Slowing down a GX?
jo...@cnct.com
While I would love to be able to speed up my stock GX, I know that
wouldn't be easy. What I'm looking for now is a way to easily slow down
the GX so it can run some older libraries at a more convenient speed.
Specifically, I'd like to be able to run micro.lib and embryonx.lib, but
for the most part they zoom by.
Jose
Dave Arnett
Replying by e-mail and by post to comp.sys.hp48:
jo...@cnct.com wrote:
For a variety of reasons, I built access to this capability into the
circuit board. To make this happen, you have to open the HP48, which
I do not recommend, and alter some solder jumpers. This voids your
warranty and may have bad cosmetic impacts as well. Most folks ignore
me when I talk about that. So for those of you who have already broken
into the inner sanctum of HP48 hardware, here's the story.
Look at the HP48 G/GX circuit board. Point the incredibly powerful
infrared devices away from yourself. The big square chip near the
IR and serial spigots is the Head Hombre Circuit Chip Itself: YORKE.
Near the top left corner, at the base of the serial connector which
you'd never confuse with a phone jack, is a pattern that looks like
two interlocking J's. That's a solder jumper site, lovingly named
by myself as X1.
Now let your adoring gaze move downward along the board. Below the big
ICs are three twist tabs used to hold the display in solid contact with
the circuit board. Near the center tab is another interlocking J pattern.
That's X2. (My kids got all the good names.)
X1 and X2 provide a simple means of connecting Yorke pin 37 to Vdd or to
Ground. You should find X2 has a blob of solder on it, tying pin 37
to Vdd. This makes Yorke run at double speed. If you remove that glob
and instead bridge X1, pin 37 will be grounded and the Yorke will run
at single speed, just like the 48S and SX.
A hint to the technically challenged: Bridging BOTH X1 and X2 creates a
power-to-ground short. Most engineering schools recommend not doing
this, but what do they know?? Enough.
Those of you who would like to change speeds daily can design and install
an electrical gearshift of your own preference. There is not a pair of
test points for you to use as solder pads - sorry! If you use the through
hole via up near Yorke, remember not to poke too much wire through the
hole as you will likely short to something on the other side. And if
you have a GX, be sure that you route your wire(s) so it/they won't
interfere with card insertion.
Good Day!
Dave.
------
I don't speak for HP when I post here.
And I really don't advocate opening up the HP48.
jo...@cnct.com
I've saved this message for when I get enough guts to actually try
opening my GX and take a soldering pencil to it. While a switch would
make things _SO_ much easier, I know better than to try this myself.
Is there any way of doing simulating the slowdown through software, maybe
a program running a delay loop and calling a program or lib from within?
Jose
-Will try to open his GX sometime after a labotomy.
_DEiCiDE_
jo...@cnct.com wrote in article
<Pine.SUN.3.91.961010...@cnct.com>...
>
>
> > >While I would love to be able to speed up my stock GX, I know that
> > >wouldn't be easy. What I'm looking for now is a way to easily slow
down
> > >the GX so it can run some older libraries at a more convenient speed.
> > >Specifically, I'd like to be able to run micro.lib and embryonx.lib,
but
> > >for the most part they zoom by.
> >
> > And I really don't advocate opening up the HP48.
>
>
I opened my HP48G and it was pretty easy...i'm gonna add more ram pretty
soon....i'll try just about anything on mine...so lemme know what u want me
to try..:)
I interfaced a pic chip to the serial port...so now i can send and receive
messages from the chip...and also send commands..:)
Walter R Francis
On 10-Oct-96 17:04:06, jose <jo...@cnct.com> wrote:
>I've saved this message for when I get enough guts to actually try
>opening my GX and take a soldering pencil to it. While a switch would
>make things _SO_ much easier, I know better than to try this myself.
> Jose
> -Will try to open his GX sometime after a labotomy.
I suggest getting one as soon as possible if you took Dave's message
seriously.
--
-.-. --.- -.-. --.- -.-. --.- -.-. --.- -.-. --.- -.-. --.- -.-. --.- -.. .
. Walter Francis _. KT4LH .
- HP48GX Alinco DJ580 Icom 281 Kenwood 530S o:o -
. Wa...@POP.UKY.EDU Life begins on 80 .
--... ...-- --... ...-- --... ...-- --... ...-- --... ...-- --... ...-- ..
Dave Arnett
Replying by e-mail and by post to comp.sys.hp48:
wa...@pop.uky.edu (Walter R Francis) wrote:
>
>On 10-Oct-96 17:04:06, jose <jo...@cnct.com> wrote:
>
>>I've saved this message for when I get enough guts to actually try
>>opening my GX and take a soldering pencil to it. While a switch would
>>make things _SO_ much easier, I know better than to try this myself.
>
>> Jose
>> -Will try to open his GX sometime after a labotomy.
>
>I suggest getting one as soon as possible if you took Dave's message
>seriously.
>
Hi, Wally.
I try not to establish too serious a tone, but the gist of my post was
factual. I did put the jumpers on the board for this very reason. There
are other jumpers on the board, as well. Why did I do it?
1. We were not certain whether there would be a demand for the 48SX after
the G and GX were introducd. I have jumpers on the board which would
allow you to build an HP48SX on this circuit board. That task requires
rerouting the card detect and select lines and (optionally) running the
CPU at 1X speed rather than 2X speed.
2. There were problems with the yield of Yorke ICs from NEC which would
run at 2X speed at all temperatures. We had a contingency plan that would
have made all HP48G units run at 1X speed until the problem was resolved.
The jumpers allowed us this option, had it been necessary. Thankfully,
the yield improved and we didn't have to exercice the option.
3. The old RAMBOX development systems used by the software team would
only support 1X operation. The ability to select 1X speed when runnig
code from the RAMBOXes, and then switch to 2X speed when running from the
EPROM was a design requirement. I saw no reason to delete this feature on
the production board. My EPROM unit and Charlie Patton's unit had a
gearshift for switching speed on the fly without a slodering iron.