Fwd: Re: Fwd: Re: 8250 LP Double disk drive for the

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Fri Jul 4 16:09:00 2003

> --- Tony Duell <ard_at_p850ug1.demon.co.uk> wrote:
> > > It suggests that the "fragile" part is a 6530 - a part made by
> > > Commodore that was always customized for its particular application...
> >
> > Mine has that, but I thought the chips on the daughtercard were a 6530
> > (from which the ROM section is not used, so any 6530 should work), and a
> > ROM. Oh, and maybe a bit of glue logic.
>
> Ah... they must have been recycling old 6530s rather than making
> new ones. That's handy to know (I have a few DOS 1 6530s from


Yes. I've looked at the schematics and 6530 data sheet, and it's certain
from the former that the chip is a 6530. The ROM is not used (RSO is tied
high). Instead, there's a 2716 EPROM, with a 74LS04 inverter to sort the
chip select out.

Looking at the data sheet, it appears that certain other things were
mask-selectable, not just the ROM code. Things like whether certain pins
were port lines or chip selects. So I guess not _all_ 6530s will work.
But I think all 6530s from CBM drives will.

-tony
Received on Fri Jul 04 2003 - 16:09:00 BST