25 Oct
2005
25 Oct
'05
4:07 p.m.
On Tue, 25 Oct 2005 21:21:09 +0100 (BST)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:
That leads into what I was going to make as a comment. Keep the system pluggable
and modular, and put several controllers on board to cover multiple needs. Facing the
micro, it's just several I/O ports per controller.
--
http://sasteven.multics.org/MacSE30/MacSE30.html
OK, I'm wanting to build a board with an 8 bit CPU (probably Z80,
possibly 6502) and a floppy controller IC on board with the intention of
hanging it off my PC (via serial or parallel, undecided yet) and
allowing me to read and write *most* formats from various 1980's 8 bit
micros...
Intel's 8271 looks like a possibility at the moment, but I thought I'd
I would avoid the 8271, if only becuase it's somewhat rare (the BBC micro
being the only common machine to use it). And there's the thing that I've
never seen an Intel LSI chip without a design misfeature ;-)
I'd go for one of the Western Digital ones. If you're lucky you'll find a
2793 or 2797 or something like that. Everything, including the data
seperator, is on-chip. Setting up is easy.
The 1770 (or 1772) or the 1773 aee other easy-to-use chips.
Be warned that the 1771 is a bit odd. It's FM only _and_ it can write a
Data Marker than no other normal floppy controllers can. The problem is
that that data marker was used on the TRS-80 Model 1 (on the directory
cylinder only). If you want to copy disks from that machine, you need the
1771 (to the extent that the double-density upgrades for the Model 1
added a 1791 or similar, and kept the 1771 alongside it).