Booting MS-DOS, CP/M and RSTS/E* on a DEC Rainbow!

[Music] thank you hello and welcome back and I have a problem well if we look around the room I have more than one problem but I have one specific problem I'm going to try and solve today this is my PDP 1183 and it is sitting here turning away talking to a vt320 terminal and that is what this PDP 11 talks to it doesn't have a graphic card or anything like that it talks to a data terminal this is not the only PDP that I have in the room though I also have a PDP 1144 that we're going to get into but it's going to do the same thing it's going to talk to a data terminal over rs-232 so I would need two separate data terminals one for the 1183 one for the 1144 and I don't have any room for a second data terminal in here so the vt320 here would just have to serve double duty I would get one of those little rs-232 switches and switch between inputs for whatever machine I'm using at the time but well like I said I'm out of space and of all the machines in here I don't have a single machine that'll run dos well excluding this machine back here which is a really super special machine that I'm very happy about but we're going to get into that later so for the time being I don't have a single machine in here that'll run dos and I don't have a single machine in here that'll run CPM so if I come across a program that I want to run in DOS or I want to run at CPM I don't have anything in here that can do that so I need to rectify that but a dosbox and a CPM box is going to require two more CRTs and I just don't have space for for that many more CRTs in here so it sure would be nice if there was a machine that could do all three things that I need of it a machine that could be a data terminal a machine that could boot into dos and a machine that could boot into CPM all wrapped up into a single package it turns out that deck built just such a machine it's called the rainbow and here it is it has an 888 processor running at 4.8 megahertz it has a z80 processor running at four megahertz and it has some collection of memory in it I think it can be as low as 64k or as high as 900k I have no idea how much is actually stacked up into this machine that's something we're going to find out it can run both MS-DOS and CPM and it can run both flavors of CPM the z80 version of CPM or the 8088 version of CPM so it is a true triple use machine it can run MS-DOS it can run CPM and it has full on vt100 emulation sounds perfect right well not quiet you'll notice that the floppy drive on the front is an RX 50. this is a very strange floppy drive you actually put two floppy disks into a single full height five and a quarter drive but they're only single sided each and they share a spindle which is really interesting but because they're only single-sided in order to get any form of storage out of it the deck rainbow uses a single-sided quad density so they're stuffing 80 tracks onto a single side of a floppy not only that I believe there's no master boot record which makes writing floppies or reading back floppies to Archive it very difficult although we've got an even bigger problem in that well there's no floppies actually in here it's empty I didn't get any software with the machine so that's something that we're going to have to tackle now there is an extra Drive Bay over here that you can stuff a MFM hard drive into but this particular machine I don't think has a hard drive in it although the controller for that hard drive may be built into it again that's something that we're going to have to find out but this is my solution it's not the best it has to run a very specific version of Dos it has to run a very specific version of CPM but this this gets me both terminals a dosbox and a CPM box all in one very compact package now I know that this system actually does work when it first arrived here I got it from my uh good bit good buddy David in exchange for a vax but when it first arrived here we did plug it in put some power into it and we saw some life out of it so we know that this machine works but well before we get too deep into it I really want to crack it open see what's going on inside of it see both of those processors and give it a solid clean so let's get to work to get the case apart there are just two little pull tabs and no screws at all and then the whole case comes right up straight off giving us full access to the drive bays and the power supply so let's get that rx50 out next by disconnecting the ribbon cable and the power connector then just like the ba-23 chassis you just push the little tab down and it slides right out next let's get the motherboard out out by loosening up the thumb screws then it all slides right out the back like a tray of computer goodness with that out let's work on the power supply next by removing the power cable then the fan cables and then disconnecting the tie-down latch and just like that the power supply lifts right out so let's take a look inside that power supply we can get to it by removing four screws and snipping the zip tie securing the cables then the top rotates off giving access to the inside and then the cables can be unplugged allowing the top to come completely free finally