Tag Archives: PAL

Upgrading the NumberSmasher

After a long time, I had a look at my 3 NumberSmashers again. Looking closer, I spotted a difference.
One had a silkscreen print saying “V1.2” while the others were “V1.1”. So why not upgrading the NumberSmasher yourself?!

Step 1

The most obvious fix the V1.2 had was a 47ohm resistor fitted between one pin of the 40MHz oscillator and pin-1 of an IC called “A447-0050-10 “. That’s a “10 tap leading edge delay module” made by Bel Fuse Inc.. Pin 1 takes the input signal and each other pin  adds a delay of 5ns.
So I assume this fix was meant to reduce noise on the delay chip input to make its output cleaner.

Anyhoo, here’s the quick and easy howto. The below picture shows the section of a NumberCruncher V1.1. near the almighty i860. Next to it is the (now empty) socket for the 40MHz oscillator. Next to that you see the 10-pin delay chip which pin-1 already had been cut and slightly bent upwards.
We need a bit of pin-1s leg so when cutting it, be sure to cut it as close to the board as possible!

NS_premod.jpeg

Now for the next step. Get a 47ohm resistor and shorten its wires to bridge the space between the bent leg of the delay chip and the output pin of the oscillator (see below picture).

NS_860_postmod.jpeg

To make things perfectly clean, remove the pin remains by flipping the NS860 over and pull the remains with your solder iron and tweezers.

Step 2

I thought this would be a simple fix, too. There are some retrofitted jumper-wires on the back of the NumberSmasher near the ISA connectors.

NS860_patchwiresI’ve color adjusted the photo to make the wires more visible. Colored arrows show start and end of each wire

But taking a look at the chips those jumper-wires are connected, it showed that the two PAL22V10  of the V1.1 board were replaced by two PALCE610H – which is a completely different beast, same number of pins, everything else varies:

max in max out macrocells Specials
PAL22V10 22 20 10
PALCE610H 20 16 16  D, T, J-K or S-R Flip_Flops, counters and large state machines possible

Additionally here’s a side-by-side of the pinouts. This immediately explains the two long jump-wires from pin-1 to pin-13 (red & blue arrows) which connect the two clock inputs.

20v10_610h

Here’s the PALCE610 in place:

PALCE610It’s the one at the bottom in the middle (named U93) and one hidden beneath the link-interface board (U-88).

My assumption is, that the PALCE610 has a completely different programming and the jump-wires just support the changes made, i.e routing the outputs of pin3 to input pin2 (green) respectively pin4 to pin 2 (pink) .

Next up: I will get out my Über-Programmer and try reading it – but I have low hopes, as MicroWay normally set the protection fuse on all the GALs/PALs they used.

Update

Wow, that was unexpected. Both PALCE610 hadn’t had the protection fuse set – at least on my retro-fitted V1.1 board. So lo-and-behold, here are the JEDEC files for you to program your own PALCEs!  And because I couldn’t resist, I’ve disassembled the JEDs and added the PALASM code in the archive, too 😀

That said… it’s completely unclear what had been changed from V1.1 to V1.2 (well, U93 being close to the ISA connector gives a hint) and under which circumstances an upgrade is necessary at all.
But if you own a 1.1 and it behaves strange, you should give it a try.

Frankenpal

This is a hack which is very similar to the DesperRAM. It was born out of pure despair, so it’s neither elegant nor very clever – but it works and that’s what counts.

During the “BOZO resurrection“, I had one specific PAL under suspicion to not working correctly any more. That PAL was soldered (i.e. not socketed) onto the board in a very tight spot, so I wasn’t able to cut the pins as close as possible down on the board.
I know, there are special pliers which can somewhat around corners, but my trustworthy Knipex (The pliers maker in the world, full stop.) can’t. So I had to cut the pins right at the PALs package – easy and quick.

The downside is that this method leaves you with a leg-less IC… and if you then decide it might be useful to read-out that IC (like I did) it’s time to slap your forehead :-/
But not so fast, young Padawan. Despair has the advantage that it normally can’t get worse, so nothing to lose. Even you cut the legs off you still can spot the tiny remains leading into the package. So why not trying to replace the amputated legs with artificial limbs!?

My initial thought was soldering new pins to the package, but the remaining connection is way too small to allow anything to be soldered to it but a human hair.
So I used a socket, turned upside-down, slightly bent the legs inward, squeezed the PAL between the sockets legs and carefully soldered the pins to the case-connectors. Finally I put small bits of wire into the sockets empty holes to create new pins to connect the whole thing to my GAL-programmer. Voilá: FrankenPAL

FrankenPAL

Yes, it looks horrible and I was quite sure that this doesn’t work but it just costed me 10 minutes, so what the heck, let’s try read-out that beast.

What should I say? It worked right on the first try… So never despair as long as you have a working solder iron 😉