RE: 1541IDE and 1541IDE-S -- and 8250IDE? (and 64IDE, now)

From: Jack Rubin (
Date: 2007-12-13 14:17:06


I guess I should be explicit rather than implicit - I'm in for two
boards with the intention of preparing a couple 8250 versions.

Solder Monkey

> -----Original Message-----
> From: 
> [] On Behalf Of Jim Brain
> Sent: Thursday, December 13, 2007 1:35 AM
> To:
> Subject: Re: 1541IDE and 1541IDE-S -- and 8250IDE? (and 64IDE, now)
> 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:

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?


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