years (many) I built a xz80 machine around the Z80/dart/CTC/eprom and ram
and as a change up for early 80s 1982 end of year to be precise...?
BM? bubble memory actually magnetic bubble memory.? I was lucky
enough to get two BPK7720 bubble memory boards each doing 128Kbyes.
Cost was about the same as a 5.25" floppy drive.? ?The Intel part with
supporting ICs was 1980s tech not in existance in the 70s.? TI had the
magnetics part earlier but the supporting ICs so it took a lot to make
their part work and it first appear as local memory in the Silent 700
series as?replacement for ASR33 TTY.? The later 745 had a
bubble memory for local storage for later transmission.
What brought that to mind is Scott Bakers revisit...
I still have the system I built up, and its operational.? All three boards
two BMC (256KB storage) and Z80SBC.? The downside for BM system
was high power drain when active and it wasn't very fast compared to
an average floppy.? It did run CP/M-V2.2.? IT highlighted the problem
of CP/M, floppy sized disks are too small.? To save as much of the
BM for storage the whole monitor, OS, and Bios was loaded into
the first 16K (27128) part available then rather than loaded from disk.
Building physically small systems that are high performing at the
single board level has been a long time thing.? The things that made
Z80MC and similar possible was larger rams?(32k bytes and larger),
large Eproms, and enough integration of IO (Z80 dart/SIO) to cut
the parts count to very few mostly glue parts.
The addition of uSD makes for smaller but lots of storage, CMOS?
parts like Z80, SIO, and other parts in the early 80s made
battery power a practical enterprise.
Allsion