let's pull all of the expansion boards off of the motherboard and again no tools necessary just pop them out of the plastic clips and they come right up easy peasy I am incredibly impressed with the way that deck built this thing aside from the four screws that I took out to get into the power supply up here there's no tools needed to take this entire thing apart down to this level it's very cool very well made but this is our main board you can see we've got our 8088 processor right here and we've got our z80 processor right here really rare to see both of those in such close proximity to each other on a single board but here we go in the top left here it looks like we've got some dram this is probably the original 64k that is populated on here and probably some video RAM for the video display circuitry then we have three ROMs here and some other ICS that I don't quite recognize that are big might be ROMs might be something else but that probably contains all of the built-in code that gets to the boot up menu and stuff like that then around the board they have these really cool big connectors that all of the expansion cards Connect into now this machine only had three expansion cards in it the first expansion card here is the floppy control color it goes on the side over here and that's what our floppy Drive plugs into it does look like we're missing the Winchester controller which would have gone along this top edge here we don't have that so we can't actually get a hard drive into this machine it's going to be a floppy only machine for now but as we move on to the next two cards over here this one right here is the pc100b memory extension and it's populated with 41 256 chips there's nine of these chips so that would be eight bits plus parity so I think that's going to push total Ram up to like 320k or something and then on the far right here we've got a very interesting card it's got a necd7220 which is a graphics controller chip so this is the color Graphics expansion card and it's very interesting that this is in this system because the CRT I'm like 99 certain is the early VR 201 that's a monochrome only CRT so perhaps somebody was upgrading the system and they found the color Graphics adapter but they never got to uh finding the correct CRT to go with it while it's all apart like this the only thing that I'm going to do is try to clean off all of the Dust on these two main cards the two expansion cards over here look brand new so we're not going to do any of those we're just going to try and clean these up and while I'm cleaning those up I'll also clean up the power supply which I pulled out to look for rifas and peering around inside of this power supply I can't find any rifas at all and it looks to be like a really well designed power supply so I'm not going to do anything to this other than just uh blow it out there is a pretty big bend in it right here where the power cord plugs in so maybe something ran into it or somebody was pushing it up against the wall on the power power cord jammed into the back here I might try to straighten that out but you know the whole thing fits in there just fine anyways with the bend and it's on the back you can't really see it so I don't know I might just leave that as it is but but man deck is really killing it with the construction of this machine it is awesome the only thing left to do now is to clean it up put it back together and turn it on to clean the boards off I just use a nice soft paint brush to break all of the dirt and dust loose then I briefly hit it with compressed air to blow the Dust Away being very careful not to hit it with too much pressure or try to get any moisture or anything condensing on there and while I have the air hose out I'll blow out the power supply too next let's give the whole machine a good scrub down starting with the main chassis and I like to use Windex as it works surprisingly well and is really safe on Old Plastics we'll give the rx50 a good wipe down too and it's cleaning up really well then we'll give the main case a good wipe down and there were lots of scuff marks and some discoloration but it looks like it's going to clean up really well next let's get the expansion cards back in starting with the ram expansion then the graphics expansion and finally the floppy controller and they just all pop in and connect up so easy then we'll slide this whole tray of computer back into the main chassis and lock it down with the thumb screws next let's get the top back onto the power supply and I'll just put some new zip ties on to replace the ones I cut earlier then we just set the edge of the power supply in place and rotate it down locking it in place with the tie down latch we'll follow this up with the rx50 which slides right in and then the top just sits straight down and the pull tabs latch into place holding it all very secure we're not done yet though the CRT needs a good cleaning as well the glass is a little smudgy and the back has had something spilled on it at some point in its life also the stand to adjust the angle is not work correctly either so we need to fix that too to get the case off it's just one screw on the back just pop the cover off remove the