BBC Microcomputer Model B+ 128K

[BBC Micro]       [Computers ]

Introduction

The BBC Model B+ 128K was the final BBC model, it squeezed every last bit of memory out of the 8-bit computer. It is the same as the BBC Model B+ 64K with the addition of a further 64K RAM which is used as sideways RAM and can have ROM images loaded into it. Compared to the BBC Model B, it has:

• a redesigned motherboard with the ROM sockets moved to the lefthad side of the board so that they are not covered by the keyboard.
• the CPU is changed from a 6502 to a 65C12
• a new OS version 2.00 to support the new features. The startup messages is changed from "BBC Computer" to "Acorn OS"
• a Western Digital 1770 disc controller, instead of the Intel 8271, which supports ADFS as well as DFS
• a new DFS version 2.10 to support the WD1770
• additional 32K RAM with 20K for shadow video memory and 12K workspace
• additional 2 ROM expansion sockets

It was launched in 1984 shortly after the BBC Model B+ 64K and was soon replaced by the BBC Master.

Manuals and documents

See BBC Micro .

In November 1985 Acorn User published a News item titled "Enter ther 128k Beeb".
In December 1985 Practical Computing magazine published a review titled "BBC Plug-ins "

 BBC Model B+128K 

I bought this example on ebay in October 2002. It is in near mint condition, still having the plastic film on the keystrip. Here are some pictures:

BBC Model B +128K box

BBC Model+128K in polys.

Note the distinguishing 128K labels on the back left, on the keystrip and at the right front.

BBC Model +128k with the top off.

You can just see the additional RAM on a vertical board on the right of the picture.

BBC Model +128K motherboard

The BBC Model B+ 128K has a vertical 64K RAM card on the extreme right. This additional 64K is used as sideways RAM and can have ROM images loaded into it.

Specification: