๐Ÿ‡บ๐Ÿ‡ธ Osborne 1: Part 7 (Double Density Disk Upgrade) [TCE #0530]

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Australia The Clueless Engineer
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Published on ● Video Link: https://www.youtube.com/watch?v=hzUkDH1IG1k


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The Osborne Model 1 supported only Single Density (SD) disks initially ... ten 256 byte sectors per track, yielding 92KB of formatted capacity per disk. An upgrade daughterboard become available which allowed Double Density (DD) support ... five 1025 byte sectors, yielding 184KB formatted capacity per disk. The drives remained Single Sided (SS) with 40 tracks per disk.

00:00 ... Start
04:00 ... The DD upgrade daughterboard
05:25 ... Replacing my original motherboard
07:45 ... Using OZROM to test RAM on new motherboard
08:40 ... Booting on a DD disk image
10:25 ... Trying PACMANOS from a DD disk image
12:25 ... Trying INVADERS
14:45 ... Trying plain-text version of HITCHHIKER'S GUIDE TO THE GALAXY
18:10 ... Briefly trying ANSI version (?) of HHGTG
19:20 ... Very briefly trying CHESS
20:30 ... Trying to format a physical floppy using the COPY program
23:20 ... Channel outro/thanks

Unfortunately it's not really possible to tell from the outside whether a particular Model 1 has this board. Double Density support was added with BIOS ROM version 1.4 so if the machine has on older ROM version (i.e. photo shows the powered-on screen) then it likely doesn't support DD disks. But, there is no guarantee that a machine displaying version 1.4 or higher has the daughterboard, either.

Nathaniel Roach's reproduction DD board:
https://gitlab.com/NRoach44/occ1-dd-upgrade

VCFED Forum post:
https://forum.vcfed.org/index.php?threads/reproduction-osborne-1-dd-upgrade-card.1239167/

My Osborne 1 Github:
https://github.com/0ddjob/Osborne_1

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