SaRuMan-TED 64k RAM for C16 and C116

[MCes]

I will kindly ask you to refrain from posting in the threads related to my products, as I do with yours.

Yes,
excuse me but I was victim of my technical curiosity,
and now that the V1.4 SARUMAN-TED pass the DIAG 264 tests there are not reasons to speaking about it ...

I have "reduced" my previous post because it was not intended for injure your project, but it could be misunderstood.
Ok, now I'll try to be silent....

[eslapion]

Technical detail: This product, like other SaRuMan products, consumes only 5mA of power.

[eslapion]

Just played Slipstream on C16 for the very first time. Most impressive.

https://psytronik.itch.io/slipstream

[eslapion]

With DIAG264...

The handmade prototype of SaRuMan-TED:

[MCes]

Ok, now that you have updated the schematic of V1.4 (now V1.5?) I have no more perplessity about its wellworking,
but I noticed that this patch is done with another gate located into a "single gate chip",
but all it can be done in a more elegant way with a single 74 chip.
I wrote a "pizzino" (see pic) with a possible solution, it's a theoretical schematic but it should work at first shot...

I hope this post will be welcomed.

This solution is based on double decoder '139,
with its A0 input the "Y" half selects which output (Dynamic or Static) will be driven by /CAS-TED signal,
so the switch will select the S-64k or D-16k ram bank.
The second half "X" is used as "LUT" and its /Q0 will be "L" only if the CLK are "L" during a Write cycle,
it will deselect the S-Ram lowering the ram input CS2 (that is active H).
So the "X" half will limit the CAS time to the falling edge of the CLOCK but only during a write cycle.

[eslapion]

I hope this post will be welcomed.

If you see a problem and have a solution to offer, the information is always welcome.

Unless of course, you see a problem and honestly don't know of a solution, you can always mention it too.

but I noticed that this patch is done with another gate located into a "single gate chip",

This solution is based on double decoder '139,

I do see a problem with your solution; both outputs (!Q0 and !Q1) from the second (Y) selector will require pull-up resistors*. Otherwise, this solution seems good. However, I get my PCBs made and populated in China. They only offer CMOS logic ICs and have no 74HCT139 or 74AHCT139 in stock. 74LS139 is not available.

Stock 0 ... https://jlcpcb.com/quote#/parts/compone ... t=74HCT139

Even if they did, the price for a 74HCT139 in SOIC (they don't carry TSSOP) is $0.2450 while a TSSOP HCT00 is $0.1189 and the single gate 74AHCT1G32 is $0.0624 so the price for my present solution is $0.1813 which remains less expensive.

* a solution is to swap your connections of GND to !E and !CASTED to A1.

[MCes]

I do see a problem with your solution; both outputs (!Q0 and !Q1) from the second (Y) selector will require pull-up resistors

It don't need any pull up resistors, "H" on /E input doesn't drive in high impedance the outputs,
but simply it will deselect all of them (deselected line= "H" levels, not 3state..)

http://www.ti.com/lit/gpn/sn74ls139a

[eslapion]

It don't need any pull up resistors, "H" on /E input doesn't drive in high impedance the outputs,
but simply it will deselect all of them (deselected line= "H" levels, not 3state..)

Correct... that tells you how often I use demuxers... I also avoid TTL-LS ICs because they're not available in TSSOP format.

[eslapion]

The new V1.4 boards have arrived in good condition. A few of them were tested and all is OK now.

The new units begin shipping on Monday.

[eslapion]

The version with NO SWITCH (64k all the time) is 13.50$US or 12 Euros per unit + shipping.

[emilen72]

Hi, Do you stil offer the V1.2 for free?
Thanks

Actually it does now.

There was an error on PCB v1.2 and everyone who got that version got a refund. PCB V1.4 is in production.

Since the people who got V1.2 were refunded AND there is a fix, the people who do the fix get a free 64k RAM expansion for their C16.

Thanks!

At your service.

Since my little Chinese friends left me stuck with more than 20 PCBs of V1.2, they are free to a good home. Would you be interested in a few ?

[eslapion]

Hi, Do you stil offer the V1.2 for free?
Thanks

Sure. Just pay for postage.

Any reason why you'd want faulty PCBs ? Want to make a bunch of key chains ?

[Hubi]

Hi,

I'm interested in two SaRuMan-TEDs, one with and one without a switch, shipping to Germany. Could you please PM me for further details?

[orion70]

Hi there, Eslapion is not in this forum anymore.

See HERE.