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Thread: Most "accessible" CP/M Machine

  1. #31

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    Quote Originally Posted by Plasmo View Post
    I added a blank board plus a EPM7064S already programmed. So you just need to add a RAM and Z80 to have another working board. I hope you & you dad can have a father-son project together.
    Bill
    I just meant it was a shame since it seemed like you were very excited to have broken through to 29MHz with your design, I hope you didn't take it like I was complaining! I'm sure we will enjoy the hell out of it at any clock speed

  2. #32
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    Quote Originally Posted by maxtherabbit View Post
    I just meant it was a shame since it seemed like you were very excited to have broken through to 29MHz with your design, I hope you didn't take it like I was complaining! I'm sure we will enjoy the hell out of it at any clock speed
    Oh no, I don't see your comment as your disappointment; I'm more disappoint myself that 29.5MHz is not practical. The design is small and simple with minimal bus loading so it is not unreasonable to overclock aggressively, but as soon as extra loadings are introduced, such as with backplane & expansion boards, it won't run any more. I can still brag about it, but it really won't be useful for general uses. I included the extra board because I hope you can work with your dad on a project on this holiday season.
    Bill

  3. #33

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    I have no experience of this offering but as given this link the other day https://rc2014.co.uk/ and it looks interesting.

    Pete

  4. #34
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    Quote Originally Posted by maxtherabbit View Post
    Re the TRS-80 and Kaypro: it seems that both of these machines use single sided, double density 5.25" drives - so am I correct in thinking I could write single sided images with IMD onto regular DS, DD disks in my IBM 360kB drives to be used on said machines?
    Yes, both of those machines should be reasonably easy to generate disks for with a PC floppy drive. (And standard DSDD disks will work fine.)

    Personally I'd recommend a Model 4 over a Kaypro because when you get tired of CP/M the Radio Shack machine will also run the vast library of Model III TRS-DOS software, which among other things includes some far-better-than-you-might-expect video games. I don't really want to say anything bad about CP/M, it earned its place in history, but truth be told it... might be kind of boring to a casual audience. Roughly speaking if you've ever owned a DOS PC with a text-only MDA monitor you've already pretty much had the same experience.

    Edit: A far-out way to *kind* of have a CP/M machine is to fit an XT-class PC with a V20 CPU and run something like 22nice. I spent an afternoon playing with a CP/M version of Wordstar on my Tandy 1000EX and it works. (Although only from a floppy disk, this particular program did *bad things* trying to run from the hard disk.) It's an interesting stupid pet trick, at least.
    Last edited by Eudimorphodon; December 16th, 2019 at 12:42 PM.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  5. #35

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    Well, in that vein, if you want a CP/M machine with a massive alternative library (including some other far-better-than-you-might-expect video games) you pretty much described the Commodore 128 ...
    I use my C128 because I am an ornery, stubborn, retro grouch. -- Bob Masse
    Machine room updated for 2019!: http://www.floodgap.com/etc/machines.html

  6. #36
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    But a TRS-80 Model 4 will run CP/M about twice as fast as a Commodore 128!
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  7. #37

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    If you're looking to build your own, the EasyZ80 is a simple through-hole design with available parts and RC2014 bus connection (to connect a CF card adapter, for example). It boots to ROMWBW with 2 types of BASIC, CPM 2.2, ZCPR, Forth and a monitor, and can run FUZIX from a CF card. The board itself has battery-backed RAM so you can upload programs via xmodem.

    Took me about 3 hours total to build a few months ago. With the board and preprogrammed GAL & flash from Sergey and all of the other parts from Mouser, I think the total was around $80~ for everything necessary. You could shave off a significant portion of that by buying old stock or pulled chips, and programming the flash and GAL chips yourself.
    https://github.com/skiselev/easy_z80
    https://www.retrobrewcomputers.org/d...boardinventory

  8. #38
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    If you're going for vintage hardware and want to run real floppies, make sure anything you get takes common media: soft sector 5.25" DSDD is probably the most ubiquitous from the CP/M era. Machines like the Amstrad PCW8256 are neat and capable, but finding 3" CF-2 disks can be a pain in the USA. Similarly, the H89 is a neat machine but many (most?) come with a hard sector controller for the internal 5.25" drives, and hard sector media is getting hard to find anywhere.

    The Kaypro line is a good choice, as is the Tandy Model 4. I've heard it said that the most numerous CP/M computer was actually the Apple II line with a Microsoft Z80 SoftCard (or functionally identical knockoff). S-100 stuff is neat and usually my go-to for CP/M currently, but there will definitely be tinkering! Vintage single boards like the Ampro LittleBoard make for super nice systems, but they're both rare and expensive nowadays.

  9. #39

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    Quote Originally Posted by glitch View Post
    If you're going for vintage hardware and want to run real floppies, make sure anything you get takes common media: soft sector 5.25" DSDD is probably the most ubiquitous from the CP/M era.
    Yes that's definitely a requirement. Single sided double density drives should be ok too since you can put a double sided disk in them and only read one side, correct?

  10. #40
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    I updated the Simple80 rev 1 design files with schematic, pc board design files, and software. It is a classical retro design with through-hole technology and 1980's components (except compact flash disk).
    https://www.retrobrewcomputers.org/d...smo:simple80r1
    It is a Z80 SBC with expansion and CPM capabilities where an inexpensive & proven kit is available. I like to keep the part cost down to $20. You can purchase the Simple80 IC kit on eBay for search for "simple80 z80", it is $6 plus $6 shipping. I have no business relationship with the seller, but have purchased several kits to check it out. You can get 5 pc boards made in JLCPCB for $2 plus $8-10 shipping.

    The CF interface is IDE44, so it should accommodate a spinning hard disk for true retro setup. I have not tested out the hard disk option on this particular design, but other designs use the same IDE44 interface have worked with hard disk.
    Bill
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