Setname:  osborne1   
Year: 1981
Manufacturer: Osborne
Status: good  works
Type: Laptop / Portable
Emulation info
Overall emulation:  good   
Color emulation:  good  
Sound emulation:  good  
Graphics emulation:  good  
Savestates:  unsupported   

Tech info
 Base hardware: (available in all slot configurations)
Z80 ("maincpu")cpu 3993600 Hz
Speaker ("mono")audio
Beep ("beeper")audio
Screen ("screen")raster horizontal 416 x 240 @ 60.000000
Media devices
Media devices for this system
depend on the chosen expansions
BIOS options
ver144 BIOS version 1.44
verA BIOS version A
ver12 BIOS version 1.2
ver121 BIOS version 1.2.1
ver13 BIOS version 1.3
ver14 BISO version 1.4
ver143 BIOS version 1.43
RAM options
68K 69632
Software lists

 Optional hardware: (available with specific slot configurations)

 Configure the slot options for osborne1:
 Slot Value

Show detailed info about 'DipSwitches' of this system

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Show detailed info about 'Slot Options' of this system
Slot options

NameValueCompatible device(s)
mb8877:0 525ssdd floppy_525_ssdd
mb8877:1 525ssdd floppy_525_ssdd

Romset info
ROM NameSizeCRC32SHA1Dump StateBIOS option
7a3007-00.ud152048 6c1eab0db04459d377a70abc9155a5486003cb795342c801good
osb12.bin4096 nodumpver12
osb121.bin4096 nodumpver121
osb13.bin4096 nodumpver13
rev1.40.ud114096 3d9663350c60b97a3154a75868efc6370d26995eadc7d927goodver14
rev1.43.ud114096 91a48e3cc37b83f278d21e6e92d80f9c057b11f7f22d88d4goodver143
3a10082-00rev-e.ud114096 c0596b14ee6a9cc9be3ddc5949d3379351c1d58a175ce9acgoodver144
osba.bin4096 nodumpverA


* CPU: Zilog Z80A 4 MHz
* RAM: 64 KB
* ROM: 4 KB
* Text Modes: 52 / 80 / 104 char. x 24 lines
* Graphic Modes: Only graphic characters
* Colors: Monochrome
* Sound: Beeper
* I/O Ports: RS232, IEEE 488, Modem port, Composite Video
* Keyboard: Full-stroke keyboard with separated numeric keypad
* Built In Media: 2 x 5.25" FDD
* OS: CP/M
* Built In Language: None, but it was supplied with : CBasic, WordStar, SuperCalc, MailMerge, DBase II.


MESS currently supports Osborne-1 with up to two floppy drives, "floppydisk1" (flop1) and "floppydisk2" (flop2), for disk images in .img format.


This system requires 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 "Scroll Lock" key (by default).

History and Trivia

The Osborne 1 is one of the first portable computers but needs external power source. Its name comes from Adam Osborne, the man who made this computer a reality (not quite true, see end of the text).

It has a very small built-in screen (8.75 x 6.6 cm, which can display 128 columns!!) and weighs more than 10 Kg.
The first models couldn't display more than 52 columns by line, so to access to the 76 other columns, the user had to scroll among the screen thanks to the cursor keys.

It works under CP/M and was sold with Digital Research CBASIC (compiled BASIC), SuperCalc (spreadsheet), WordStar (word processor), MailMerge (mailing) and Microsoft's MBasic (MBasic source code was 100% upwards compatible with IBM PC's BASICA, source code only).

This machine would be succeeded in 1983 by the Osborne Executive, which featured a larger screen and lower-profile disk drives.

Despite its interesting characteristics, Osborne Computer Corporation suffered the competition of the first IBM PC compatibles and went bankrupt in 1983. One casualty was a planned portable computer called the Osborne PC (which, interestingly, was an MS-DOS clone). It was never released (even though prototypes exist).

(info from old-computer.com)


* Dave Mathews's Osborne O1 page -- http://www.davemathews.com/osborne.html
* Osborne 1 at old-computers.com -- http://www.old-computers.com/museum/computer.asp?c=181

Edit the History info for this game.


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