CP/M Z80 home brew computer circuit board bfranchuk at jetnet.ab.ca bfranchuk at jetnet.ab.ca <mailto:cctalk%40classiccmp.org?Subject=CP/M%20Z80%20home%20brew%20computer% 20circuit%20board&In-Reply-To=48546EA0.8000301%40pacbell.net> Sat Jun 14 21:08:23 CDT 2008 * Previous message: CP/M Z80 home brew computer circuit board * Next message: Fwd: Manual "IBM Card" Punch on eBay... * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ________________________________ Jim Battle wrote: Well when you think about it , I can down load a Z80 - CP/M emulator that is just as fast and I can read emulated disks from my PC. When I think CP/M I think floppy disk and I think you still can get the floppy disk controller chips. -----REPLY----- Hi! Thanks Jim for the comments. Please let me address the issues raised by Ben: If you look closely at the SBC design, you'll notice it has a feature even better than a floppy controller -- it has a fully buffered IO bus! It contains all the Z80 signals brought out to the DIN 41612 connector. The peripheral bus adheres to the published ECB standard. If you want floppy IO, the solution is simple -- just design one and attach it to the bus! I have already done this with my Disk IO board (IDE and NEC765 FDC) which plugs into my home brew ECB backplane along with the SBC. Assuming there is enough interest in these home brew SBCs, I hope to make a PCB version of the Disk IO board. Yes, this SBC is a slightly modern variation of a vintage Z80 CP/M design. I relaxed some of the traditions to make it affordable, reliable, and still useful. The P112, while an excellent design and a wonderful SBC, costs $165 for a kit when it is available. I know of no other hobbyist Z80 projects where one can purchase the PCB. There are many Z80 designs available, however, without a PCB it means most hobbyists will have to use temporary breadboards, wire wrap, or prototype boards. None of those lend themselves to long term reliable solutions -- especially for a wide range of hobbyist builders. The SBC PCB is meant to be *low cost* and the *common* element of a home brew computer with *simple* IO. Adding unnecessary and complex IO peripherals increases PCB area and cost, raises part count, and pushes away the hobbyists it is meant for. Selecting IO has to be done very carefully. Not everyone who builds this SBC wants floppy IO. I have had numerous requests for many forms of IO ranging from SCSI, IDE, floppy, CF, SD, USB, the Zilog peripherals, etc. There is no solution which will satisfy everyone. Implementing floppy IO can take on many variations and picking the FDC is just the first of many challenges [FDC1793? NEC765? SMC9266? WD2797?]. What about the data separator? Few chips remain and viable sources are scarce. Even integrated FDCs with built in data separators are not readily available. Please remember, this is a *home brew* computer project -- a *real* Z80 running CP/M 2.2 on *real* hardware. It is what you make of it. If all you want is a PC CP/M emulator then this project is not for you. Thanks and have a nice day! Andrew Lynch