lowen
Veteran Member
Over 20 years ago a gifted engineer, Tilmann Reh, designed what some have considered the ultimate CP/M single-board computer, the CPU280. Now, that is a very subjective statement; some might say that the P112 with a CPU upgrade to 24.5MHz would be the 'Ultimate' and it's not the focus of this thread to argue about 'which is the ultimate.' Although David Brooks' P112 should be a reference design as well; you can learn a lot about designing stable crystal oscillator sections of a PCB from the P112 design! The focus of this thread is on a budding CPU280 revival, much like David Griffith's bringing back of the P112.
The CPU280 is based on the Zilog Z280 CPU at 12.288 MHz with up to 4MB of RAM on board, on-board floppy controller, two serial ports, boot-from-EPROM (a pair of them), and I/O through the common ECB bus. The Z280 is run in the 16-bit Z-BUS (Z8000-bus-and-peripheral-compatible) mode; thus an EVEN and an ODD EPROM.
Tilmann wrote in a comp.os.cpm post that only about 50 were ever built during the original run. The project was dropped once Zilog announced that production of the Z280 was stopping in early 1996. As early as TCJ issue #77 (available freely online), Tilmann had declared the board obsolete due to the difficulty of finding the parts, especially the Z280 CPU.
A few months ago, I became interested in the 'retrobrew' scene (the group formerly known as the 'N8VEM group') and begin investigating some of these SBC's, with an eye to porting the TRS-80 line's LS-DOS to what is ordinarily a CP/M-only board. (I'm porting LS-DOS 6 to the Lobo MAX-80, and to save wear-and-tear on the MAX-80 I'm learning the ropes of porting LS-DOS on newer hardware first).
I ordered two P112 kits from David Griffith and have built but not yet tested one of them. I've ordered a couple of bare boards for the retrobrew SBC-180 MkIV, and have even ordered an eZ80F91 development board from Mouser to play with. CP/M or a derivative such as ZSDOS is the native OS for these boards, of course, and the ideal OS for testing them prior to porting something else to them. There are other OSes, too, such as UZI-180, UZI-280, and Fuzix to play with.
I have corresponded with Tilmann over the last couple of weeks, and I have just ordered ten bare CPU280 boards from a PCB vendor. The Z280 CPU is more plentiful now than it had been (I have purchased 20 of them in the last four months), and the other chips are available if you look for a little while. So I am going to build up at least one CPU280 and will have a few bare boards left, I'm sure.
Tilmann has given me permission to share the English translations of the German manuals. Let me say that these are very well-written and describe the design in great detail. I've shared with the retrobrewcomputers.org group, since the CPU280 is both vintage and retrobrew (the design and first board run were in 1990, 26 years ago), and I encourage you to go there to obtain them (the zip file is too large for this forum's restrictions or I would upload here).
I'll let the forum know how the construction goes.....
If anyone here has or had a CPU280, I'd like to hear your story.
The CPU280 is based on the Zilog Z280 CPU at 12.288 MHz with up to 4MB of RAM on board, on-board floppy controller, two serial ports, boot-from-EPROM (a pair of them), and I/O through the common ECB bus. The Z280 is run in the 16-bit Z-BUS (Z8000-bus-and-peripheral-compatible) mode; thus an EVEN and an ODD EPROM.
Tilmann wrote in a comp.os.cpm post that only about 50 were ever built during the original run. The project was dropped once Zilog announced that production of the Z280 was stopping in early 1996. As early as TCJ issue #77 (available freely online), Tilmann had declared the board obsolete due to the difficulty of finding the parts, especially the Z280 CPU.
A few months ago, I became interested in the 'retrobrew' scene (the group formerly known as the 'N8VEM group') and begin investigating some of these SBC's, with an eye to porting the TRS-80 line's LS-DOS to what is ordinarily a CP/M-only board. (I'm porting LS-DOS 6 to the Lobo MAX-80, and to save wear-and-tear on the MAX-80 I'm learning the ropes of porting LS-DOS on newer hardware first).
I ordered two P112 kits from David Griffith and have built but not yet tested one of them. I've ordered a couple of bare boards for the retrobrew SBC-180 MkIV, and have even ordered an eZ80F91 development board from Mouser to play with. CP/M or a derivative such as ZSDOS is the native OS for these boards, of course, and the ideal OS for testing them prior to porting something else to them. There are other OSes, too, such as UZI-180, UZI-280, and Fuzix to play with.
I have corresponded with Tilmann over the last couple of weeks, and I have just ordered ten bare CPU280 boards from a PCB vendor. The Z280 CPU is more plentiful now than it had been (I have purchased 20 of them in the last four months), and the other chips are available if you look for a little while. So I am going to build up at least one CPU280 and will have a few bare boards left, I'm sure.
Tilmann has given me permission to share the English translations of the German manuals. Let me say that these are very well-written and describe the design in great detail. I've shared with the retrobrewcomputers.org group, since the CPU280 is both vintage and retrobrew (the design and first board run were in 1990, 26 years ago), and I encourage you to go there to obtain them (the zip file is too large for this forum's restrictions or I would upload here).
I'll let the forum know how the construction goes.....
If anyone here has or had a CPU280, I'd like to hear your story.
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