Page 1 of 2

Does anyone have an original CEGMON?

Posted: Wed Apr 24, 2019 8:21 pm
by Steve Gray
Hi,

Does anyone have an original CEGMON rom for C1? I believe the one here has been modified. I peeked the initial power-on values for the "window" parameters and they do not match the ones in the manual (for C1/superboard). The top line is too high on my monitor and when I poke in the correct values the top line moves down. Also, the CTRL-Z key does not seem to clear the screen.

I want to take the source and adapt it to the ACME assembler, which I use (it's cross-platform) and will eventually be able to build from the source, but I'm not at that point yet.

So, if anyone could dump a known good original CEGMON and compare it to the one in the downloads here that would be appreciated!

I did not check the C2 or UK101 roms so I can't comment on those, but it would be nice to verify that those are correct as well.

Steve

Re: Does anyone have an original CEGMON?

Posted: Wed Dec 28, 2022 4:46 pm
by IanB
Steve Gray wrote: Wed Apr 24, 2019 8:21 pm Does anyone have an original CEGMON rom for C1? I believe the one here has been modified. I peeked the initial power-on values for the "window" parameters and they do not match the ones in the manual (for C1/superboard). The top line is too high on my monitor and when I poke in the correct values the top line moves down. Also, the CTRL-Z key does not seem to clear the screen.
Did you ever find a genuine CEGMON dump for the Superboard or UK101?

I've looked at the dumps on here and other places like marks-lab and the screen window dimensions (TOP and BASE) don't match the manual and aren't really suitable for use on actual monitors due to the top lines being off the top of the screen for the Superboard or in the case of the UK101 the screen window is only 48x14 instead of 48x16 as used by the original and new monitors and as indicated by the values in the CEGMON manual:

window.png
window.png (42.34 KiB) Viewed 1915 times

There is a 48x32 version for the UK101 but that looks like it has screwed up interrupt vectors.

It's easy enough to tweak the values to fix this but I'm not sure if these changes were made more recently by adapting a dump for another model like the C2 or C4 or if they were made back in the 80s by the original users of the ROMs that got dumped but either way I don't think they would have been shipped like that as they would have been unusable for many people.

Re: Does anyone have an original CEGMON?

Posted: Wed Dec 28, 2022 5:06 pm
by Steve Gray
No, I have not found any additional rom dumps. I did complete my ACME assembler conversion here:

https://github.com/sjgray/OSI-monitor-roms

So you can assemble different versions as per your requirements....

Steve

Re: Does anyone have an original CEGMON?

Posted: Wed Dec 28, 2022 9:04 pm
by bxdanny
One other thing I've noticed is that the CEGMON version for C1P built into WinOSI uses Control-Q rather than ESC to copy characters from the "edit cursor" onto the line being entered. So clearly, it was adapted from the UK101 version, since that system's keyboard doesn't have an ESCape key. The C2/4/8 version does use ESC.

None of the versions I've seen actually clear the screen when Control-Z is pressed, and I'm not sure any version actually did. I did see an original C1 copy of CEGMON back in the day, and I don't *think* that it actually did that. But it did use ESC to copy characters from the edit cursor into the input line. And of course, PRINTing the Ctl-Z character through CEGMON's output driver DOES clear the screen.

Re: Does anyone have an original CEGMON?

Posted: Wed Dec 28, 2022 9:10 pm
by Steve Gray
I'm still fuzzy on details, but there are differences between the OSI BASIC and the UK-101 version. If I understand correctly the OSI BASIC filters keystrokes somehow differently. The UK-101 lets them through. So maybe CTRL-Z would work with UK-101 BASIC...

Steve

Re: Does anyone have an original CEGMON?

Posted: Wed Dec 28, 2022 11:58 pm
by IanB
bxdanny wrote: Wed Dec 28, 2022 9:04 pm None of the versions I've seen actually clear the screen when Control-Z is pressed, and I'm not sure any version actually did. I did see an original C1 copy of CEGMON back in the day, and I don't *think* that it actually did that. But it did use ESC to copy characters from the edit cursor into the input line. And of course, PRINTing the Ctl-Z character through CEGMON's output driver DOES clear the screen.
I just tried the UK101 version and Ctrl-Z does clear the screen although that also results in a syntax error when return is pressed after that so it isn't removed from the line input being parsed by BASIC.

Re: Does anyone have an original CEGMON?

Posted: Thu Dec 29, 2022 4:23 am
by Mark
UK101 BASIC allows input in the range ^K to <DEL> $0B to $7F
OSI BASIC allows input in the range <SPACE> to | $20 to $7D
The differences are in the BASIC1 ROM code around $A351

So the ^Z entered with UK101 BASIC gets echoed to the screen and is handled as screen clear, as well as getting put in the BASIC line buffer
The same attempted on OSI BASIC does not get through to be processed. However as mentioned earlier printing ^Z will be handled by the screen code on both systems.

This extended input is used by some UK101 programs like Super Space Invaders to allow control character graphics in DATA statements, which are filtered out if loaded on C1P with OSI BASIC.

I do have an "original" cegmon from C8 system, but nothing for C1, so no idea what the original screen values were.
I find the Cegmon with the "Emacs-like" key bindings to be a lot more intuitive.

So besides Cegmon, there was the C1S from Aardvark Technical Services, which I recently realized was its own thing, and seems to have escaped much attention. Anyone have any info on that? I used to assume it was just a version of Cegmon until I actually loaded it up. The only info I have was taken from an advertisement, or gleaned from a disassembled listing which I believe was provided by Ed years ago.

Cheers,
-Mark

Re: Does anyone have an original CEGMON?

Posted: Thu Dec 29, 2022 9:05 pm
by Steve Gray
I just checked my purchase list (http://www.6502.org/users/sjgray/comput ... chases.jpg)
and apparently I have a "C2E" monitor rom. All this time I've forgotten about these things. I will have to see if I can find it...

Steve

Re: Does anyone have an original CEGMON?

Posted: Mon Jan 02, 2023 3:46 am
by Steve Gray
No luck finding the C2E ROM. But I think I know what happened. Back in the day I got the ROM for my C4P cassette system. Later I bought a floppy drive and controller and asked someone at the TOSIE group to help get it working. I think they swapped my C2E ROM with a standard OSI rom and configured it for me. I guess at the time I never thought anything about it.

Steve

Re: Does anyone have an original CEGMON?

Posted: Wed Jan 04, 2023 6:29 am
by bxdanny
C2E was Aardvark's name for the C2/4/8 version of CEGMON, and that version apparently IS the one available here and/or on Mark's site, and incorporated into WinOSI. While I don't know for sure where the page that would otherwise be $FCxx was remapped to, my guess would be $F6xx, since $F4xx and $f7xx often contained PIAs, with $f4xx in particular being the parallel printer port.