version.txt

emulator of an 8086 microprocessor

emu8086

The Microprocessor Emulator of 8086 Microprocessor (Intel and AMD compatible)
And Integrated 8086 Assembler + Flat Assembler (FASM)



Version 4.04
======================

Support added for the original MASM-16 assembler from Microsoft.

#masm# directive should be used to invoke original MASM assembler.

EMU8086 integrated assembler has similar to MASM syntax, but
may not be compatible with all of its advanced macro features.

"MASM_PATH" must be set in emu8086.ini to point at MASM working directory.
By default: C:\MASM611\ 

Please note: MASM assembler is not included in EMU8086 pack, it should
be acquired separately from Microsoft. MASM installation is not required
unless you need 100% compatibility or faster assembling speeds.

In addition, a minor bug with showing incorrect variable values
for specific code combinations, is fixed for FASM assembler.


Version 4.03
============

To turn off strict syntax checking set "STRICT_SYNTAX=false" in 
c:\emu8086\emu8086.ini (line 62), in this version the strict
syntax option is turned on by default.

Minor bug with address calculation is fixed.

Drag & drop bug is fixed for filenames containing spaces.


Version 4.02
============

The step-back button allows to execute instructions backwards.

Font size of logical flag analyser can be modified in emu8086.ini

The keyboard buffer is now visible and can be flushed with a click.

It's possible to use _ to separate nibbles of long binary values,
for example:      mov ax, 1000_0011_0001_1111b

All devices are external, source codes of the devices can be found
in this folder c:\emu8086\devices\developer\

All ports from 0 to 65535 are free for custom i/o devices.

All devices must be recompiled with new location of IO file.
new location is: c:\emu8086.io 

Default code templates can be customised in c:\emu8086\inc 

External button loads windows debug.exe after the compilation.

Default fonts for memory, emulator screen and disassembly
are changed to Terminal, if your system does not have an appropriate
Terminal font you can set it back to Fixedsys from options.

Far call is supported, see examples: far_call.asm and far_call_advanced.asm

Default output type for boot records is now .bin -- .boot output type
is obsolete. .binf file has the information required for the emulator
to know the loading prefix, for boot record it is 0000:7c00 (CS=0, IP=7c00).
if there is no .binf file associated with .bin file, then default.binf
is used by the emulator to determine where to load the binary file.

Recent files menu is not reset with other options.

More ASCII extensions can be added to emu8086.ini, files that are
considered ASCII are loaded into the source editor rather than the emulator.

c:\emu8086\FLOPPY_0 - virtual floppy drive is empty by default,
previously it was pre-loaded with micro operating system example.

Command prompt can be launched in output folder right after the compilation,
or from emulator's view menu.

SEG directive returns cs when there are no defined segments.
assembler automatically replaces code like this: mov dx, seg var1
with this: mov dx, cs

There is no practical use for this when compiling tiny and simple .com file,
because it usually has only one segment and can relocate itself without
the need of relocation tables.

New interrupt function available INT 21h/43h - get/set file attributes.
example is in c:\emu8086\examples\attrib.asm 

mov dx, offset file ; zero terminated file name.
mov ah, 43h

mov al, 0  ; get attributes.
mov al, 1  ; set attributes.

; cx - attributes:

 mov cx, 0       ;  normal - no attributes.
 mov cx, 1       ;  read-only.
 mov cx, 2       ;  hidden.
 mov cx, 4       ;  system
 mov cx, 7       ;  hidden, system & read-only.

Interrupt documentation is only partly updated, 
this function is not documented yet, but there is
an example in c:\emu8086\examples\attrib.asm 
note: it may look like the file suddenly disappears unless you set 
the settings of file manager to show system and hidden files.

Programs can be started in real environment - external button and menu.

OUT instruction can be undone with step-back as well.

Moving cars added to traffic lights device, example: traffic_lights.asm

Automatic workaround for short relative jumps updated, to overcome
jump limit of +/-127 bytes, short conditional jumps are replaced
with the opposite instruction and one normal jump, then cpu just either 
skips over normal jump, if original condition is false, or doesn't if
original condition is true. for more information refer to tutorial 7.

WRITEBIN.ASM utility is updated, this little program can be used to 
write bin file to boot record of a floppy drive and make it bootable.
now it's possible to write a complete micro-operating system on a floppy
drive. to use this utility you need to compile it first. it works from
command line. to write a boot record type this:
		writebin loader.bin
to write kernel type this:
		writebin kernel.bin /k
this utility should be used with micro-operating system example:
   micro-os_loader.asm       and       micro-os_kernel.asm
however, it is not limited to these files and can be used with other
files, for example it can be used to test timer.asm as well.

Double word definition is supported:

mydoubles dd 12345678h

; it is equal to:

mywords   dw 5678h
          dw 1234h

;  or

mybytes   db  78h
          db  56h
          db  34h
          db  12h

; exactly 32 bits
binn dd 00010010001101000101011001111000b
; load double word to dx:ax
mov ax, binn
mov dx, [binn+2]

Default vdrive path can be changed in emu8086.ini

Long jump is supported, for example:

	jmp far addr

	addr dd 1235:5124h

Most of the file operations can be undone with step back.
all file write operations are undone when file open function is undone.
byte-by-byte undo is not allowed.

Major mouse driver interrupts are implemented.
see mouse.asm and mouse2.asm in c:\emu8086\examples.

New example of a simplest virtual device in pure assembly language is created.
see simplest.asm in examples.

New directive added:
#start=mydevice.exe#
the emulator starts the specified executable from c:\emu8086\devices\ folder
when this directive is found in the original source code. 
previous method of searching filenames in comments is obsolete.

External debug.exe can be easily launched by F12 hotkey.
it can be used along with the log button to check validity of the emulator if results are disputable.
hotkey for the emulator's log button is F11.

Hardware interrupts are enabled.
when interrupt flag is 1, the emulator continually checks first 256 bytes of this file c:\emu8086.hw
if any of the bytes is none-zero the microprocessor transfers control
to an interrupt handler that matches the trigerring byte offset in emu8086.hw file (0 to 255)
according to the interrupt vector table (memory 0000-0400h) and resets the byte in emu8086.hw to 00.

Tab codes (9) are expanded as specified by ascii standard.
The bell code (7) produces a short beep. for example:
mov al, 7
mov ah, 0eh
int 10h

The startup window can be turned off/on from emu8086.ini

"#mem=..." directive can be used to write values to memory before program starts
(for .bin files that run in the emulator only).