Restoring my BBC Model B Micro

RESTORING MY BBC MODEL B MICRO Ben Charlton twitter.com/bencc

My BBC Model B Released in 1981, I think mine was made in ‘82.

My BBC Model B

My BBC Model B Released in 1981, I think mine was made in ‘82. Issue 3 board, first significant production run. Issue 4 and 7 boards most common. Given it in ~1990 (I was 9-ish) Actively used until 1995. Big part of my childhood. Stored in lofts and damp garages until early this year. Last tested ~7 years ago when I collected it from my parents.

Accessories ■ I’ve also got: – Proper Microvitec CUB monitor – Dual 5¼ floppy drives – Joysticks – Lightpen – Beebcalc spreadsheet ROM – Wordwise word processor ROM – Books!

Specifications ■ 32 Kb RAM ■ 2 MHz 6502 processor

Specifications

Specifications ■ 32 Kb RAM ■ 2 MHz 6502 processor ■ 640×256, 16 colour (but not at the same time!) graphics ■ 4 channel TI audio chip (as used in many arcade games and SEGA console) ■ Tape interface ■ Floppy disk controller - Intel 8271

Specifications ■ 32 Kb RAM ■ 2 MHz 6502 processor ■ 640×256, 16 colour (but not at the same time!) graphics ■ 4 channel TI audio chip (as used in many arcade games and SEGA console) ■ Tape interface ■ Floppy disk controller - Intel 8271 ■ The BEST ’80s home computer keyboard.

Specifications ■ 32 Kb RAM ■ 2 MHz 6502 processor ■ 640×256, 16 colour (but not at the same time!) graphics ■ 4 channel TI audio chip (as used in many arcade games and SEGA console) ■ Tape interface ■ Floppy disk controller - Intel 8271 ■ The BEST ’80s home computer keyboard. ■ Notorious for power supply failures after ~30 years!

Power Supply Fix

IT’S ALIVE (sort of)

Rubbish crimping L

IT’S ALIVE!

Modern Storage

Software recovery

Software recovery ■ 5¼” single density disks, ”FM” encoded. ■ 256 bytes per sector ■ 10 sectors per track ■ 40 or 80 tracks per side ■ 100 or 200 kB.

Software recovery ■ 5¼” single density disks, ”FM” encoded. ■ 256 bytes per sector ■ 10 sectors per track ■ 40 or 80 tracks per side ■ 100 or 200 kB. ■ Treasure Island by Robert Louis Stevenson is 387 kB ■ Tolstoy’s War and Peace is 3200kB.

Kryoflux!

Kryoflux ■ USB2 to ‘Shugart interface’ floppy adaptor ■ Works with 5¼”, and 3½”, and even 8” drives. ■ Reads the raw magnetic flux of the disk, doesn’t care about formatting. ■ Later software process constructs a valid floppy image. ■ https://www.kryoflux.com/

Kryoflux ■ USB2 to ‘Shugart interface’ floppy adaptor ■ Works with 5¼”, and 3½”, and even 8” drives. ■ Reads the raw magnetic flux of the disk, doesn’t care about formatting. ■ Later software process constructs a valid floppy image. ■ https://www.kryoflux.com/ ■ Can reveal old data on the disks!

Kryoflux

Floppy drives

Shugart Associates ■ 1973 Alan Shugart starts Shugart Associates, to build a small business computer. ■ 1974 Run out of money to finish, switches to just selling storage. Alan Shugart resigns as CEO ■ 1976 Releases 5 ¼ inch ‘minifloppy’. ■ 1977 Sold to Xerox ■ 1979 Invented ‘Shugart Associates System Interface’ which eventually became SCSI.

Shugart Associates ■ 1973 Alan Shugart starts Shugart Associates, to build a small business computer. ■ 1974 Run out of money to finish, switches to just selling storage. Alan Shugart resigns as CEO ■ 1976 Releases 5 ¼ inch ‘minifloppy’. ■ 1977 Sold to Xerox ■ 1979 Invented ‘Shugart Associates System Interface’ which eventually became SCSI. ■ 1979 Alan Shugart forms Shugart Technology in 1979, sued by Xerox. Renamed company to Seagate Technology.

82 disks later…

82 disks later… ■ 2.34 GB of data ■ 20 - 35MB of “flux” data per disk ■ Converts to 200 – 720 kB of disk image ■ Mix of BBC B, PC and Xenix disks.

5¼ disk image on 4GB SD card…

Cleaning!

The future? ■ It’s been nice to play with the real thing again. ■ BBC B going back in the loft. ■ I love it, but emulation and modern screens a much nicer experience.

Useful ■ SD card adaptor – RetroClinic on ebay. ■ Stairway to Hell collection - https://www.stairwaytohell.com/ ■ BeebEm - http://www.mkw.me.uk/beebem/ ■ http://bbcmicro.co.uk/