Search found 82 matches

by Tony Brewer
27 Apr 2018 23:47
Forum: NEW HARDWARE
Topic: Rodents anyone ?
Replies: 17
Views: 18289

Re: Rodents anyone ?

Dave, I was wondering whether the Propeller could replace the ATmega328.
by Tony Brewer
27 Apr 2018 18:07
Forum: NEW HARDWARE
Topic: Rodents anyone ?
Replies: 17
Views: 18289

Re: Rodents anyone ?

Could this be integrated with the keyboard interface, if it is meant to be more than just an experiment?
by Tony Brewer
27 Apr 2018 17:30
Forum: CP/M
Topic: Memotech CP/M System Sizes
Replies: 12
Views: 15451

Re: Memotech CP/M System Sizes

E988 is close to 59K, so perhaps this is where the system size comes from. The BIOS starts at E500, with BASIC system variables at the top of RAM.
by Tony Brewer
27 Apr 2018 17:21
Forum: CP/M
Topic: Memotech CP/M System Sizes
Replies: 12
Views: 15451

Re: Memotech CP/M System Sizes

The free space pointer (FSP) reported by config.com is D588 for the 54k system and E988 for the 59K system, 1400h (~5k dec) difference, but I am not sure what the FSP actually means? Is all of the memory between 100h and the FSP available for CP/M, but BIOS, BDOS, system variables, etc., above the ...
by Tony Brewer
16 Feb 2018 21:01
Forum: NEW HARDWARE
Topic: Keyboard replacement
Replies: 45
Views: 62893

Re: Keyboard replacement

Tony, The Propeller output cog does a "waitpne" on nine pins, not eight. The ninth pin is toggled by the keyboard decode cog whenever the state of the keyboard matrix changes. This causes the output cog to update the sense lines, even if the drive lines don't change. Bill. Thanks for the ...
by Tony Brewer
16 Feb 2018 20:26
Forum: NEW HARDWARE
Topic: Keyboard replacement
Replies: 45
Views: 62893

Re: Keyboard replacement

Hi Tony, your wish is my command :) The plan at the moment was to have USB and PS/2 connectors on the PCB (they should fit in the deepest past of the case OK). I realise that this would mean opening the case the plug in the keyboard, but if a jumper (or jumpers) are used, the case would need opened...
by Tony Brewer
16 Feb 2018 17:25
Forum: NEW HARDWARE
Topic: Keyboard replacement
Replies: 45
Views: 62893

Re: Keyboard replacement

Dave, How about adding the physical connection to your list of design goals? No need for any butchering of the MTX case in my opinion. Could you please post the photo of the StarTech USBMBADAPT cable here so others could see it? If the cable would be compressed when the lid is closed, then that woul...
by Tony Brewer
16 Feb 2018 15:44
Forum: NEW HARDWARE
Topic: Keyboard replacement
Replies: 45
Views: 62893

Re: Keyboard replacement

While on the subject of the ZX Spectrum and the MTX, how does Speculator handle the keyboard? Mark Mark, the Speculator uses the NMI to update part of the screen, read the border colour and write the Spectrum key values. /NMI goes low when /INT goes low, if enabled with an OUT FF bit. There is a 2K...
by Tony Brewer
16 Feb 2018 00:28
Forum: NEW HARDWARE
Topic: Keyboard replacement
Replies: 45
Views: 62893

Re: Keyboard replacement

Hello Dave, There would be wait states only on the MTXPlus+, not the MTX. The number of drive lines supported is a Propeller software issue. This project is a welcome short-term diversion for me. Further thoughts: 1. Add a 4-pin right-angle header to the back of the new PCB pointing backwards and co...
by Tony Brewer
15 Feb 2018 22:28
Forum: NEW HARDWARE
Topic: Keyboard replacement
Replies: 45
Views: 62893

Re: Keyboard replacement

Dave, I think it would take 1.5 us max to handle all eight drive lines. There is more than 2 us to play with on the MTX. Wait states would be required for most of the faster clocks on the MTXPlus+. In fact, the Prop could output /WAIT and there is a spare open-collector buffer available. Without dat...