Just a few notes about the Miniassembler and the 65C02 opcodes support in the different Apple ][ models.
The Miniassembler (the thing with the "!" prompt you use to assemble programs from the command line) appeared at first in the original Apple ][ ROM in 1977. Back then, you had to type F666G from the Monitor or CALL -2458 from BASIC to enter it. I believe you had to type Ctrl-C (and not just Return) to get out of it. The Miniassembler was shifted out of the Apple ][+ to make room for the new Appplesoft BASIC. There are, from then, three models that don't have the Miniassembler: the ][+, the original (unenhanced) //e, and the original (16 Kb ROM, no 3.5" support) //c. The following model, the Apple //e Enhanced, included again the Miniassembler, this time being easier to call: you just had to type "!" at the Monitor's command prompt to enter it. All the later models (the later revisions of the //c -3.5" drive support with 32 Kb ROM and memory expansion //c-, all //gs, the Platinum //e and the //c+) maintain it in the same way as in the //e Enhanced. There are several Apple ][ models that support the 65C02-specific opcodes: all the revisions of the //c, the //c+ and the //gs. Obviously, as the original //c don't have the Miniassembler, it only supports them in Monitor's dissasembles (L command). As far as I know, the Apple //e never supported the 65C02 opcodes, neither did the Apple //gs with the 65816-specific opcodes or 16-bit code. One more note: if you're going to use the Miniassembler, take into account that every line entered (except the first) should start with an space, as pictured in Steve Conrad's e-mail. Greetings, Antonio Rodr�guez (Grijan) <ftp://grijan.cjb.net:21000/> Steve Conrad ha escrito: > >From a BBS I am on > > Jun 15, 2003 14:54 from Scalar > > The Apple II series has assembly programming built into the system ROM. > > In all version of the ROM, the monitor provides a "disassembler", which will > take an arbitrary bank of memory and attempt to spit it out as assembly code. > This is the "L" command in the system monitor. > > In the Applesoft/Floating point Apples (all Apple IIe and onward, later II+ > models) there is also a built-in code assembler, accessible with the "!" > command in the monitor. > > Note that that later IIe could be "enhanced" with a revision upgrade of the CPU > from "6502" to "65C02" which are functionally identical but the 65C02 > supporting some additional opcodes. These opcodes are not known to the built-in > assembler/disassembler in the enhanced IIe. (Don't know if a IIc or IIgs will > display them.) > > Getting to the disassembler/assember: > > >From basic, enter the monitor with the command "CALL-151" > > ]CALL -151 > > * > > At the monitor prompt type a memory address and an "L" to dump that region as > assembly code. It will disassemble as much as will fit the screen, so the data > amount varies with the length of the opcodes. > > *F800L > > F800- 4A LSR > F801- 08 PHP > F802- 20 47 F8 JSR $F847 > F805- 28 PLA > F806- A9 0F LDA #$0F > F808- 90 02 BCC $F80C > F80A- 69 E0 ADC #$E0 > F80C- 85 2E STA $2E > F80E- B1 26 LDA ($26),Y > F810- 45 30 EOR $30 > F812- 25 2E AND $23 > F814- 51 26 EOR ($26),Y > F816- 91 26 STA ($26),Y > F818- 60 RTS > F819- 20 00 F8 JSR $F800 > F81C- C4 2C CPY $2C > F81E- B0 11 BCS $F831 > F820- C8 INY > F821- 20 0E F8 JSR $F8OE > F824- 90 F6 BCC $F81C > * > > It will attempt to disassemble any type of data, and cannot distinguish between > non-machine code and real code. In fact if you give it the wrong starting > address (F801L rather than F800L) it will not know the difference and you'll > possibly see what looks like valid assembly but is in fact completely wrong. > It'll spit out wrong data until there's an error and it prints ??? or BRK until > the data is good again. > > To access the assembler, just type "!" on a monitor line by itself. > > *! > > ! > > To start assembling, specify the starting memory range and a colon followed by > the first opcode. To keep on assembling, start each line with a space followed > by the opcode. To finish, type return on a line by itself to exit the > assembler. Here's a very simple program I