From: Jack Rubin (jack.rubin_at_ameritech.net)
Date: 2007-12-13 14:17:06
Jim,
I guess I should be explicit rather than implicit - I'm in for two
boards with the intention of preparing a couple 8250 versions.
Jack
Solder Monkey
> -----Original Message-----
> From: owner-cbm-hackers@ling.gu.se
> [mailto:owner-cbm-hackers@ling.gu.se] On Behalf Of Jim Brain
> Sent: Thursday, December 13, 2007 1:35 AM
> To: cbm-hackers@ling.gu.se
> Subject: Re: 1541IDE and 1541IDE-S -- and 8250IDE? (and 64IDE, now)
>
>
> ruud.baltissen@abp.nl wrote:
> > Nope, A5 is just needed to read/write the High byte of the data ie.
> > D8..D15. Have a look at IC7A, the first half of a 139, you will see
> > that both A5 and R/W are responsible for selecting the
> 573's. In fact
> > only the addresses $20 and $30 are used, the rest are
> mirrors of those
> > two addresses.
> >
> I understand. And, I think your argument that placing the hi byte a
> ways off is very valid, as it takes the same amount of code
> to load 16
> byte values either way, but your approach saves a lot of time when
> loading a string of 8 bit values to registers. Thus, I'm convinced.
>
> But, as we discussed, I did change the IDE16 design slightly.
> Instead
> of putting the hi byte after both sets of IDE registers (IDE1 and the
> phantom IDE2), I modified the design so that IDE1 low registers are
> followed by the hi byte, mirrored, followed by the IDE2 addressing,
> followed by the hi byte again. For the others, I feel like this uses
> the memory map more sparingly, as a design could use 32 bytes for the
> IDE interface and then decode the next 32 bytes for something
> other than
> a secondary IDE interface.
>
> > If it was up to me, I would start in the same way as I did with the
> > 1541: soldering the interface and trying to make this work
> first only
> > using a BASIC program. My question: is it possible to force
> a program
> > up on the FDC of an IEEE drive ???? That I really would
> like to know!
> > The IEEE drives have a big advantage: a sepperate FDC. IMHO
> this means
> > we can adjust the ROM so the FDC is able to handle an
> harddisk without
> > having to alter the software for the other 6502. Remark:
> don't forget
> > that the ROM for this 6502 contains some routines meant for the FDC.
> >
> As noted earlier in PM, I think the 8250 folks should get this board,
> plug it in, and make a small perfboard to do the SELect.
>
> Here's what I did thus far:
>
> Merged your IDE8 and IDE16 schematics into 1 design. I used
> the address
> select and such from the 16 bit design (very clever, I must say), but
> used the '244 and NAND gates for the inverters, as I wanted
> to drop the
> '138 from the IDE16 design and found I could do so by doing:
>
> /(/(/SEL)*PHI2)
>
> This gives me an active low when SEL is low and PHI2 is high.
>
> By merging the designs, I was able to get to 6 ICs (ditched a
> 139), and
> had some room left over. So, with the extra room, I added a C64
> expansion port connector and wired lines up as appropriate.
>
> I can't take credit for the design, but I am happy with the
> merge. Out
> of the design, I got:
>
> * Ruud's 8 bit interface
> * Ruud's 16 bit interface
> * Poor man's IDE64 interface
>
> in 2.6x3.6" of board. 9 will fit on a panel, so I can spin 18 boards.
>
> I tried to hook up all the 6502 lines to the C64 connector,
> so someone
> could use it on the '41 as an expansion port or could wire an
> EPROM into
> it for 64 use, but ran out of room for traces and I didn't
> want to start
> going to more esoteric lengths to get all the lines to fit.
>
> I know a few volunteered to look at the design. I think this is the
> final one, and I put pics up at:
>
http://www.jbrain.com/vicug/gallery/1541ide
I'd appreciate some eagle eyes, comparing the board to Ruud's initial
designs. Let me know, and I can potentially spin the boards this week.
Oh, and Merry Christmas. Al Anger has offered $100 towards the cost of
the run. Thus, the first $100 of boards will be given away. To be
fair, probably 1 free board, and additional ones at cost. It looks like
5-5.50/board at the run rate I anticipate.
I have 6 boards spoken for thus far, not counting the 2 folks who wanted
more than 1 board. Any others?
Jim
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