulated: Unemulated.
!! PILL carts
The PILL!
Super PILL!
Super Cart (by Frontrunner)
Banks: None. Just a way to barl the computer into thinking that a cart.
was inserted (due to the copy protection of some carts).
Emulated: ?
!! Willams multibanked cartridge
Banks: Contains 8 x 8kb banks. Writing to $D500 turns on first bank (on bootup), writing to $D507 turns on last bank. Writing to $D508 turns cart off. Video61 uses this design for their newly released 'big' cartridges.
Emulated: Atari800 (from >1.2.2)
!! Thompson Proburner
EEPROM burner.
Banks: Contains 8kb in right slot, accesses D500, probably hardware for chip
writing. Need more info.
Emulated: Unemulated.
!! COS32
Banks: 16kb main bank. The other is banked in for a short period of time (would anybody compute that for me?) by any access to $D5xx area. Also contains the button on RD4/RD5. As I have other similar COS cartridge, I seem to remember there was some kind of service/toolkit which allowed to put anything on the cart.
Emulated: Unemulated.
Great source of information about memory and cartridge mappings is in an
article by John Picken.(see Part 1!) this info (c) 1998-2002 Jindroush. Last modified: Fri Feb 22, 20:20:00 2002;
!!! Part 4: Converting games to Cartridge
by Nir Dary
(written 23/6/2001; mail: ndary@bigbart.com)
We all love cartridges some of us even collect them. They are simple and quick to load, just plug it in your computer and the game starts.
This time I would like to share my knowledge and show you all how you can
convert your favorite games to cartridges, all you need is an empty EPROM
chip, an EPROM burner, Cartridge PCB and an Assembler editor.
Before we will start to explain how to port disk/tape games lets have a few
words about cartridges...
The earlier ATARI model (800) had two 8K cartridge slots: Left and Right. The Right cartridge occupied memory address $8000 to $9FFF while the Left
cartridge occupied memory address $A000 to $BFFF. Once a cartridge is
inserted to the computer the memory address above becomes read only data. The XL/XE ATARI models are compatible with the 800 cartridges but they also have the possibility to read one 16K cartridge (that will occupy memory address $8000 to $BFFF), lets not forget the Bank Switchable cartridges, these are cartridges that contain more than 16K data, like the XEGS or OSS cartridges. The XEGS can contain up to 128K of game data i.e. 'Ace of Aces', 'Flight Simulator 2' carts etc.. Lets look at the cartridge connector:
Cartridge Slot ("Left" slot on all machines; "Right" slot on 800 only):
{{{
A B C D E F H J K L M N P R S
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1. /S4 A. RD4
2. A3 B. GND
3. A2 C. A4
4. A1 D. A5
5. A0 E. A6
6. D4 F. A7
7. D5 H. A8
8. D2 J. A9
9. D1 K. A12
10. D0 L. D3
11. D6 M. D7
12. /S5 N. A11
13. +5V P. A10
14. RD5 R. R/W
15. /CCTL S. B02
}}}
When the ATARI computer is booting, one of the first things the Operating
system is checking is cartridge presence. If a cartridge is inserted its been executed, so a cartridge can be executed even before the rest of the OS routines are finished (i.e a Diagnostic Cartridge). The Last 6 bytes of the cartridge Memory location (addresses $BFFA to $BFFF) determine the RUN/INI address of the cartridge, if to Load DOS before running the cart software? etc\x{2026}
{{{
$BFFA/$BFFB - is the cartridge start address.
$BFFC - A non-zero number here tells the OS that there is no cartridge
in the left slot
$BFFD - set to $05 if you want to boot Dos before running the cart $04
if no
$BFFE/$BFFF - Cartridge initialization address
}}}
The XEGS cartridges contain several 8K banks (depending on the cartridges size), the last bank is always shown at Memory area $A000 to $BFFF of the Atari computer while the rest of the 8K banks are mapped memory area $8000 to $9FFF depending on what value of data you set $D5XX. For example on a 64k cartridge the last 8k Bank of the cartridge (cartridge ROM memory location $E000 to $FFFF) are mapped to the XL memory location $A000 to $BFFF, and when accessing Atari location $D500 you can set which of the first seven 8K banks will be mapped to the ATARI memory location $8000 TO $9FFF.
Now lets get into business:
You cannot convert every game to a cartridge, there are limitations...
1. You must feet the game into the cartridge memory space; you can use a 16k PCB for games that are less than 16k in size, or a XEGS pcb with larger ROMs.
2. The game must load in one part (single stage - one file). If the game is loading in several stages - then without modifying the game code it will try accessing TAPE/DISK when looking for the next stage to load ***
3. The game should not try to write to the cartridge memory address. Because after you insert the cartridge this is read only memory...
4. Some games are detecting cartridge presence and when a cartridge has been inserted the game will not run; this was done to prevent from some debugging cartridges to help hacking the game code
* *** However there are some tricks to get even a multi-stage tape/disk game running from a cart (examples: Dandy, Summer Games, etc.) - but thats really a lot of work we will not explain here...
If your game is not restricted by the above limitations then we have a go.
