Recently added features

The MEGA65 batch #1 shipped from the factory with ROM version 920287 (release 0.9) and a User’s Guide printed in late 2021. Batch #2 shipped in late 2022 with ROM version 920377 (release 0.95). MEGA65s will continue to ship with the first printing of the User’s Guide until stock is exhausted. Meanwhile, the ROM is considered a work in progress, and the MEGA65 team and contributors continue to enhance it with bug fixes and other improvements.

Below is an incomplete list of features that have been added since the first release. I can’t possibly keep this list up to date, but I wanted to describe a few so you know what you’re getting with the updates. I’m leaving out the many bug fixes, which are valuable in their own right. See the ROM change log and the core change log for a complete list of changes across the versions.

MEGA65 documentation writers are keeping the downloadable PDF version of the User’s Guide up to date with new features. Be sure to download this along with ROM updates.

New features

Some of the new features that have been added in the last couple of years:

  • Holding RUN/STOP during boot immediately enters the machine language MONITOR.

  • Filename pattern matching supports # to match a single number character, and $ to match a single letter character: DIR "ME$$*"

  • To toggle between 40-column mode and 80-column mode, press ESC then press X. To go directly to 40-column mode, use ESC then 4. To go directly to 80-column mode, use ESC then 8.

  • BASIC supports arithmetic shift operators: << and >>. PRINT 7<<3

  • Single-letter BASIC variables are “fast” variables stored in fixed memory addresses $FD00-$FEFF.

  • The PLAY and SOUND commands have improved background playback and use of SID voices, so BASIC games can sensibly have both background music and sound effects.

  • Some disk commands can access files on the SD card directly (and not via a mounted D81 disk image) using the virtual device U12. DIR U12 lists the files on the SD card. DLOAD "FILE.PRG",U12 loads a PRG file.

  • BASIC programs can access screen and color memory via special byte arrays T@&(COLUMN, ROW) and C@&(COLUMN, ROW). Screen coordinates are intuitive in both 40-column and 80-column modes.

  • If you accidentally hit the HOME key, you can press ESC then HOME to return the cursor to its original position.

  • You can load a program from disk by using DIR to view the directory listing, moving the cursor to the program name, pressing / (forward slash), then pressing Return. You can load and run a program in a single step using the ↑ (up-arrow) character (next to the Restore key) in the same way.

  • Ethernet file transfer support; use the new M65Connect app (or command line tools), and see the User’s Guide, 2nd edition, for instructions

  • New core selection and flashing menu, capable of flashing slot 0 without a JTAG adapter

    • Can configure core slots to be selected automatically when different types of cartridges are connected, so a C64 cart can auto-boot into the C64 core instead of the MEGA65 core

    • Core file selector supports long filenames

  • New hardware typing event queue, enables faster and more accurate typing

  • Improvements to the chipset, Freezer, SD card utility, and Configuration utility

    • Fixed mouse handling in port 2

    • Configuration utility now prompts to power cycle on exit, to avoid confusion

  • Screen editor and KERNAL use the new hardware typing event queue, for faster and more accurate typing

  • 80 x 50 text mode: press ESC then 5 (press ESC then 8 or 4 to select 80x25 and 40x25)

  • Default sprite images, including a mouse pointer in sprite slot 0

  • GO64 mode now displays a custom banner instead of the C64 banner, so it’s easier to distinguish between GO64 mode and the C64 core

  • Support for booting MEGA65 cartridges, based on the MEGA65 cartridge protocol

  • Run/Stop-Restore now restores the character set

  • Improvements to the Monitor, Renumber, BASIC commands, DOS

New BASIC commands

Many new BASIC commands have been added to the factory-installed ROM, or have been added to the User’s Guide since it was printed. See the latest User’s Guide for specifics. New commands include:

Disk commands

MOUNT controls the mounting of disk images and drives to the unit numbers from BASIC, without having to enter the Freezer.

  • To mount a D81 disk image from the SD card to unit 8: MOUNT "FILENAME.D81"

  • To mount the built-in physical 3-1/2” disk drive: MOUNT

FORMAT formats (erases) a mounted disk. This is an alias for HEADER.

