Recent content by hideehoo

Ordered a couple INS1771's from this eBay seller and they came in today. Seem to work fine. I do have one weird issue unrelated to the disk control chip used where some Chinese sourced 74LS242's claiming to be TI chips from Portugal (and it's even molded on the back of the chip) refuse to...

Another example using custom PCB's. John has used this design across a couple of his Coleco ADAM DDP replacement products. https://lundyelectronics.com/product/internal-fujinet/ https://lundyelectronics.com/product/internal-ade-pro/

Yep, the the Cext pins on the 74LS123's (and their associated caps) were isolated from ground in the video section. When I do a v1.1 validation build I'll try 74LS221's since it also requires a change in the capacitor and resistors values that make up the RC network there. There is no...

Almost done with v1.1. Fixed all the errata, added some additional through hole pads between the various 5V and ground bars up in the video section to make it easy to add some additional caps (nothing is labeled, just there if you need them), and I did add the ability to easily do the 4Mhz mod...

Just noting the smaller 9" monitor option only takes 15V http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/8032/8032051-3.gif I designed this mod for the larger 12" monitor that takes 21V

Nice, and a great price, please let us know how it works out. I picked up this guy from eBay while I was waiting for my FD1771's from China, but unfortunately it didn't work. https://www.ebay.com/itm/224738121982 Not sure if the J and N variants are different (datasheets are a little thin on...

I've had a 74S04 in U11 on the new board and haven't really noticed a jitter issue on a CRT monitor. Original board had a plain 7404 for U11 and also seems fine (on a proper CRT). The extra caps are really just a belt and suspenders approach in case they are needed by someone. The 4 MHz mod...

Blinken Board Yes, I'm driving the outputs high directly from the 74LS243's since there isn't a handy 5V source close by. With 470R resistors, each output is ~7mA for a total of 28mA per driver. Datasheet IL is -15mA at high (per output? total?) but I let one sit for an hour and nothing...

Tonight's random KiCAD projects are a composite video board if you don't want to make your own cable And a slimmed down version of the fd50to34 adapter that plugs directly into the 50 pin floppy header Next up is a sixteen LED blinkem board for the J5 header to give the CTC and extra PIO...

All ten boards (including mine) are out in wild now, so far only @gekaufman and I have them built and working that I know of. Don't have any 72LS221's in stock, so no idea on how they work, on my next order from UTSource currently. For 4116's, even UTSource is kinda spendy these days, so I...

Thanks to everyone who picked up a v1.0 board on VCFMW, hope your build goes well. Now it's time to plan for v1.1. Here's my initial thought on changes... 1. Fix all the v1.0 errata (missing traces), including the factory bodge needed on U73 (the video ROM). 2. I had a hard time getting a...

Fixed the screen corruption issue on the original, couple of data line bits at U71 (74LS243) were not happy. Corroded chip legs + corroded single wipe socket was just not happy, even after cleaning. Swapped in a new 74LS243 and now completely working. The Ladder tournament can now commence.

At VCFMW, get yourself a v1.0 board for cheap 😀

The software package for HxC Floppy Emulator, https://hxc2001.com/download/floppy_drive_emulator/ Load the IMD and then export as IMG. Should be exactly 256,256 bytes when correctly exported. Less than $5 to get five PCB's of https://github.com/pski/fd50to34 shipped to your door in the US...

Swapped all the vintage chips in my reproduction with news/used ones from UTSource (still working yay). Took the cleaned up original board, replaced the zener at VR1 that was dropping -12V to -1.76V instead of -5V, and then reinstalled all it's original chips. It has the 4MHz mod that uses...