Examples of Memory MAP with 2x Clonix-D?

[Diego Diaz]

Hi all,

On a previous mail with the OP I noted that: "The only safe configuration for two of my modules plugged simultaneously is 2x Clonix-D (or NoV-64d configured like Clonix-D)".

The key word here is "safe".

While running NoV-64d (HEPAX emulation) along with Clonix-D is 'possible' and will not cause any address or bus conflicts; it will stress the power supply IC beyond its
standard functional limits for "continuous"(*) use.

Even though this part is a bipolar IC and can take a bit of 'abuse' quite well, this may cause premature failure in the long term, hence this configuration should be avoided
as a working environment. It may work for years, but I won't risk an unobtainable IC betting against that odds.

In all my functional scenarios there is only one case where it is used and just for a brief period of time (meaning a few seconds) when loading/saving a ROM image to/from
a PC file thru the USB-41 interface module. The USB-41 is basically a Clonix-D with a dedicated area (both hardware and software) to interface with the RS232/USB adapter.

(*) The Power supply IC, is a bipolar step-up DC-DC converter. It is nominally rated for 20mA continuous current (1826-0566). It was (and still is) a common practise to rate parts' safe operation about 130% below their "Absolute maximum ratings". Also the IC description states that the limiting resistor (R2) can be modified to allow higher current drains.

In the later models this IC is replaced with 1826-0953 and R2 is suppressed allowing a free run to max current when needed.

In a bipolar device the usual "killer" is the current-time>temperature increase (given no overvoltage is applied; which won't be the case here).

So, short periods of time running up to 10 times the continuous rating are still in the "safe" area.

In the HP-41 the power supply IC is 'resting' most of the time, since it is not used while the calc is in light or deep sleep mode.

I ran several bench tests while checking the NoV's modules design on both -0566 and -0953 IC's, draining up to 100mA for 24hr confirming that the parts suffered no damage and my 41CX (which I used for the -0953 test) is still healthy after more than 15years of abuse.

Using two Clonix-D simultaneously is well below the functional continuous limit of the power supply IC's.

NoV-64d, can rise to 50mA max. which is still ok for continuous use and have proven safe since no HP-41 damage has been reported after 19 years of use of hundred of modules in the field.

I would like to keep this safety record unchanged, hence I won't recommend to plug two of my modules when configured as NoV-64d.

Sorry if this post has turned out to be too long and techie.

Hope this clarifies the point.

Best wishes.

Diego.