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Frequently Asked Questions


If you have a question that is not covered by the "Support" section of this site please don't hesitate to ask emailing to, don't forget mention CRISS in the Subject.

Is CRISS CP/M a retro computer?

No. It is NOT retro computer. It is modern computer specially designed so to be easy assembled at home and provides full functionality of the personal computer and support of standard peripheral devices: VGA monitors, PS/2 keyboards, printers.

But it runs standard CP/M OS because it has 8-bit architecture and this OS is the best choice for it. Due to that it is compatible with some CP/M platforms from 198x and can run its software that gives wide range of office, entertainment and business tools.

It can be used for many purposes: as a learning platform for kids to understand computer architecture and basic principles of programming, as a typewriter, as the control module for homebrew projects, as a spy-free computer to store and process your personal data. Really it is the safest computer in the world today!

What about CRISS CP/M localization?

CRISS by default is localized for English/US as the main layout and Russian as the secondary one. All system tools including the system console are in English language. But if you need any local alphabet and/or keyboard layout it is not a problem to replace it with your local requirements. Nothing special, just fill out some decoding tables. Firmware uploading procedure allows to replace it without full reprogramming.

The power input via HLK-5M05 should work on 120 V/60 Hz?

On the body it is mentioned then input voltage range is "100-260 VAC" so it should be supported.

In any case there is an optional DC input on the PCB that you can use with the external socket on the back panel. If you need this option please note it ordering the kit and AC/DC module will be replaced with the DC input socket and wire connector.

Ethernet, what exactly does it support? (I mean, DHCP, ping, telnet)?

For this firmware version it responds ARP and supports UDP transactions. LAN support is incorporated into the BIOS and you can use it via standard Puhch/Reader commands. IP/MAC for that case is pre-fixed via the system console (see image). Also it supports transparent mapping of input/output/printer BIOS functions to the LAN, you can use this feature for the remote control or monitoring, no coding required :) In future version some basic TCP support probably will be added. ICMP definitely no, telnet may be considered as an outgoing tool (just write it), remote control is already the basic option.

What is the EEPROM used for, how fast is it?

For now EEPROM is used to store 2 user sessions and quickly switch between them. Also the computer can be booted from the EEPROM - it can be used for the "embedded" applications, when no SD is on the board and CRISS is used to control external devices.

It is very fast: SPI bus 5MHz. You have direct access to it from the computer programs in just few lines of code.

UART/RS232 is that 3.5mm jack with TxD, RxD on the front panel?

CRISS CP/M has two serial interfaces: the system UART is the 3.5mm jack on the front panel and the MPS socket on the back panel that carries RS-232 signalling, external DB9 socket is assumed. Actually MPS plug holding 3 interfaces: keyboard, RS-232 and LPT via the special adapter, PCB for that is available. In the basic version MPS is a standard 6-pin minidin socket for the keyboard only. There are also some tricks how to use RS-232 in Standard version, if you need it just ask me.

I did not find a diagram of the PCB layout/part assembly, is it available?

Sure. By the request actual schematic, PCB layout and enclosure panels drawings will be sent. PCB layout please find at the the hackaday project page. Source codes are available on the Github.

What floppy images are supported?

Actually, CRISS CP/M supports floppies that are configured in the BIOS. In this version it is 819 kB images, compatible with Robotron PC 1715, two floppy drives are supported. After tuning number and format of disks can be changed if you really need it. SD-card may contain up to 32 floppy image that can be assigned to any drive from the system console but from the user program you are able to use up to 128 images, using "hidden" images for the data.

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