ZXmore or the ZX80CORE follow-up
Posted: Sun Dec 28, 2014 7:11 pm
So - as announced previously there will be a ZX80CORE follow-up. It's got a new name ZXmore.
It is unfortunately not available at end of this year as planned but nearly finished and should be available from end of january (boards and kits).
First I planned only a few new features like some more memory and an eletronic bank switch for the ROMs but it got more and more and is not any more fixed on ZX80 or ZX81 but still compatible to these two computers.
But I wanted to have an additional support of Z80 computers and decided to realize a CP/M support as well. The main difference is that ZX80/81 has ROM at the bottom and RAM at the top while CP/M has it vice versa. So I needed a flexible memory layout and found a great solution which allows even to start a ZX spectrum 48k on it with restrictions like monochrome display and missing audio support. But I planned to realize an additional slot module for the extension connector to realize this later in 2015 to make the ZXmore to a full compatible 48k ZX Spectrum with color and audio.
It has also quite more memory (512k RAM and 512k ROM) divided into 8 images and can be switched either mechanical with the switch or electrical as well via software. So you have 64k RAM and ROM for every instance which can be diveded different for instance. This is a bit waste of memory (50%) but makes it more easy to realize technically. So later on I will provide an additional control image to change the default memory layout (ZX80/81 compatible) for use with CP/M and to control different additional features and start up to seven instances with different or maybe same configurations and task switching. Finally ZXmore will be able to offer a multitasking feature allowing to execute 2 or more instances at the same time while toggling the display / keyboard control with a simple key press.
So this will be a funny project which will accompany me and maybe you in the next year as it will have the ZX80CORE functionality in the beginning phase and allow the CP/M and multitasking options approx. in april next year through software/rom. In the summer the availability of the ZX Spectrum addon card is planned to turn the system into a full 48k ZX Spectrum with RGB/VGA output and audio.
I planned to finish the development in decembre this year but as you could imagine the whole feature list did require some time to finish. The main system is ready now with nearly all features but some changes are needed to put some logic into a (small) CPLD and to realize the USB interface to load and save data from an attached USB stick which offers additional functions for the CP/M (BDOS). I am now a bit unsure about a joystick support but maybe it is better to pack this on the Spectrum interface as this was not part of the original ZX81 development and there is no really joystick support other than simulating keypresses - different for many games. So maybe not as useful as somebody mind think first.
It is now my plan to have the boards and assembly kits in end of january. The form factor keeps the same as the ZX80CORE so it is still possible to put the whole board into the same acrylic case. There maybe a different layout at the backside which is not compatible to an original ZX80 case due to connector placements but whoever has theses cases at home ? The keyboard layouts can be individually changed to either the original high-glossy-ZX80 keyboard with or without smd tactile switches or with the ZX81 selfprinted layout together with the switches up to personal preferences. There will be also a hotkey feature to display the keyboard layout easily on screen with the control images which makes it easier to change or find the right key with the desired keyword. It is also planned to use additional the greater ZX spectrum keyboard together with the ZX Spectrum feature but maybe not many people are really programming on the ZXmore rather than starting some games on it.
Here is a feature list:
* ZX80, ZX81, CP/M compatible Z80 computer
* 512k ROM, 512k RAM divided into 8 images of 64k ROM and 64k RAM with variable ROM/RAM layout (4k steps), electronic switchable
* extended M1NOT feature with use of assembler(machine)code in the whole addressing space when using standard display (24x32 chars)
* HIRES compatible
* high speed mode (clock doubling) with 6.5 MHz instead of only 3.25 MHz
* integrated videodriver (ZX8CCB) and NMI module (ZX80NMIX)
* internal and external keyboard, open collector style as used for the ZX81
* USB interface to support USB stick
* multitasking feature
* ZX Spectrum 48k compatible with additional slot interface
The board/kits may not be much more expencive than the ZX80CORE but offer much more features.
Here some pictures from the prototype:
It is unfortunately not available at end of this year as planned but nearly finished and should be available from end of january (boards and kits).
First I planned only a few new features like some more memory and an eletronic bank switch for the ROMs but it got more and more and is not any more fixed on ZX80 or ZX81 but still compatible to these two computers.
But I wanted to have an additional support of Z80 computers and decided to realize a CP/M support as well. The main difference is that ZX80/81 has ROM at the bottom and RAM at the top while CP/M has it vice versa. So I needed a flexible memory layout and found a great solution which allows even to start a ZX spectrum 48k on it with restrictions like monochrome display and missing audio support. But I planned to realize an additional slot module for the extension connector to realize this later in 2015 to make the ZXmore to a full compatible 48k ZX Spectrum with color and audio.
It has also quite more memory (512k RAM and 512k ROM) divided into 8 images and can be switched either mechanical with the switch or electrical as well via software. So you have 64k RAM and ROM for every instance which can be diveded different for instance. This is a bit waste of memory (50%) but makes it more easy to realize technically. So later on I will provide an additional control image to change the default memory layout (ZX80/81 compatible) for use with CP/M and to control different additional features and start up to seven instances with different or maybe same configurations and task switching. Finally ZXmore will be able to offer a multitasking feature allowing to execute 2 or more instances at the same time while toggling the display / keyboard control with a simple key press.
So this will be a funny project which will accompany me and maybe you in the next year as it will have the ZX80CORE functionality in the beginning phase and allow the CP/M and multitasking options approx. in april next year through software/rom. In the summer the availability of the ZX Spectrum addon card is planned to turn the system into a full 48k ZX Spectrum with RGB/VGA output and audio.
I planned to finish the development in decembre this year but as you could imagine the whole feature list did require some time to finish. The main system is ready now with nearly all features but some changes are needed to put some logic into a (small) CPLD and to realize the USB interface to load and save data from an attached USB stick which offers additional functions for the CP/M (BDOS). I am now a bit unsure about a joystick support but maybe it is better to pack this on the Spectrum interface as this was not part of the original ZX81 development and there is no really joystick support other than simulating keypresses - different for many games. So maybe not as useful as somebody mind think first.
It is now my plan to have the boards and assembly kits in end of january. The form factor keeps the same as the ZX80CORE so it is still possible to put the whole board into the same acrylic case. There maybe a different layout at the backside which is not compatible to an original ZX80 case due to connector placements but whoever has theses cases at home ? The keyboard layouts can be individually changed to either the original high-glossy-ZX80 keyboard with or without smd tactile switches or with the ZX81 selfprinted layout together with the switches up to personal preferences. There will be also a hotkey feature to display the keyboard layout easily on screen with the control images which makes it easier to change or find the right key with the desired keyword. It is also planned to use additional the greater ZX spectrum keyboard together with the ZX Spectrum feature but maybe not many people are really programming on the ZXmore rather than starting some games on it.
Here is a feature list:
* ZX80, ZX81, CP/M compatible Z80 computer
* 512k ROM, 512k RAM divided into 8 images of 64k ROM and 64k RAM with variable ROM/RAM layout (4k steps), electronic switchable
* extended M1NOT feature with use of assembler(machine)code in the whole addressing space when using standard display (24x32 chars)
* HIRES compatible
* high speed mode (clock doubling) with 6.5 MHz instead of only 3.25 MHz
* integrated videodriver (ZX8CCB) and NMI module (ZX80NMIX)
* internal and external keyboard, open collector style as used for the ZX81
* USB interface to support USB stick
* multitasking feature
* ZX Spectrum 48k compatible with additional slot interface
The board/kits may not be much more expencive than the ZX80CORE but offer much more features.
Here some pictures from the prototype: