Re: Fun with 6530s and 6532s

From: MikeS <>
Date: Tue, 19 Jun 2012 22:12:50 -0400
Message-ID: <4A29AE5072684CE1AFD417C56230A97A@vl420mt>

Is the schematic for that 6532>6530 adapter of yours available anywhere?



----- Original Message ----- 
From: "Wolfgang Moser" <>
To: <>
Sent: Tuesday, June 19, 2012 6:08 PM
Subject: Re: Fun with 6530s and 6532s

> Hi Gordon,
> gsteemso schrieb:
>> Hi all,
>> The current thread that discovered 6532s where 6523s had been expected
>> reminded me of a project I was going to undertake... until I heard that
>> someone was theoretically already doing it, anyway. I have a 2040 PET
>> disk
> of course and theoretically I should have posted some progress report on
> it, if you were talking about my post from August last year:
> resp.:
>> drive (actually for practical purposes a 4040, as some prior owner
>> upgraded the ROMs to DOS 2.0) with a defunct 6530 RRIOT. In theory, a
>> 6532
>> RIOT and a small PROM can be combined on a little adapter board to
>> replace
>> a RRIOT, and in fact some later Commodore products apparently contained
>> such an adapter board right from the factory.
> As Ruud Baltissen found in an attempt to reconstruct a KIM-1 and as I
> can confirm, it is possible to "emulate" a 6530, if you know exactly
> about the ROM contents and the PLA fuse matrix. In contrast to Ruud's
> design I believe that I found a way to also reduce the 6532's feature
> set to the one of the 6530 (don't allow IRQ generation via PA7).
> To make a long story short what happened meanwhile:
>  * Nicolas Welte was in the need to let produce some prototype PCBs,
>    he was so kind to ask me on adding some of my 6530-to-6532 adapters
>    and I received 3 prototype PCBs of my design
>  * The first assembled board worked as expected and the same way as
>    the wired raster PCB prototype which I had to debug for months
>  * I had to relocate and all my projects were frozen for a while
>  * Around Easter this year I was happy to find another NOS part seller
>    who claimed to be able to obtain some 6530 chips with a CBM part
>    number known for the 4040 or 8050 drive. Most other NOS sellers
>    that I tried before weren't able to actually to deliver, but this
>    one did.
> Martin Hoffmann-Vetter and I found out that at least one of the IC I
> got, is a CBM part number whose ROM contents are not listed at
> Funet/Zimmers yet nor elsewhere in the Internet. With some tricks and
> the help of a slightly patched 6530-to-6532 adapter we managed to read
> out the ROM contents of both chips. Still these read outs need to be
> verified against a second pair of chips -- I ordered two chips from each
> available CBM part number.
>> As I mentioned above, I understand someone has a project going to design
>> such an adapter and make them available. In thinking about what such a
>> thing would entail, it occurred to me that it should be possible to do
>> the
>> entire work of a RRIOT with a relatively cheap modern FPGA, including the
>> ROM function. That's significant because just a 6532 by itself is usually
>> $10 or more before shipping.
> So what's the good news on my NOS seller findings from above? These
> chips did cost 10,- EUR each. In contrast to my solution where you need
> to get an adapter board PCB, a TTL IC and a 6532 IC (currently sold by
> Honkong/China part suppliers for less than 5,- EUR when ordering in
> quantities), a 6530 with a CBM part number belonging to one of the CBM
> IEEE floppy drives has the big advantage that you can at least repair
> SFD-1001 and 8250LP drives very easily. These drives come already with
> an adapter so that the ROM contents of the 6530 is replaced by the
> contents within the EPROM. To repair such a drive with a defective 6530
> all you need to get is a working 6530 from _any_ of Commodores IEEE
> floppy disk drive.
> If you need to repair any other CBM IEEE drive other than a SFD-1001 or
> 8250LP you have three options:
>   * Build a 6530-to-6532 adapter which is still not available from me
>   * Have some luck to find a parts supplier that sells exactly the CBM
>     part number that matches your drive type and mechanism and the CBM
>     DOS version as well
>   * Rip of the adapter board of a SFD-1001 or 8250LPT drive or perhaps
>     get a spare adapter board from somewhere else, replace the EPROM
>     with one that has the ROM contents burned in that exactly matches
>     your drive type, mechanism and DOS version, get a working 6530
>     with a CBM part number for any of CBM's IEEE floppy drive and
>     voila the result would be a perfect 6530 replacement
> This works because to my knowledge all CBM IEEE floppy disk drive 6530
> ICs have the very same PLA "fuse map programmed" (actually it is a mask
> programmed PLA, not based on fuses). The only difference is the mask
> programmed ROM contents of these ICs.
>> Such a device as I propose would fit on a really tiny board that would be
>> no larger than the original 6530 being replaced. Does anyone have enough
>> knowledge of such devices to say whether I've had a good idea here or an,
>> um, very much not so good one?
> On the long run, refactoring all these old chips into a hardware
> description language is necessary.
> But for the moment I see lots of sources for the 6532 IC, either chip
> pulls from old 6502 equipment other than CBM devices (my first Hongkong
> order for 6532 ICs were such chip pulls) or meanwhile China suppliers
> with factory new old stock ICs from Rockwell and others.
> And if this wouldn't be enough to refrain from starting work on a FPGA
> based replacement, there seem to be some 6530 left over in 35 year old
> stocks that wait for any buyers. Of course it's of course difficult to
> find 6530 CBM part numbers that match most up to date DOS ROM version,
> you always need to adapt the ROM contents onto an external EPROM, but
> that's it.
> Later this year I will try to write up more of the details about the
> findings from Martin and me regarding the ROM contents of the analysed
> chips and I also hope to find a way on how to provide some of you with
> either adapter PCBs or kits. At least for the European area since I
> believe Jim Brain would be happy to provide something similar for the
> North American market.
> Womo
> -- 
>  ------ to obtain more infos about me, look up the page ------
>    ------ | wm (at) wmsr (dot) de  ------
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Received on 2012-06-20 04:00:10

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