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updates for Cyclone and AVR based CP/M implementations [message #10295] Thu, 30 March 2023 01:17 Go to next message
rhkoolstar is currently offline  rhkoolstar
Messages: 276
Registered: October 2015
Senior Member
Hi all
I updated my Cyclone variants, both Cyclone II and Cyclone IV to (finally) be able to use all interfaces in CP/M CP/M 3 You can now boot with any interface as active, giving you the option to use different baudrates (see rom file). Also the baudrate of serial interfaces can be set within CP/M. See the 'Whatsnew" file.
CPMega-88 has been updated with RTS handshake. (this also involved a PCB update) The major shortcoming of this board was that there was no way to use the (only) serial interface for file transfer. This is now fixed. A i8080 version of download.com (originally by Grant Searle) has been included and this works well.
I also changed the disk system. It now uses one similar to the Cyclone versions, i.e. 254 mountable volumes. Additional system tools are added: GETSYS, PUTSYS, FORMAT as well as an i8080 modified version of MOUNT.

All files are available on my builderpage
Have fun
Rienk

[Updated on: Thu, 30 March 2023 01:18]

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Re: updates for Cyclone and AVR based CP/M implementations [message #10314 is a reply to message #10295] Wed, 05 April 2023 00:17 Go to previous message
rhkoolstar is currently offline  rhkoolstar
Messages: 276
Registered: October 2015
Senior Member
I reworked the schematics. Freed up another io pin and added a busy LED for the SD card.
I reconsidered the level shifters for the serial port and instead applied them to the SD-card interface. Now the whole board is powered by +5v except the SD-card, meaning the AVR is now working within specs for the 20 MHz clock. The diode across the voltage regulator is for powering the board with the ISP interface, which connects to the SD-card slot. See attached schematics.
Any comments?
  • Attachment: CPMega88.pdf
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