Re: CBM-II Character Set and Colour Expansion

Den Tue, 17 Jul 2018 09:18:06 +0200 skrev Francesco Messineo
<francesco.messineo@gmail.com>:
> On Tue, Jul 17, 2018 at 1:35 AM, Mia Magnusson <mia@plea.se> wrote:
> > Den Mon, 16 Jul 2018 22:31:10 +0200 skrev Francesco Messineo
> > <francesco.messineo@gmail.com>:
> >> On Mon, Jul 16, 2018 at 9:54 PM, Mia Magnusson <mia@plea.se> wrote:
> >>
> >> >
> >> > A plus with using an extra eprom is that the eprom would be the
> >> > same kind that is already needed so there is no risk that anyone
> >> > building this thing will be hindered by lack of tools to
> >> > program  a 16V8. (But yes, almost all eprom programmers probably
> >> > can program a 16V8 too, but still).
> >>
> >> Well, no, not the most vintage ones at least. I have several
> >> E(E)PROM programmers
> >> (Data I/O, Digelec, Hi-Lo) and none can program PALs. Some can
> >> program microcontrollers, with or without adapters.
> >> Yeah, I know, I still use '70s and '80s stuff and I can only blame
> >> myself for that :)
> >
> > But then they are really old? I'm not sure but would gess that my
> > All-03 and my Data-I/O Unisite would program the PAL's.
> >
> 
> Yes, the Unisite and the All-03 will probably program PALs, but these
> are quite new programmers
> compared to what I have :)
> The problem is that PAL programming algorithm were never made public,
> so in the low cost programmers
> they would almost never be included.
> PAL manufacturers wouldn't like to be blamed for a marginal programmed
> device or a device that would fail
> too early, so they licensed the programming algorithms to well known
> manufacturers and at a high cost too I believe.
> Many people don/t realize how the correct algorithm matters even for
> programming a simple EPROM.
> Some months ago I helped a guy troubleshooting his fat40 PET and he
> was programming 2532 and 2532A EPROMs
> with a brand new chinese USB programmer (probably the most famous
> current programmer on ebay).
> It couldn't program 2532A at all (it's just a reduced VPP 2532) and
> the 2532 (non-A) were programmed so badly
> that the  PET was not even successfully booting most  of the times.
> After he was trying to desolder every other IC on that poor PET, I
> decided to send him a complete set of programmed
> EPROMs for that board (using my DATA I/O) and they worked fine.
> He sent me some of the EPROM he had programmed and they didn't even
> verify correctly.
> Yes, it could have been his particular unit that was DOA, ot who
> knows. And yes, keeping a vintage programmer healthy requires some
> efforts sometimes. YMMV
> Frank
> 

Interesting!

I've had trouble programming ordinary 2732's with my Hi-Lo ALL-03. Had
to restart the programming a bunch of times, each 256 byte block (or
whatever size the programmer use) would fail one or more times and
after some retries it would read back correct and the programmer would
go on to the next block and the procedure would repeat.

I'm not really sure what causes this, I haven't really investigated. It
doesn't look like there are loads of bad capacitors in the programmer,
which could otherwise explain it.

Btw I remember a friend had a programmer called "SmallProg" for Amiga.
It would program most cmos eprom fine, but when we tried programming
old 2764's it would just fail. We ended up soldering a wire onto the
point between it's 21V generator and the transistor that switches VPP,
and hooking up a small 12V lead acid battery in series with +12V from
the Amiga to provide about 24V DC directly to the programmer, then it
did burn the 2764's fine.

I assume it would had worked changing the (proprietary) software to
program the eprom far slower, i.e. a short puls and then let the charge
pump recover from the load, instead of trying to program as fast as the
eproms are specified to be programmed.

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