just made up to fill a bank of memory > with 256 copies of the number 3: > > !300:LDY #0 > ! LDA #3 > ! STA $2000,Y > ! INY > ! CPY #0 > ! BNE 304 > ! RTS > ! > > * > > As you type each line, it will be replaced with the assembled code. > > !300:LDY #0 > > is replaced by > > 0300- A0 00 LDY #00 > > Note that I did not know the branch target address for BNE UNTIL I had entered > the code. This is one of the big limitations of this built-in assembler. It > cannot calculate the address of branching for you. For larger handwritten > programs like this, sometimes the branch is entered invalid and then you go > back and fix it once the code is fleshed out and the target address can be > known. > > This is purely a line-editor assembler, and can only encode what you tell it. > If you don't know the branch target yourself, the built-in Apple II assembler > cannot help you. > > If you want a better assembler, you need a product like MERLIN, which offers a > word-processor environment to edit the code, along with the ability to used > labels to mark branches. This way you can designate a spot in the code as a > branch target, and the MERLIN assembler will automatically determine the target > address for you when you are done and compile the code. > > MERLIN also supports labeling commonly-used data locations, so that you can use > a common name rather than direct addresses which may mean nothing to the > beginner at assembly. > > A third benefit of an assembly-language compiler is something called "memory > portability". The branch opcodes are location independant, and the programming > code can be used anywhere in memory and still run properly. However branch > codes can only run code 128 bytes forward or back from the current location. > branching further requires a JMP command. > > JMP is an absolute address, and the target address of a JMP will not change if > the program is moved in memory. A program written for the 0300-03CF memory > block that uses a JMP will crash if you relocate it to 2000-20CF and try to run > it there. If written by hand, you'd have to manually re-edit the code to redo > the JMP's so they will point to valid machine code in the new memory range. > > With MERLIN, you can change the address where the code is to be run, and when > compiled MERLIN will automatically retarget all the JMP's so that the program > will still work when run in a different section of memory. > > [Antique And Older Computers> msg #24007 > > Steve Conrad > 810 Main > Henrietta, MO 64036 > 816-494-5692 http://sasha91.0pi.com > www.fortunecity.com/rivendell/stonekeep/600 > > It is no secret (nor should it come as any surprise) that humankind's > most noble impulses often surface during the most trying of times, that > human spirit rises to the challenge when faced with adversity, that human > strength is born from human failings...Is it any wonder, then, that the > SDF-1 crew became a tighter family after the fortress had been exiled than > it had before? > > From the log of Captain (later Admiral) Henry Gloval > > -- > Apple2list is sponsored by <http://lowendmac.com/> and... > > / Buy books, CDs, videos, and more from Amazon.com \ > / <http://www.amazon.com/exec/obidos/redirect-home/lowendmac> \ > > Support Low End Mac <http://lowendmac.com/lists/support.html> > > Apple2list info: <http://lowendmac.com/lists/apple2.html> > --> AOL users, remove "mailto:"; > Send list messages to: <mailto:[EMAIL PROTECTED]> > To unsubscribe, email: <mailto:[EMAIL PROTECTED]> > For digest mode, email: <mailto:[EMAIL PROTECTED]> > Subscription questions: <mailto:[EMAIL PROTECTED]> > Archive: <http://www.mail-archive.com/apple2list%40mail.maclaunch.com/> > > Using a Mac? Free email & more at Applelinks! http://www.applelinks.com -- Apple2list is sponsored by <http://lowendmac.com/> and... / Buy books, CDs, videos, and more from Amazon.com \ / <http://www.amazon.com/exec/obidos/redirect-home/lowendmac> \ Support Low End Mac <http://lowendmac.com/lists/support.html> Apple2list info: <http://lowendmac.com/lists/apple2.html> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/apple2list%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