screw and the whole thing slides free and here's the latch that needs fixing and it's actually not broken it's just missing a few screws is all two new screws go in and it works like a top then a good wipe down to clean everything up and get it looking nice and shiny followed by putting the case back on and giving the CRT face a good cleaning as well and that's cleaning up really nice there we go all cleaned up and looking mighty fine I am really happy with how well this thing cleaned up this is not the original keyboard that came with it the LK 201 that came with it didn't work when we powered this up many many months ago so this is just the keyboard off of the vt320 but it should work totally fine so we'll go ahead and flip the switch here that will put Power on hopefully nothing goes up in smoke it'll take it a couple of seconds for an image to come up on the CRT here we should hear the floppy drive here do some seeking when it does some boot up self-testing stuff there it goes yep we had a beep we should be getting something on the CRT here maybe I hit the uh adjustment pots here on the back oh there we go yeah check that out uh see owner's manual message 24 new memory size 384k I guessed 320k so I was off but [Music] look at that we have a working rainbow 100 with 384k of memory but uh unfortunately we we can't really do anything with it from here I can hit T to get into terminal mode and I can hook it up to my 1183 but really what we really want to see out of this is booting from the floppy drive here which means that we got to figure out how to get some form of software onto a floppy disk so we can try to boot from it so that's our next step we're going to need a floppy drive for this and fortunately I have a spare rx50 that we can use and we need some way to communicate with the laptop and for this I'm going to use a grease weasel to make the pin outs match up though I'm going to use this little D bit floppy adapter and finally I need something to power all of this junk so this spare Corsair power supply should do the trick all right I've got my laptop out and I think we're all set up ready to go I've got a USB cable coming out of my laptop into the grease weasel then we have a ribbon keep cable out of the grease weasel into the floppy adapter then another ribbon cable out of the floppy adapter into the rx50 and all of this madness is powered by a spare Corsair cx-430 power supply that I had laying around and I put a little Jumper in it so that way it turns on as soon as I flip the switch and with this I think we should be able to copy some image disks over to floppy disks this is a little interesting now I found two types of disk images when I was hunting for rainbow software on the internet I found a DOT IMD and a DOT pd0 the dot td0s I think are teledisc formats which are like a weird proprietary format that nobody really knows much about and I'm not going to try and mess with that today that's going to take many more hours of figuring out than I'm prepared to spend but the dot imds should go straight onto the rx50 and so I'm going to use the grease weasel to do this and you could do it all from the command line but I find using a GUI to be much simpler so we're just going to use a grease weasel GUI called Greece weasel gooey it's not really that that crazy sounding all right now that we have the GUI open we'll just select uh right to disk looks like our only serial Port is com5 so we'll hit select on that and then we get this interesting GUI where we have a bunch of options and I think I figured out what most of these should be we're going to do F7 Drive select and leave it at a then we're going to do cylinder sets and instead of having two different cylinder sets 0 to 34 35 to 79 we're just going to do 0 to 79 because we're doing 80 tracks on one side so we'll just uh update that right quick and then we're going to do headsets set of zero and one we're just going to do zero because it's only a single sided drive and then for Disk type we're going to select IMD we'll leave format as unspecified format and then we'll click select file we'll go up and we'll pick a disk image here and we've got a couple imds to choose from here I think we're gonna go with diag that is a pretty solid diagnostic program from what I've heard I've never run it but supposedly deck built really great diagnostic programs for this so let's try to get that writing now we're almost ready to go I do need a floppy disk so I'm going to take a floppy disk and I'm going to slide it into the drive here and then we'll go ahead and close the door on it we'll flip the power on for everything I I think that's going I don't know let's hit launch and see what happens yeah the drive spun up t0 writing track zero writing track one two three four five it's working so far the the real problem here is going to be when we crack track 40. um if it's trying to write dual-sided or we made a mistake somewhere it might crash at track 40. so we're just gonna sit here across our fingers and hope it makes it all the way to track 79 with no problems all right we're coming up on the end track 78 track 79 all tracks verified hopefully that means that it successfully wrote a disc that the