As some of the regulars here will probably know, I am working on a project to develop a combination of Rombox and MLDL for the good old HP41. As development is now coming to a stage where there is some outlook to an actual prototype I would like to exchange information in a somewhat different way by starting a mailing list to keep all interested up to date with what's happening.
To subscribe to the mailing list please send an email to majordomo@kuipers.to with in the body the text: subscribe hp41_dev. To post a message simple send email to hp41_dev@kuipers.to. Note that only subscribers will be allowed to send messages to the list.
Let me know if you do not like this way of communication or if you rather prefer this forum.
The MLDL2000 is a non-profit project. All information will in the be available to the group under the GNU license: schematics, PCB layout, VHDL sources, specification, CPLD programming file. I will even use free tools as much as possible to accomplish all this. Most information is already available at www.kuipers.to/hp41.
Functionally, the MLDL2000 will store up to 47 (!) ROM images in Flash Eprom and up to 11 ROM images in SRAM, that can be edited at will with a suitable program. Bank switching will be supported and the MLDL2000 will have a simple interface to the outside world to allow up- and downloading of ROM images, programming and erasing Flash and to some extent data exchange with the HP41. For detailed specifications please have a look at www.kuipers.to/hp41
As I currently see it I will supply a PCB mounted with components and programmed CPLD. I will probably not supply the housing and/or the HP41 connectors. The PCB will be small enough to fit in a card reader housing. The CPLD with all the logic is reprogrammable in the field to add features or to fix bugs.
The project is far from finished, but proceeding nicely. No hardware is prototyped yet, but simulations show succesful access from Flash Eprom and SRAM, including the '040' WROM instruction. This leaves the external interface and bank switching to be implemented. I intend to start prototyping a simple rombox within a few weeks to prove interoperability with the HP41.
I would like to call for help for the following:
- PCB layout, prefreably in CADSOFT Eagle
- hardware design issues: 5V-3.3V conversion, supplies
- specifics on HP41 bank switching: need some more detailed info
If you think you have something to offer, please contact me!
As usual, comments are welcome!
Meindert