• CPU: 6502 1 MHz
• RAM: 4 KB (early version) then 8 KB
• VRAM: 1 KB
• ROM: 14 KB
• Text Modes: 40 x 25
• Graphic Modes: None
• Colors: Monochrome
• I/O Ports: IEEE 488, Parallel port, second, “user port” for 8-bit I/O, cassette port inside the case, rarely used
• Keyboard: 73 key 'chicklet' keyboard with numeric keypad
• Built In Language: Commodore Basic 1.0
• Built In Media: tape recorder

MESS emulates the following computers

• pet2001 [PET 2001]
• pet2001b [PET 2001-B]
• pet2001n [PET 2001-N]
• cbm30 [Commodore 30xx]
• cbm30b [Commodore 30xx (Business Keyboard)]
• cbm30nor [Commodore 30xx (Norway, Business Keyboard)]

For each systems, MESS supports

1. two datasettes, using “cassette1” (cass1) and “cassette2” (cass2) devices, for tapes in .tap and .wav format (currently not working)
2. two cart slots, “cartridge1” (cart1) and “cartridge2” (cart2), for cart dumps in .crt, .a0 and .b0 format
3. two floppy drives, “floppydisk1” (flop1) and “floppydisk2” (flop2), for disk images in .d64 format.

Also notice that a “quickload” (quik) feature is available for .p00 and .prg files.

To load a directory of available files you can use

LOAD"$"[,<devicenumber>]

i.e. to see what is on a disk (device number=8) type

LOAD"$",8

to see what is on a tape type (default)

LOAD"$"

To load a file into memory from an external device

LOAD"<filename>"[,<devicenumber>]

To run the file currently in memory type

RUN

Since the diskdrive is device number 8, you have to use

LOAD"<filename>",8

e.g.

LOAD"PACMAN",8

Since the tape drive is the default device, you can simply use

LOAD"<filename>"

e.g. LOAD”PACMAN”

These systems require full keyboard emulation to work correctly. At startup, full keyboard emulation mode is enabled by default. Whilst in full keyboard emulation mode, some key associated functionality may be disabled (like the Esc key for EXIT). The keyboard emulation mode is toggled using the Scrl Lock key (by default).

Original Keyboard (pet2001): 73 key 'chicklet' keyboard with numeric keypad

CLR CRSR CRSR INST
 @    !    "    #    $    %    '    &    \    (    )    <-    [    ]          HOME  U/D  L/R  DEL
 
RVS
OFF     Q    W    E    R    T     Y    U    I    O    P    UP   <    >          7    8    9    /

 SHIFT                                                      STOP
 LOCK     A    S    D    F     G     H    J    K    L   :   RUN  RETURN         4    5    6    *
 
 																				
  SHIFT     Z    X    C    V    B     N    M     ,    ;   ?    SHIFT            1    2    3    +
 
 
                                SPACEBAR                                        0    .    -    =

Original Keyboard (pet2001n, pet2001b, cbm30xx): QWERTY full-stroke keyboard, and sometimes calculator type

CRSR  STOP
    <-   1!   2"   3#   4$   5%   6&   7'   8(   9)   0     :*   -=   UP    L/R   RUN           7   8   9

                                                                        CRSR    DEL
    TAB    Q    W    E    R    T     Y    U    I    O    P    [    \    U/D    INST             4   5   6

	 SHIFT
ESC   LOCK   A    S    D    F     G     H    J    K    L   ;+    @     ]      RETURN            1   2   3

RVS                                                                                HOME
OFF   SHIFT     Z    X    C    V    B     N    M    ,<   .>   /?   SHIFT   REPEAT   CLR           0     .


                                   SPACEBAR

Different RAM configurations are possible for most of these systems in MESS. You can switch between them, changing the -ramsize parameter. At command line, you simply have to add -ramsize ram_value, where ram_value can assume one of the following values

• [pet2001]

4k
8k

• [pet2001n/pet2001b/cbm30/cbm30b/cbm30nor]

8k
16k
32k (default)

• Cassette emulation is not working
• I can't get programs to load from disk
• Writing and executing programs in memory seems to work

The name PET, besides being a marketing ploy to imply a user-friendly machine, is an acronym for “Personal Electronic Translator”.

The Commodore PET 2001 was a great success. Three models were made : the PET 2001-8N with 8 KB RAM, PET 2001-16N with 16 KB RAM and the PET 2001-32N. They were conceived by Chuck Peddle who later founded Tandon, a drive manufacturer.

The CBM 3xxx and 4xxx series were revisions of the original PET 2001. The range was rebranded CBM (Commodore Business Machine), as PET was dropped.

The 3xxx series introduced the 3000 series ROM sets, BASIC v3, and a completely redesigned keyboard layout, which used a full typewriter keyboard instead of the “mickey mouse” keyboard of the PET, and dropped the on-board cassette unit.

(info from old-computers.com)

• PET Index
• Larry's PET/CBM Pages
• PDF's of manuals
• PET at vintage-computer.com
• PET at old-computers.com
• CBM 30xx at old-computers.com

• VICE