Jim, yah, I think we will find things that can be improved. for a next board spin (I only ordered 30 boards initially) I can add a track/ jumper. nice idea to "power" the DB25 port also!
The issue of how the fonts look is a bit beyond my pay grade for now. What is implemented is exactly what was done in the original design. The version of the design available on Tindie https://www.tindie.com/products/petrohi/geoffs-vt100-terminal-kit/ has improved firmware, but I haven't made that M100 friendly. The font has grown on me ;) On Fri, Oct 16, 2020 at 12:09 PM Joe Grubbs <[email protected]> wrote: > Awesome Jim! I can't wait until mine gets here > > ------------------------------ > *From:* M100 <[email protected]> on behalf of Jim > Anderson <[email protected]> > *Sent:* Friday, October 16, 2020 12:00 PM > *To:* [email protected] <[email protected]> > *Subject:* [M100] having fun with MVT100 > > On a more uplifting note, I received my MVT100 in the mail last week and > I've been having a blast with it! I thought I'd share a few things which > others might find helpful: > > I added the jumper for the BCR TTL serial hack to the machine I've been > using for my REXCPM (the old SOD hack, because I'm unlikely to go the Z80 > route and didn't want to be bothered patching things). While I was in > there I also ran a jumper to supply VDD (which I picked off from a nearby > via which supplies pin 9 in the BCR port) to pin 22 on the RS-232 port - > this is the Ring Indicate signal from a modem and isn't connected to > anything in the M100, but more importantly, it maps to pin 9 when you use a > DE-9 adapter. I was inspired by Stephen's post about adding a jumper to > the MVT100 to power it off pin 9 (which I have also done) and which > reminded me that my old Bluetooth serial adapter also is capable of drawing > power from pin 9. This way, I can run the MVT100 off either the BCR or the > RS-232 port and it'll receive power. > > If there's a future need to revise the MVT100 board design, it might be > useful to add a trace and a jumper to allow the user to easily > enable/disable power draw from pin 9 - the way it is now, I'm not sure > whether Bad Things would happen if I tried using the board as a USB serial > adapter while it was connected to my M100, since that would common the > M100's VDD with the USB power supplied by the PC... > > A note on screen resolutions: I had not even thought about this until I > got it and started playing around with it, but the text font the MVT100 > uses can look absolutely hideous when it's being scaled poorly by an LCD > monitor. This isn't specifically an MVT100 issue - LCD monitors often > wreak havoc on text when they are scaling from a non-native resolution, and > it's something I'd just forgotten about because it's been so long since I > had to drive an LCD at its non-native resolution. My original plan for my > MVT100 was to use it with an older NEC 15" LCD I had which is native > 1024x768 - too low to be useful for a PC, but I thought the compact size > and 4:3 aspect ratio would make it a perfect terminal display. Alas, it's > actually almost the worst thing to use, because the MVT100 output is > 640x480 and that means there aren't enough pixels to do an acceptable job > of scaling, giving characters that alternate from skinny to fat as you read > down a line of text... > > I also tried with a 1280x1024 LCD on the theory that I might be able to > tweak the pixel clock settings in the monitor and get it to map at least > the horizontal pixels 2:1 but this monitor doesn't let you tweak very much > (it mostly relies on the auto-adjust routine). I got it looking better > than the small LCD but I still wasn't very happy with it (and it still > didn't look as good as sending it into a bit 1920x1080 LCD). > > Of course, it looks the best by a long shot when you send it into a good > old VGA CRT, which arguably is the most retro-looking solution of all, and > lucky for me I never did throw away that little paper-white monochrome VGA > monitor I got back in the 90s (yes, I said monochrome VGA!). It's kind of > perfect for this - it doesn't even pretend to represent all colours, it > only uses the green signal (which is all the MVT100 is jumpered to output > as I received it) so it all works out almost as if it was meant to! > > One other thing: I don't know what is limiting the display output speed, > but when I started using the BCR at 57600bps I was expecting the display to > update faster and it seems like it actually is the exact same speed as it > was on the serial port at 19200bps. From past experience using dumb > terminals I had been feeling like even the 19200 output was displaying a > bit slower than it could (it felt like 9600) and I'm wondering if this is > just a result of the processor having to take turns between executing > program instructions and bit-banging each output byte. Please don't take > this as a complaint about it being slow - the speed is fully in keeping > with my expectations for the platform, and it's lightning-fast compared > with the internal LCD :) I just wonder what is limiting it because I know > the M100 is capable of faster data transfer... (speaking of which, I'm > still dying to have access to the high-speed large-packet data transfer > capability for backing up and restoring REXCPM) > > Anyway, it all works great and I couldn't be happier with this solution! > Many thanks to Stephen for sharing your genius ideas with us! > > > > > > > > jim > >
