New Acquisition: Acorn BBC Master 128 - 01-ANB15-0043217

Make	Model	Serial Number
Acorn Computers	BBC Master 128	01-ANB15-00432177

Overview

• Manufacturer: Acorn Computers.
• Production Years: The BBC Master 128 was introduced in early 1986 and remained in production until 1994.
• Historical Significance: The BBC Master 128 was the successor to the BBC Micro Model B, offering improved memory, processing power, and expandability. It was widely used in educational institutions and professional environments, continuing Acorn's legacy of robust and versatile computing solutions.
• Architecture: The Master 128 featured the MOS Technology 65SC12 processor, which was faster and more power-efficient than its predecessor. It also introduced advanced memory paging mechanisms to support larger applications and higher-quality graphics.

Specification

• Processor: MOS Technology 65SC12 running at 2 MHz.
• Memory: 128KB RAM, with options to expand up to 512KB using sideways RAM modules.
• Storage: Supported cassette tapes, floppy disks, and hard drives via expansion modules.
• Graphics: Motorola 6845 video controller, capable of high-resolution display modes and Teletext output.
• Audio: Texas Instruments SN76489 sound chip, providing three tone channels and one noise channel.
• Connectivity:
  • RS-423 serial port.
  • Parallel printer port.
  • Econet networking interface (optional).
  • Expansion ports for additional peripherals.
• Expansion: Supported second processors, including Intel 80186 and 65C102, for enhanced performance and compatibility with CP/M and DOS Plus operating systems.
• Operating Systems: Acorn MOS, with optional support for CP/M and DOS Plus via second processors.
• Common Faults:
  • Failure of the CMOS battery, leading to loss of configuration settings.
  • Age-related wear on floppy drives, causing read/write errors.
  • Leaking capacitors in the PSU, which can result in system instability or failure.
  • Overheating issues in systems with multiple expansions installed.

---

How Did I Acquire It?

Where Did I Get It From?

I purchased this on Ebay where it was marked as for spares or repairs

From the title it appeared to be a BBC Micro and was priced high for a BBC Micro so did not attract much interest,  however when you looked deeper at the photos you could see it was a BBC Master.
A cheeky low punt bid later and it's mine.

How Was It Described to Me?

BBC Computer Spares Or Repairs

Condition: For parts or not working

• bbc computer keyboard not sure of the current condition this has been stored for about 30 years, selling as parts to be fixed or as spares
• due to unknown condition 

Supplier Photos

Supplier Photos

---

Now That I Have It in My Hands

Initial Observations

The photos show the machine quite well, there is however so slight cracking of the plastics due to age along the join of the top and bottom.

Initial Inspection

There is a sticker saying that the battery has been switched over to a rechargeable one, however we do not know when and how it was setup so considering that and the known PSU capacitor issue the first steps speak to themselves.

Inspection Photos

Inspection Photos

---

Next Steps

Repair and Restoration Plan

• Replace the PSU and then recap the original
• I'm going to try the new USB PSU converters on this box
• Replace the battery with a known good
• Clean
• Test.

Goals

• Once this is up and running I think I would like to sort this out with  MMFS and install a memory card reader/
• Try out the Second processor options that are now offered via the raspberry Pi
• Get Econet up and running both locally and into the internet
• Maybe als see if I can link FujiNet into the network somehow.
• And as usual try and complete the setup with the full set of manuals, software,cables & boxes.

Challenges

• Once again finding original boxes and pollys to store these in is always a challenge

Wishlist

1. Original BBC Second processor units (6502 or z80)

 As usual I'll create new blog entries for every stage of the process