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...
by John Picken
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.
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.
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
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.
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).
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 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.
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:
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
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) -
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
by Jindrich Kubec
(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)
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.
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
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: 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
Emulated: Atari800 - read only is enough.
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
Contains:
Does change game on each reboot (binary counter powered by capacitors). Emulated: Unemulated (not needed).
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.
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,XTogether 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 no.5
Emulated: Atari800
Bounty Bob
Emulated: Atari800, BBEmu (Bounty-Bob Emu!)
Emulated: Unemulated.
Emulated: Unemulated.
Emulated: Unemulated.
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: ?
Emulated: Unemulated.
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;
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
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
;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