NP-41 Emulator (may be)

[jch]

(01-28-2016 06:55 PM)Chris Chung Wrote:  After looking into the peripheral and ROM extensions in more detail, I can see the current hardware is not adequate to support them.

Are you thinking of GPIO / SPI / UART / ... ?

(01-28-2016 06:55 PM)Chris Chung Wrote:  Anyway, my objective for this design has not change. It should stay being simple and easy to build. Altering the design will take more time than I like, as I need to know the stuffs (ROM / HP-IL, etc) in order to implement them.

Yes, this project is so exciting. I can't wait :-)

(01-28-2016 06:55 PM)Chris Chung Wrote:  I would still like to make provisions for expansion based on the somewhat limited hardware resource. Running ROM instructions from external chips via SPI / I2C will be way slow.

Or not... If the access time of external devices is low compared to the microinstructions emulation time ?

(01-28-2016 06:55 PM)Chris Chung Wrote:  So the most I can do is try to use the spare flash memory on the MSP430G2955. I would think there will be always 10k left, enough for a 2 x 4K ROM module.

I am planning to add an micro SD/MMC card reader to the unit w/ a read-only small footprint FAT file system. I can place ROM files in a SD card (up to 2G), and via software setup, I can "load" particular ROM from the FAT FS to a flash partition in the MCU. The loading will take a few seconds and have the effect of inserting a ROM pack into slot 1. And the unit will have only 1 slot, as restricted by the available flash memory.

My question is, will this be useful in many / most cases? As the ROM module space is limited to 2 x 4K.

I'm affraid that even the small footprint FAT file system will take some precious Flash and RAM ressources.
Perhaps a mix with USB transfer, on board fast serial flash and SD Card ?

Jean-Christophe.