deramp5113's latest activity

The same circuit is used for reading both the bottom head and top head of the drive. The same applies to the write circuit. Since top...

Martin Eberhard dumped the ROMs from two of these boards that he has: an 88-RBM and an 88-RBM II. The ROMs on the two boards had similar...

I just realized today that the only copy I've ever seen of the ROMs from the Altair 88-RBM board have at least one modification versus...

Based on testing a Model 28 Teletype I'm working on, I just figured out that TeraTerm does not send the LF of a CR/LF ending if the...

I imagine I've re-invented the wheel, but I created a utility to convert Intel hex files to .ent files for the Sol-20. The utility...

Does anyone happen to have a TLF4C60801M flyback transformer for a Panasonic 9” monitor? Or know an acceptable substitute? This is for a...

Today, I did a bit more work on disassembly of those sections of EXEC involved in disk I/O. It expects several functions not present in...

Interestingly, the native format of executable files in FDOS actually is Intel hex, but I haven’t gotten to the point of loading files...

OK, that’s an important answer. As I mentioned, the FDOS-III manual says the support PROM is at C000 (for the Poly-88) and the support...

Did the disk label show “FDOS-III” or just “FDOS?” Did you see anything in the content that might indicate FDOS-III in particular? Mike D

Lol, since a tantalum cap failure is either explosively obvious, or a highly common short (especially on the higher voltage supplies)...

Yep, it’s almost always a tantalum. This time it was a “silent” tantalum failure/short on the CPU board without an explosion. The first...

I have the FDOS support PROM source recreated and can now reassemble the PROM at B800 as required for the Poly-88 FDOS files found on...

Looking at an automated disassembly of this EXEC file, I can see it is expecting the Poly-88 version 4 monitor, and since the files all...

Ok, that makes more sense - it’s an archive of binaries for FDOS-III saved in Intel hex format on an ISIS disk. The EPROM on the...