It’s been a long road to get to this point…but CP/M FTW!
Posted by mdgorelick@reddit | retrobattlestations | View on Reddit | 38 comments
This was a super sad machine when I got it. A bunch of cleaning, spiffy new power supply, lots of video and VCO adjustments…and I now have stable video and it boots from my disk emulator. Next up: upgrade to 128K, FreHD, and maybe a fancy graphics card?
The more I learn about and play with the 4P the more I love it.
Aezetyr@reddit
Gary Kildall would be proud. Nicely done OP.
mdgorelick@reddit (OP)
❤️
RIP Gary.
SamirD@reddit
I've almost never seen an external IBM floppy drive case like that except the one we got with our ps/2! Ours has a red power switch and is still stock. Where did you find that and how did you wire it up to the TRS-80?
mdgorelick@reddit (OP)
I own 3 of the IBM external drive housings. I have a Greaseweazel interface and disk drive in another. This particular one I got for $20 at the Vintage Computing Festival Midwest last year. I took the 1.2Mb FDD out of it and mounted an HxC drive emulator instead. Same connectors. Interfacing to the TRS-80 lineup is really simple. They all use the standard 34-pin Shugart-style FDD interface that the IBM PC uses.
I ran the ribbon cable out the back and plugged it into the FDD interface on the motherboard. It’s really only convenient to do that with the 4P’s outer housing removed.
SamirD@reddit
Oh wow, that's awesome! I forgot that the TRS-80 used the same floppy interface. Our drive has a special cable and controller card in the 30-286 and is only 360k capable. I even tried swapping the drive out for a 1.2, but it didn't work. Something proprietary about the whole setup.
mdgorelick@reddit (OP)
When I got my IBM drives, they had the 37-pin cable that comes with the unit. Probably the one you’re talking about.
There are two different versions of that PS/2 drive—the 360k you had and the 1.2Mb that I seem to keep getting. Since my plan is to take the drive (and that huge cable) out anyway, I haven’t cared about which version it is. I just want the case and power supply. They’re both retro-cool looking and exactly built for my purpose.
SamirD@reddit
Possibly--I forgot what the cable was on the drive side--I can't remember if it was the same big 37-pin or not. I remember is was in the style of rs232/vga but had 3 rows of pins.
Hey if you don't want the guts to those, I would love to have them.
mdgorelick@reddit (OP)
So it turns out the most recent external drive I got is a 360K and has a red switch. Might be related.
SamirD@reddit
Might be! If you've got pics, I could probably tell you.
Longjumping_Push2223@reddit
That's very nice
ddrfraser1@reddit
Man, that looks great. Great integration of old and new.
GhoulL0ver@reddit
epic
GaiusJocundus@reddit
You might like Small Computer Central or RC2014 kits for more CP/M goodness!
mdgorelick@reddit (OP)
I was so happy when I got WordStar running on it. ;-)
sw1ss_dude@reddit
Fun fact: George RR Marti used it to write Game of Thrones
demorcef6078@reddit
That which is dead can never die!
bitwize@reddit
I dunno man, with strange aeons even death may die.
mdgorelick@reddit (OP)
I can see why he chose it. The screen and keyboard are really nice.
bitwize@reddit
Nice! Happy Octandy!
setwindowtext@reddit
You might want to check this out: https://kevinboone.me/cpm-c.html
mdgorelick@reddit (OP)
Thanks for the link!
jon-henderson-clark@reddit
i found this one: https://www.trs-80.com/wordpress/reference/cpm/
i did cp/m on these dual floppy Zilogs: https://d1yx3ys82bpsa0.cloudfront.net/brochures/zilog.z80.1976.102646104.pdf
mdgorelick@reddit (OP)
What a beast that machine is! I wasn’t aware that Zilog made entire computers.
jon-henderson-clark@reddit
The drives needed constant alignment or errors would be thrown. These were the screens for an answering service, so the drives were always spinning. I'd sometimes have to mis-align a drive to copy off data.
mdgorelick@reddit (OP)
Just got a chance to read through that page. C programming in CP/M sounds like just my sort of geeky, retro rathole ;-)
vinciblechunk@reddit
I'd also like to go on the road to CP/M, but mine is probably going to go by way of MSX
mdgorelick@reddit (OP)
One of the cool things about the 4P is that it’s designed specifically to run CP/M while retaining compatibility with the Model III. CP/M requires RAM at $0000, which is where the TRS-80 family puts its ROM. The 4P has no ROM at that location, but with a specific boot disk you can load the ROM, hit reset, and it works like a Model III.
-jp-@reddit
Man, I love how well the floppy emulator fits with the aesthetics of the rest of the machine. Without zooming in, the only hint that something was out of place was the LCD.
mdgorelick@reddit (OP)
Thank you, that’s very kind! I’m thinking of replacing one of the mechanical 5 1/4” drives with a disk emulator. That and “FreHD” would really put this 40 year old computer into the modern age.
firewi@reddit
Hey, I know Lotharek. Nice guy, done a lot for the retro Atari scene and vintage computing in general.
mdgorelick@reddit (OP)
I’ve bought stuff from him a couple of times now. Most recently a FujiNet for my 8-bit Ataris. What a great product.
alwayzz0ff@reddit
Awesome
DeepDayze@reddit
Then can it play Doom?
mdgorelick@reddit (OP)
Maybe with the “grafx” card? It’s still monochrome, though. :-)
aManandHisShed@reddit
I guess you've routed the internal floppy cable out of the box to you emulator. Are you going to get the floppy drives going?
mdgorelick@reddit (OP)
I’m going to try to. It would be pretty straightforward to connect the HxC disk emulator and one of the physical drives at the same time so I could boot on the HxC and use that image to create hopefully-working diskettes with the physical drive.
mdgorelick@reddit (OP)
I’m hoping to have one emulated (drive 0) and one physical (drive 1) once I figure out what works and what doesn’t. I also plan to put a FreHD and maybe the newfangled graphics card in it.
100-100-1-SOS@reddit
Looks great!!