The Sinclair QL Forum

Silvester wrote:Not sure I understand the 3V3 supply arrangement, referring to image in last post: Square pad in group of three pads is Ground. Square pad next to power connector is +5V. With link in place (as shown) +5V is fed to other two round pads.

For 3V3 conversion replace link with 2V4 Zener diode: cathode to +5V square pad, anode to pin 2 (Vout) and pin 3 (Vin), with ground on pin 1 (ADJ/GND) of regulator.

(I can only assume there is a link somewhere to be removed between pin2/3.)

I don't fully understand. Let me rephrase:
1. Place Linear Voltage regulator on the three adjacent pins, heatsink toward PCB border.
2. Place Zener Diode with cathode toward power connector, instead of the wire used on Q40.

Silvester wrote:BTW, Peter, if you can recall, did you make use of Presence Detect (1-4) on 72 pin SIMMs ?

Yes I recall, and no I did not use presence detect.

Thanks for diagram, that helped explain what is going on in the hidden PCB layer, that makes a lot more sense

Now let's hope your CPU socket allows easy addition of the 68060's extra pins.

All this 68060 talk makes me so sad that the Q60 can not (nicely) live with modern flatscreens.
I'm constantly tempted to do something about it, but the effort would be very high.
The final Qx0 board was designed 25 years ago, and of course I forgot all details about timings etc.

What makes a decision so difficult, is that every high performance video card for the original machine would
- require extra wires to be soldered, a simple plug-in solution is impossible (ISA bus only 16 bits wide. ROM sockets 32 bits wide, but lacking several control signals)
- be so complex that it probably costs 70% of the design time for a completely new machine

Slight identation into socket on left edge unavoidable due to video RAM making it awkward to gain horizontal access. Backlit so empty PCB holes clearly visible. But thankfully all CPU pins remained straight

Once the regulator and Zener diode are in place I'm guessing to revert it to 5V it is OK to just put link across Zener diode? Also what voltage Zener 2V4 or 2V7 ?

I read elsewhere overclocking 68060 rev.6 (71E41J) to 80MHz may require up to 4V5 to CPU, would it be inappropriate to consider installing adjustable LT1086 on my Q40?

So by my reckoning I'm going to need 25 (26?) sockets:

Peter wrote:Now let's hope your CPU socket allows easy addition of the 68060's extra pins.

Tried dropping in normal turned pin sockets, but don't seem to be same quality, the cone is less forgiving of misaligned pins (bottom left is newly inserted, others are original).

Peter wrote:All this 68060 talk makes me so sad that the Q60 can not (nicely) live with modern flatscreens.
I'm constantly tempted to do something about it, but the effort would be very high.
The final Qx0 board was designed 25 years ago, and of course I forgot all details about timings etc.

Too much effort for too few Qx0 users I still have 15" Vivitron multisync still working good as new (occasional repairs only required new solder - due to mechanical/thermal or HT stress).

Peter wrote:What makes a decision so difficult, is that every high performance video card for the original machine would
- require extra wires to be soldered, a simple plug-in solution is impossible (ISA bus only 16 bits wide. ROM sockets 32 bits wide, but lacking several control signals)
- be so complex that it probably costs 70% of the design time for a completely new machine

At least Q40/Q60 saw the light of day and are still in use , unlike some other ambitious (though desirable) failures (http://powerphenix.com/rodolphe.czuba.f ... erview.htm)

Silvester wrote:Tried dropping in normal turned pin sockets, but don't seem to be same quality, the cone is less forgiving of misaligned pins (bottom left is newly inserted, others are original).

Still it looks quite good! Personally, I would do it this way.

Silvester wrote:Too much effort for too few Qx0 users I still have 15" Vivitron multisync still working good as new (occasional repairs only required new solder - due to mechanical/thermal or HT stress).

You are lucky. Mine has lost too much brightness.

Silvester wrote:At least Q40/Q60 saw the light of day and are still in use , unlike some other ambitious (though desirable) failures (http://powerphenix.com/rodolphe.czuba.f ... erview.htm)

Apparently that one died lacking OS support. That is why the Q60 was especially designed with
- Hardware restricted to existing or simple to write OS support (e.g. no PCI but onboard graphics)
- Basic driver code written by myself
- Utilities to demonstrate fully working machine
- Debug loader written by myself to make things easier for OS authors.

Also, I did my best to connect with more OS-level software authors than just Tony Tebby.
So even if SMSQ/E failed, there would still have been QDOS Classic and Linux thanks to the wonderful work of Mark Swift and Richard Zidlicky.
The first OS for the Qx0 was QDOS Classic, by the way.

Silvester wrote:Once the regulator and Zener diode are in place I'm guessing to revert it to 5V it is OK to just put link across Zener diode?

Yes. And remove the (output connection of) regulator, of course.

Silvester wrote:Also what voltage Zener 2V4 or 2V7 ?

Both are fine.

Silvester wrote:I read elsewhere overclocking 68060 rev.6 (71E41J) to 80MHz may require up to 4V5 to CPU, would it be inappropriate to consider installing adjustable LT1086 on my Q40?

For the rest of the board, any CPU supply voltage from 3.3 to 5V ist okay. You are probably aware that 4.5V massively exceeds the maximum ratings and therefore shortens the lifespan of your CPU, so that is your individual decision. Please keep in mind that very few SMSQ/E programs can use the FPU. So you might be better off with a 75 MHz non-FPU version, if not interested in Linux.