rainbow can read but there's really only one way to try out to find out and that is to pull the disc out pop it into the rainbow and give it a go we've got the diag disc that we just wrote in the rx50 that's in the rainbow we're booted up into the main menu screen here I believe I put it in drive a I think that's the top half so we'll try uh pressing the letter A to start from drive a uh yeah it's reading that disk see we got a blinking cursor at the top here It's a Wonderful sound oh all right rainbow 100 diagnostic disc at version 2.0 copyright 1983. and then we have a main diagnostic menu here uh test drives A and B test computer display individual test menu or four install new Diagnostics so let's go to individual test menu we'll do number three here uh and then we'll hit enter on that oh that's cool so we've got two memory tests we have an 8088 memory test and an 8088 z80 memory test let's start with number one here see what the memory test for that does individual diagnostic test memory 8088 system memory size 384k subtest one main memory is 64k our execution count is 2019 18. uh I wonder if that's going to count down for a very long time so we'll just let it go this is really cool all right I I got way too impatient the memory test was taking forever which is good I guess it means that it's testing it pretty thoroughly but man I can't wait that long so I went ahead and wrote two more floppy disks uh put CPM on one and dos on the other let's see if we can achieve the goal that I set out to at the beginning of this video and that is to have a machine that can do three things boot CPM boot toss and work as a terminal so we'll start with CPM uh we'll hit drive a which I think is the CPM disk yeah there we go CPM 86 80 loading there we go version 2.0 copyright 1981 digital research Inc copyright 82 and 83 digital digital Equipment Corporation we just booted CPM on this machine let's do a directory of a see what's in there we've got some the files I guess I don't know there's uh some other stuff going on in here but that's really exciting but that's that's only half the battle so we'll hit setup here and this is how you reset the computer you do a control setup from the setup menu so we'll do control setup that's going to reset the machine um there we go testing should get us back to the main menu there we go let's try to boot from Drive B now I can see it's reading this there we go MS-DOS loading copyright 1983 digital Equipment Corporation MS-DOS version 2.05 uh ooh current date is Saturday 1001 1983. uh yeah sure that sounds like a good date we'll go 10-01-1983 we'll hit enter on that current time just hit enter take that we're in DOS baby if I hit directory on this foreign check that out we have a ton of stuff hanging out in here although I I think it's mostly just you know like check disk and disc copy and utilities but we're fully into Microsoft DOS and we did it without even having to get out of my chair just hit reset and boot into a different drive-through into dos this is a true dual purpose machine that is awesome but we have one more test can we boot the PDP 1183 and use this as the data terminal for it let me uh get that 1183 up on the desk here and we're going to give that a test all right last hurdle we'll hit T to go into terminal mode I'll flip the switch on the 1183 here testing in progress please wait that's coming from the 1183 this thing is absolutely working as a terminal I just heard the MFM drive and that thing spin up there we go fully booted into the PDP 1183 I've learned a little bit since the last episode and we can actually get to a prompt here and if I type dir we can see a directory listing of everything that is on that hard drive and yeah the rainbow is working beautifully as a terminal for the 1183 so there we go full on Triple boot system matter of fact we can just hit uh control setup and then control setup to reset this will take us back to the main menu the 11. 1183 is still sitting there churning thinking that the terminal's just been disconnected and then we'll just go ahead and hit a and uh boot into CPU how cool is that under 30 seconds I went from being a terminal for the 1183 to fully booted into CPM and we could do it again into MS-DOS this is just brilliant I love this machine there we have it the rainbow is 100 working David I want to thank you so much for hooking me up with this machine it's gonna get a lot of use both as a dosbox and a CPM box but also as a data terminal for our 1183 and our 1144 whenever we get around to bringing that machine up I I just can't get over the fact of how quickly you can switch between all three different modes I could go from dos to CPM to terminal mode all in under 60 seconds it's what an epic machine granted it's not the best version of CPM and it's not the best version of Dos and it has its own quirks that kind of led to it being a fail you're in the marketplace but I love it all the same this thing is absolutely epic so I want to thank you guys so much for watching and I hope to see you next time

Channel: Usagi Electric

Views: 34,110

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Id: qPHFnFKulFE

Length: 24min 27sec (1467 seconds)

Published: Sun Jul 09 2023