Recent content by circuit

I need a 2364 ROM burning for my IBM 5150. I can supply the file but I don't have a ROM or compatible burner. I'm aware a few different roms may be compatible, including MCM68764, 27HC641 (if programmed in a certain way), I am also aware of modern replacements such as ROM-EL, but I don't think...

Pictures probably explain it better than I can... I have a PET 2001 with known good video RAM tested elsewhere, it's displaying a character that seems to change according to on whatever's in the top left character of the screen. Swapping main RAM / ROM did not make any difference, nor did using...

Would like to obtain one of these for my 5150 which is sadly badgeless (or rather, incorrectly badged) :dontgeti: (Strangely, mine has the rear case badge on both the front and back. Therefore, I have a rear 5150 case badge if anyone needs it!)

I am not too much of a purist and like boards such as the ones Donni & Nicholas Weite designed for the PET. Does there exist a similar, affordable (or schematic / gerber) for a ROM or RAM replacement board for Apple ][+? I am aware of some solutions, but they are either slightly more than my...

Will anyone give this rust bucket a new lease of life?! http://www.ebay.co.uk/itm/Commodore-PET-2001-Computer-Blue-fronted-low-serial-number-240v-/401176337614?&_trksid=p2056016.m2516.l5255

On power on, a brief drive whirr , the centre LED illuminates and stays illuminated. There is no blinking or flashing of the drive LEDs. I believe the drive is interfacing in some way with my PETs even at a very early level because if I turn it off, I get "device not found" errors. Typing...

I saw this item on eBay; the seller didn't know what it was, and they didn't want to open it up. Obviously some case hacking has taken place, but I wondered if anyone had ever seen such a connector on an ST?

I have a chiclet keyboard that has the typical issue of numerous keytops worn away. I'd like to purchase a better condition one where the key print is legible. I would consider just the caps or a full keyboard, and would also consider a keyboard where *most* of the keytops are legible even if...

I've read that W65C21S , 6821 may be usable as substitutes for the venerable 6520 Can anyone confirm from experience if this is true? Particularly in PET systems

I feel silly asking this question - I managed it with ease a while ago, it's been a while since I needed to do it and I'm on Win 10 now. Last time, I used some VM program but I cannot for the life of me remember which. So far I've tried Virtual box , DOSBox, VMWare player, Hyper V, and none...

I think it's an Atari Falcon. I did once modify an STe to have side ports because I hated the fiddly ones underneath, but the Falcon had them as standard along with the "cutout" around them :

After the excellent PIC advice on the other thread I started I now have a working and highly usable FreHD (and what an excellent device it is, too) I thought I should start a different thread for this one as it's a seperate issue. I've tried reading all the available help documentation I could...

I've built a board and have programmed the GAL, but PICs elude me There are two HEX files in the folder, PIC.hex (132kb) / FatFS.hex (158kb). But from what I see, the required 18F4620 is only 64k, so how do I program this? I'm using a TL866CS which is OK for EPROMS and GALs but as I say I've...

I have a Televideo 920 (same as 912 but with different keyboard) which gives a correct short "beep", when powered on but displaying nothing. Mainboard revision is H The CRTC chip was all corroded / pins broken so I ordered a replacement (thanks, Aliexpress!), so although I can't really do...

I noticed various Apple, Altair, Sinclair, Acorn Atom re-implementations, as well as C64 / Amiga / ST. Some FPGA, some "real" circuits. But it seems nothing relating to Commodore PET. Now, I have ZERO skills to design something like this myself, but I can build a kit, so I would love it if...