Tag Archives: bbc-acorn

Machine code Monitor in ROM on real BBC Acorn Hardware

My BBC Acorn model B is working again. The original monitor is still dead.

Time to play with some machine code and ROMs.

My machine has a NFS rom installed. (NetFS)

Econet was Acorn Computers’s low-cost local area network system, intended for use by schools and small businesses. It was widely used in those areas, and was supported by a large number of different computer and server systems produced both by Acorn and by other companies.

I found a ROM online called Gremlin. It is a 16K rom file. But at the moment I only got some 28C64 (8k) or 28C256 (32k) eeproms.

32k it is. But de beeb having address line A14 floating high, I need to flash the upper 16k of the 32k ROM.

So I made the 16K rom into a 32K using cat

cp Gremlin\ v1.21\ \(1983\)\(Computer\ Concepts\).rom 16k.rom
cat Gremlin\ v1.21\ \(1983\)\(Computer\ Concepts\).rom >> 16k.rom

minipro -w 16k.rom -p AT28C256

I got the rom from this page:

Below booting straight into the monitor program.