Re: Copying ROMS ?

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Motorola MCM68369/68370 has four select lines - Pins 20, 22, 26, & 27 are
all factory set (H/L) chip selects on this Mask ROM (8192 X 8).

John:-#)#

At 08:12 AM 22/06/2002 -0700, Mike Davis wrote:

>Like I said below:
>EPSON BASIC1R0 M64020AA
>EPSON BASIC1R0 M64021AA
>EPSON BASIC1R0 M64022AA
>EPSON BASIC1R0 M64023AA
>
>The other writing is simply date code information.
>
>The thing is, like I have said, I have a 2nd HX-20 that has 27C64s
>installed. So, I was going to copy the BASIC to 27c64s and use in
>the 2nd unit to have a BASIC machine.
>
>Someone suggested that the masked ROMs might have some sort of
>special non-standard select method within the ROMs. But if that was
>the case, the 27C64 wouldn't work, unless there was some difference
>in the board (No PALs on this board). I'm going to disassemble it
>today and see if the 2nd unit has some rewired ROMs.
>
>But, I have a 2nd problem that I'm trying to work off of this board.
>I pulled the BASIC ROMs from the 1st unit and performed a hard reset,
>clearing RAM. Still ran BASIC and the monitor program that were
>supposed to be in ROM (ROMs were completely out of the system).
>
>I was going to simply sway ROMS and see if they worked in the other
>system but for some reason, the systems behave the same, regardless
>of which set of ROMs is in either machine.
>
>I thought perhaps the program is loaded into resident memory but the
>manuals don't mention this and I don't know how to force a reload. I
>know their other machine, PX-8, behaved this way.
>
>
> > Is there any common numbering on the masked parts that might give a
> > clue as to what they REALLY are?
> >
> >
> > Mike Davis wrote:
> > >
> > > That was the first thing I tried. It read in all blank. That is
> > > the problem that I'm trying to resolve.
> > >
> > > > If 2764s are known to work just read the ROMs as 2764s.
> > > >
> > > >
> > > > Mike Davis wrote:
> > > > >
> > > > > I have verified that I can read and write other 27c64s and I
> > > > > also tried swapping ROMS however there is another small glitch.
> > > > >
> > > > > Apparently the HX-20 runs the programs out of RAM. I guess it
> > > > > loads from PROM and runs from RAM. I removed all of the BASIC
> > > > > ROMs and performed a hard reset and when it comes back, it's
> > > > > still running BASIC, without the BASIC ROMs even installed.
> > > > > Wierd!
> > > > >
> > > > > I have looked through the manuals to try and find a way to force
> > > > > a reload but no go (so far). I might try removing the internal
> > > > > batteries and see what happens.
> > > > >
> > > > > The manual also mentions that one can use 27C64s in the HX-20.
> > > > > There may also be one other thing that is causing the problem.
> > > > > I am trying to read the ROMS using family/pin codes for other
> > > > > ROMS. I don't find that part number and have tried a number of
> > > > > other 8K ROM fam/pin codes and none give me anything but blank
> > > > > loads.
> > > > >
> > > > > Perhaps that is part of the problem?
> > > > >
> > > > > Mike
> > > > >
> > > > > >
> > > > > > Verify that you can read another 2764 (incase you have reader
> > > > > > problems).
> > > > > >
> > > > > > Can you swap the 2764 for the Masked ROMs & work without
> > > > > > changing jumpers/settings/wiring?
> > > > > >
> > > > > > I see there are a few HX-20 collectors on the net, they may be
> > > > > > more informed.
> > > > > >
> > > > > > Kev
> > > > > >
> > > > > > >
> > > > > > > I think I understand what you are saying. I'm sure they are
> > > > > > > Masked ROMS or at least that would make sense. They are a 4
> > > > > > > chip chipset with numbers: EPSON BASIC1R0 M64020AA to
> > > > > > > M65023AA.
> > > > > > >
> > > > > > > The thing is however, that in identical machines, the other
> > > > > > > EPROMS are 27C64 so the pinout would seem to have to be the
> > > > > > > same or the EPROMS would not work right in the other
> > > > > > > identical machines, would they?
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > >
> > > >
> >
> >

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Received on Sat Jun 22 10:41:44 2002