durgadas311's latest activity

E5 is EBCDIC for 'V' - the last value written to data sectors after/while Verifying them. If you look at the first track/sectors of a...

I was in high school when I was introduced to our Honeywell 2040, early-mid 1970s. So, a "kid" by most definitions but definitely "not...

CP/M is basically indifferent about the details of the console, that being contained within the BIOS created by the vendor for the...

Oh! That the lit buttons form an "H"... interesting and curious.

Also, DRI shipped a "reference implementation" (Intel MDS-80?) and created the de facto-standard 8" SD floppy format of CP/M. That...

Are you talking about the fact that it does a lamp test? I saw that in documentation, somewhere, such that I included it in my simulator.

I'm guessing the Honeywell consoles used a different print head - they had different characters, and different encodings. I also seem to...

I used to become entranced watching the H2040 console typewriter (H220-3) print mechanism. A rectangular block of typefaces would dance...

This does sound like microcode, with the instruction width of (maximum) 56 bits. 64 words is not very much program, but we don't know...

One of the reasons I suspected the ROM was faded or did not read correctly is that there is a non-sense instruction in the RST 7 code...

Now that I know there is a Z80-SIO, I found the init code for the SIO. Channel B is setup for typical Async RS-232, and it appears to be...

It appears to be using ASCII, at least some places. I see a routine for converting an ASCII character to hex, and that is called by a...

I see one place where it checks for an ASCII character between 'A' and 'T' and then indexes into a jump table and executes the...

I spent a lot of time dissecting Wang programmable calculators (and related machines) from the 1969-1974 era. The "CPU" is generally...

Technically, "common memory" is not part of any bank. But generally it is what the system resets with and never changes. I'm not...