Hmmmmmm interesting suggestion. I will have to have a look at his full schematic. :)

I was also wondering if we couldn't borrow a circuit idea from Todd's ELFish design to perform the same "boot swap" function and reduce the chip count while we're at it? That is, replace the NOR gate

I assumed the resistor was simply a pull-down for when 'RESET' returns to '0' (when 'CLEAR' goes to '1'). I was wondering if the capacitor would affect the rise and fall times of the signal applied

That’s a clever technique! --- P. Todd Decker 913-284-8814

From looking at the circuit, the resistor and capacitor create a short delay after reset that causes the ROM to appear at $0000 instead of the RAM. The ROM also still appears at $8000 (as A15 is

Very nice variation and execution of Josh's design. May I ask you or Josh what C13 (the 0.01-uF cap') in the RAM/ROM Flip-Flop Boot-Swap circuit does, please? TIA... Mike

Thank you, Gentlemen. I found a cache of these chips and was hoping they were compatible. Oh well...

see my post about my J-VIP which may be right up your alley. :) schematic and pic in there. :)

Bravo, Walter!

Hi there, i was missing my JVIP, so I decided to pull it out and start playing with it. Out of the corner of my eye, i noticed a couple of 32k Non-volatile ram chips, and decided to swap one into my

well done.   do keep is all posted on how this goes    clyde

Hi, Maker Faire Tokyo 2020 will be held in Tokyo this weekend. https://makezine.jp/event/mft2020/en/ I will be introducing COSMAC and exhibiting my homebrew boards. You can find a description of the

If you blow up the picture a little, you see that we have a CHIP-8 program which draws the square. It would be nice to know more about this product.

Hi Mike - Although they appear to be pin compatible, they are not functionally equivalent. The pin 18 on the 2101/CDP1822 is an Output Disable which controls the output tri-state buffers. On the

David Schultz wrote: Ah! No CMOS loading problems there. Lee -- A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away.

フライヤーが届きました。#MFTokyo2020 #COSMAC研究会 https://twitter.com/kanpapa/status/1309810302234501120/photo/1 Something interesting happening.. wish I knew what!

If changed to HC, then the 47K will work just fine.

MC14495 latch and hex to seven segment decoder -- http://davesrocketworks.com David Schultz

It doesn’t use TILs, it uses a common cathode 7-segment LED display.

P Todd Decker via groups.io wrote: I haven't looked at the RC1802 schematic closely. But the diode OR gates in the original PE Elf used 47k pull-down resistors. Since they all drove CMOS inputs, it