What we will do is simply write a routine that will copy the game data from
the ATARI Cartridge Memory area back to the original game location and execute the game. This works for 90% of the games I tried !!
Next you will find a generic cartridge memory dumping routine that will work for most of the games. To explain how it works, lets take a game and make it work from a 16k cartridge PCB ("Danger Ranger" was never released on a cartridge).
Danger Ranger game loads into Memory Address: $0400 to $211F and is executed at address: $0488. The TABLE at the beginning of the source tells the copy routineto copy the Game Data from Address $A200-$BF20 To $0400-$211F. Here is the TABLE description:
{{{
Byte 0 - What 8k bank to access, to use with XEGS carts (on 16k cart
it should always be set to 00), if equal to $FF then end copy.
Byte 1,2 - Start Source address of data location on the Cartridge ROM,
(on a 16k cart pcb it will be from $8000 to $BFFF, and on an
XEGS cart from $A000 to $BFFF)
Byte 3,4 - Destination address where to copy the game data.
Byte 5,6 - Last byte of Source address to copy
}}}
!! Universal Cartrige Copy / Run routine
{{{
;Universal Cartrige Copy / Run routine
;written by Nir Dary 13/6/2001
;
;
GSA = $0488 ;Game Start Adress
DOSINI = $0C ;
DOSVEC = $0A ;
TMPFROM = $CA ;Tmp Source address
TMPTO = $CC ;Tmp Dest. address
TMPEND = $CE ;Tmp End Copy Addr
TMPTABLE = $D0 ;Table address
;
; This Routine will be located at $A000
; but Assembled at $3000 mem area
;
Org $3000
;
TABLE .BYTE $00,$00,$A2,$00,$04,$20,$BF
.BYTE $FF ;$FF ends the copy
;
START STX $03E9 ;Cassette vector -
STX $03EA ;disabled
DEX
STX $D301 ;Basic off - hardware
LDA #$01
STA $09 ;Boot? - say booted
STA $42 ;Critic set
STA $03F8 ;Basic off - software
;
;
LDA #$00 ;Short Move Routine
STA TMPTO
STA TMPFROM
STA TMPTABLE
TAY
LDA #$30 ;Copy to PAGE 30
STA TMPTO+1
STA TMPTABLE+1
LDA #$A0
STA TMPFROM+1
L1 LDA (TMPFROM),Y
STA (TMPTO),Y
INY
BNE L1
JMP COPY ;ie. jmp 3000 region to
;move code out of cart.
;
;
COPY LDA #$00 ;Enable Access to
STA $D40E ;Shadow O.S Ram
SEI
LDA #$FE
STA $D301
L2 LDY #$00 ;Load Bank# from table
;into X register
LDA (TMPTABLE),Y ;deted if End
CMP #$FF ;of Table then
BEQ EXITCOPY ;exit to run game
TAX
INC TMPTABLE
LDA (TMPTABLE),Y ;Load Source
STA TMPFROM ;Address
INC TMPTABLE
LDA (TMPTABLE),Y
STA TMPFROM+1
INC TMPTABLE
LDA (TMPTABLE),Y ;Load Dest
STA TMPTO ;Address
INC TMPTABLE
LDA (TMPTABLE),Y
STA TMPTO+1
INC TMPTABLE
LDA (TMPTABLE),Y ;Load Source
STA TMPEND ;end Address
INC TMPTABLE ;to copy
LDA (TMPTABLE),Y
STA TMPEND+1
INC TMPTABLE
;
;Start of Copy Routine
;
MAINLOOP STX $D500 ;Load Rom bank to
LDA (TMPFROM),Y
STA (TMPTO),Y
INC TMPFROM
BNE L3
INC TMPFROM+1
L3 INC TMPTO
BNE L4
INC TMPTO+1
L4 LDA TMPFROM+1
CMP TMPEND+1
BNE MAINLOOP
LDA TMPFROM
CMP TMPEND
BNE MAINLOOP
BEQ L2 ; Do next Bank?
;
EXITCOPY LDA #$22
STA $D400 ;DMA control
LDA #$FE
STA $D301 ;RAM under ROM on
LDA #$40 ;Some games need $C0
STA $D40E ;NMI allowed
CLI
LDA #<GSA
STA DOSINI
STA DOSVEC
LDA #>GSA
STA DOSINI+1
STA DOSVEC+1
;
LDA #$C0 ;C000 high byte
STA $2E4 ;system size
STA $2E6 ;
STA $6A ;dlist ends a
;
LDA #$00 ;cart interlock
; STA $03FA ;no cart status = off
STA $42 ;critic OK
STA $244 ;COLDST
LDA #$01
STA $08 ;WARMST
TAY
CLC
JMP GSA ;$E474
RTS
;
;Cartrige Run Address
;See Mapping the Atari
;
Org $BFFA
.WORD $0000
.BYTE $00
.BYTE $04
.WORD START+$7000
}}}
Once you assembled this routine make sure you add the game data to the correct source location. With this doc you will find a ready made ROM file of Danger Ranger game, simply burn the ROM data into a 27C64 (8k) EPROM, and insert it on the Right slot of a 16k cartridge pcb, (try the 16k Cartridges PCB from B&C computer visions or Best Electronics).
NIR DARY