  • To prepare a new disk in unit 8 for use: FORMAT "DISKNAME",I01

  • To quick-erase a previously prepared disk in unit 8: FORMAT "DISKNAME"

CHDIR and MKDIR support sub-directories on D81 disks and the SD card.

  • To change to a sub-directory of the current directory on unit 8: CHDIR "SUBDIR"

  • To return to the root directory on unit 8: CHDIR "/"

  • To make a sub-directory on unit 8: MKDIR "SUBDIR"

  • To change to a sub-directory on the SD card: CHDIR "SUBDIR",U12

  • To change to the parent directory of the current directory (SD card only): CHDIR "..",U12

LOCK and UNLOCK set the status of a file on disk so that it cannot be deleted when locked.

  • To lock a file on unit 8: LOCK "FILENAME"

  • To unlock a file on unit 8: UNLOCK "FILENAME"

IMPORT takes a SEQ file of PETSCII text as if typed into the BASIC editor. Unnumbered lines are ignored: it does not run commands in immediate mode.

  • To import a text file as BASIC: IMPORT "LISTING"

    • Any BASIC program already in memory will remain in memory, with only the lines in the listing overwriting what is already there. This makes IMPORT useful for adding a file of common routines to an existing program.

  • To export the current BASIC program as a text file that can be imported: DOPEN#1,"LISTING",W:CMD 1:LIST:DCLOSE#1

    • Every command that outputs text between CMD 1 and DCLOSE#1 writes to the file. For example, you can add arguments to LIST to only export a portion of a program: LIST 2000-2999

Graphics commands

CUT, GCOPY, PASTE act on a rectangle of a graphics screen as a clipboard. GCOPY copies a rectangle of pixels to a buffer; CUT copies the rectangle then fills with the color of the pen. PASTE paints the previously copied rectangle onto the screen at a given location. An example from the manual:

10 SCREEN 320,200,2
20 BOX 60,60,300,180,1
30 PEN 2
40 CUT 140,80,40,40
50 PASTE 10,10,40,40
60 GETKEY A$
70 SCREEN CLOSE

DOT draws a single pixel on a graphics screen.

10 SCREEN 320,200,5
20 DOT 100, 80, 7
30 GETKEY A$
40 SCREEN CLOSE

CHARDEF changes the image for a single character based on its arguments. This makes it easy to produce custom fonts or character graphics in a BASIC program.

  • To replace the letter A with a happy face:

CHARDEF 1,$3C,$7E,$DB,$FF,$BD,$C3,$7E,$3C

  • To restore the PETSCII font: FONT C

VSYNC <n> waits until screen drawing reaches raster line n. This is useful for games and graphical demos that need code to run once per frame for smooth animation or effects. This was once only possible with machine language programs, but MEGA65 in 40 MHz mode runs BASIC quickly enough for high speed games.

10 BORDER 0: VSYNC 150: BORDER 1: VSYNC 180: GOTO 10

Memory commands

MEM reserves 8K segments of memory in banks 4 and 5 for use by the program, such that the graphics library does not use them.

  • To reserve $40000-$41FFF for program use: MEM 1,0

SETBIT and CLRBIT set and clear a given bit at a given byte memory location. Bit numbers are 0-7 from least significant to most significant.

  • Given address $03FFF containing the bit pattern 00110111 ($37), to set bit 6 so it becomes 0110111 ($77): SETBIT $03FFF, 6

WPOKE and WPEEK() write and read, respectively, a 16-bit (“word”) value at two consecutive locations in memory, least significant byte first.

  • To store the word $FABC across byte addresses $0C000 (the least significant byte $BC) and $0C001 (the most significant byte $FA): BANK 0 : WPOKE $C000,$FABC

  • To read the 16-bit value stored at $0C000-$0C001: V = WPEEK($C000)

Other BASIC features

The FREEZER command opens the Freeze menu, as if you pressed Restore for a second.

The INFO command prints useful information about the system and available BASIC memory.