Old programmers (was: CBM-II Character Set and Colour Expansion)

I didn't want to hijack the original thread, so subject edited...

On Tue, Jul 17, 2018 at 9:12 PM, Mia Magnusson <mia@plea.se> wrote:


>>
>
> 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.

A couple of suggestions:
1) Always try to match manufacturer and exact variant of the EPROM
when programming it,
    as it was common to change for example the Vpp or suggested
algorithm and just add an A/B/C letter after the part number (or even
worse, change the prefix).
2)  Always verify the programmer is working well wiith respect to
voltages and timings.
For example, my old Hi-Lo uses an ISA card and would never respect the
required timings if
installed on a 486 class machine (yes, it's old) with a regular DOS
installation.
I had to run it under linux/dosemu that allowed me to configure a
lower clock speed.
Where procedures and manuals were available (like on the Data I/O
units) I completed the test and calibration procedures making sure all
voltages are in spec. Of course I've also checked for bad capacitors
and other electronic faults when I acquired them.
Particularly bad is the Digelec 824 because no manual or schematic
could be found for it, so I can't find why it fails on some types and
works on others.

>
> 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.

as any other old electronic device, it must be kept in good shape :)

>
> 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.


oh my... :)
I started in the '80s with a locally made clone of the C64 based Promenade C1,
it worked (and still does) fine. What I liked about it, is the
complete configurability of voltages and algorithm, but you must read
the part datasheet before deciding what program options you should
use.
It never failed a programming (unless a part was bad).

> 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.t

most algorithms are interactive anyway.
Wrong Vpp (higher) is an EPROM instant killer (don't ask how I know it).

Frank