More “don’t ask” links. I was tinkering with emulators again, and ran across this comprehensive page on the Z80 and the various DRI operating systems that ran on it. Nice emulators and lots of software and archived information.
Z80pack – Z80 Emulator and Crossassembler for UNIX
Addendum: The Z80/CPM were CPU/Operating systems back in the days before PCs, just in case you are too young to know. Back then, using a computer looked something like this:
And yes, the IMSAI 8080 had an 8080 inside it, not a Z80.
Bloody heck those were the days when pc were simple and worked 🙂
Cheers
Yeah…. til someone walking past the table jostled the RAM pack with the vibration of their clunking feet and it all died.
Or you tried to enter data equivalent to more than four or five screenfuls of text on a modern display (or a couple of 256-colour icons).
Or in this case it seems, tried to do anything useful with it at all other than make an LED flash in sequence, which is the sort of thing that toy circuit boards were more than capable of in my youth (and i’m pushing 30 these days :p)
Mind you that’s maybe unkind given that the Imsai had one of the few home-user CPUs actually weedier than the Z80 😉 That said, I’m ALL about the 16 bit micros (though it’s not enough to even drive the display I’m using now, you can get a lot done in 1mb and 8mhz / half a MIPS), and if this link had been the opposite of what it is (and therefore what I was googling for) it would be epic …. ie Unix ON a Z80. Possible? I do wonder, given the sheer stoneageness of the machines it was first coded for…
In a former life (actually two lifetimes ago) I had an Imsai 8080 chassis but the CPU board was from California Computer Systems and it was fitted with a Z80.
You could do a lot with a 4 MHz processor and 64 Kb of RAM but it could be tricky. I had one customer running his inventory control and billng systems on a CP/M 2.2 system (not the Imsai) with a 5 Mb hard drive! Businesses do not need colour graphics and sound so these systems worked very well.
CP/M 3 was a significant upgrade if you had hardware capable of bank switching. With CP/M 2.2 the operating system occupied a significant portion of the address space (maybe 12 Kb) but CP/M 3 gave 10 Kb of that back by keeping most of the operating system in an alternate memory bank. It meant you could run larger programs before having to resort to tricky techniques like overlays.
The biggest problem of CP/M was the lack of standards for things like terminals and floppy disks. When the IBM PC came along, all of a sudden there were (de facto) standards, bad ones perhaps, but standards nonetheless.
It was a lot of fun programming for these quaint old systems.