Re: [N8VEM: 13997] 68030 SBC project ideas

["J. Alexander Jacocks" <jjac...@mac.com>]

Andrew,

The 68040 is available in trays of 50 for $200, at Mouser.  That's
definitely reasonable, IMO.

- Alex

On Sun, Jun 24, 2012 at 7:43 PM, Andrew Lynch <LYN...@yahoo.com> wrote:
> Hi!  Good point Alan.  There is no way I am going to be assembling all of
> the PCBs.  Let’s see what our options are.
>
>
>
> I am thinking even the MC68040 CPU itself may make this project impractical
> though.  Check out the prices for MC68040 on findchips.com!  Whoa!  $200+
> per chip.  Even on Ebay these chips are >$45 each!  Oddly even the QFP
> packages are about the same price as the PGAs – expensive!
>
>
>
> Thanks and have a nice day!
>
> Andrew Lynch
>
>
>
> From: n8...@googlegroups.com [mailto:n8...@googlegroups.com] On Behalf Of
> Alan Hightower
> Sent: Sunday, June 24, 2012 6:30 PM
> To: n8...@googlegroups.com
> Cc: <n8...@googlegroups.com>
> Subject: Re: [N8VEM: 13992] 68030 SBC project ideas
>
>
>
>
>
> The best bet would be assembled boards from China.  While building up boards
> for folks sounds like a nice goodwill job, trust me, the 3rd, 4th, 5th, 8th,
> 10th batches are no picnic.  I'm researching a few places now.  Even though
> SMT is a lot quicker to build up w/ stenciling.
>
>
>
> A good design localizing all SMT on a module PCB should come first though.
>
>
> Sent from my iPad
>
>
> On Jun 24, 2012, at 5:55 PM, "Andrew Lynch" <LYN...@YAHOO.COM> wrote:
>
> Hi Dave,
>
> Yes, there are MC68040 in PGA-179 (PTH) packages available according to
> findchips.com and ebay.  However the price differential on the MC68360, if
> we choose to go that way, pretty much would force at least one large SMT
> component.
>
>
>
> Which brings us to the question of pre-assembled or partially assembled
> boards.  Ugh.
>
>
>
> Does anyone have an SMT toaster oven and is willing to partially assemble
> some PCBs?
>
>
>
> Thanks and have a nice day!
>
> Andrew Lynch
>
>
>
> From: n8...@googlegroups.com [mailto:n8...@googlegroups.com] On Behalf Of
> yoda
> Sent: Sunday, June 24, 2012 3:33 PM
> To: n8...@googlegroups.com
> Subject: Re: [N8VEM: 13982] 68030 SBC project ideas
>
>
>
> Hi Andrew
>
>
>
> Have you been able to find any 68030s or 40s that are not SMT or worse BGA?
>   I have been looking around and they don't seem to exist - that will mean
> some SMT on the board - maybe we make a small board for the processor /
> memory and cpld/fpga to plug it back onto a board for other I/O ?
>
>
>
> Dave
>
> On Sunday, June 24, 2012 9:37:25 AM UTC-5, lynchaj wrote:
>
> Hi Dave!  Thanks!  Agree 100% lets discuss some design concepts and see what
> sorts out.  Given the scope of this project we need to think this through
> before launching and really examine the assumptions.
>
>
>
> Yes, there are many Intel/Zilog designs already and I agree the 68K
> architecture ISA is much nicer and cleaner than the x86.  I especially like
> the 68040 since it has the MMU and FPU built in.  However I am trying to
> keep an open mind on the 68K vs x86 because there may be some major hardware
> advantages to the x86 side (386EX for example).  In either case the key will
> be interfacing the RAM SIMM, boot ROM, and IO Propellers.
>
>
>
> Agree the Propellers won’t be able to keep up with the CPU clock speed
> assuming it is 16-20 MHz.  However I am thinking we can decouple the
> Propeller cogs from the CPU bus by latching the pins.  Something like a pair
> of 74LS373s to latch the CPU data bus pins to and from the IO data bus and
> another 74LS373 to latch the control pins  (CS, PropReady, etc) between the
> two.  Then the CPU can poll the IO latches rather than the Propellers
> themselves.  This *should* simplify the PASM required as well since it would
> reduce the timing dependencies.
>
>
>
> I am not fixated on the Propellers either but they are the most capable
> hobbyist friendly IO controllers I am aware of.  Where else can you get a
> VGA display, PS/2 keyboard, and microSD in one 40 pin DIP plus a few
> passives?   That’s enormous density and seems like a natural fit to me.
> They are not perfect though as they only really are VGA text capable.
>
>
>
> Due to the complexity of the bus interface logic and sheer quantity of data
> and address pins the use of programmable logic devices may be unavoidable
> with a 68040 CPU especially if we want to keep the PCB affordable so I can
> see where this is headed – either FPGA or CPLD for the glue logic.  That’s a
> bit of disappointment but we may yet be able to use PTH components so at
> least we avoid SMT and its issues.
>
>
>
> There are still a selection of CPLDs in the PLCC 84 format.  It may require
> two chips for all the pins though with some sort of split between the pins
> like IO vs memory busses.  The 68040, the RAM SIMM, and the boot ROM are
> already PTH components.
>
>
>
> http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1724211_-1
>
>
>
> Jameco part number 1724211 (not cheap but we may be able to do better)
>
>
>
> Thanks and have a nice day!
>
> Andrew Lynch
>
>
>
> From: n8...@googlegroups.com [mailto:n8...@googlegroups.com] On Behalf Of
> yoda
> Sent: Saturday, June 23, 2012 3:53 PM
> To: n8...@googlegroups.com
> Subject: Re: [N8VEM: 13962] 68030 SBC project ideas
>
>
>
> Hi Andrew
>
>
>
> Hi I would be very interested in helping on this as I am pretty familiar
> with 68K now and of course the propeller as well.  I think the propeller
> would is going to be a challenge especially at higher frequencies.   The
> Lava board has gotten me interested in other approaches as well.  The I/O on
> the propeller is pretty limiting at the moment - the prop II whenever it
> becomes available would be a better fit.  Believe it or not (I know it is
> sacreligious) I have started play with the Xilinx Spartan FPGA that is used
> on the Lava board - I think there is promise for something like that - maybe
> we can have a breakout board that would plug in that has it mounted (as I
> know a lot of builders don't want to get into SMT technology - I am started
> to get the hang of it).
>
>
>
> I think we have enough Intel boards in the world and I really like the 68xxx
> programming model much better than Intel.  We should start throwing some
> design ideas around and see what we can come up - I am happing to do some
> bread boarding where possible.
>
>
>
> Dave
>
>
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