In message <20040730013222.JQCO2991.orval.sprint.ca_at_smtp.sprint.ca>
Dave Dunfield <dave04a_at_dunfield.com> wrote:
> but.. especially in todays world (as you point out), having to get the "first"
> ROM programmed should not be a show stopper. Even that is only an issue if the
> OP decided to build my design "as is" - as discussed earlier in this message,
> a little flash device could be used and then all you need is a serial or parallel
> port to program it (depending on the requirements of the device). To me (primarily
> a software guy), using a little controller with lots of I/O and ability to time
> pulses far more accurately than winblows, it still makes sense to design a micro
> based device.
The other option if you need to make a bootstrap ROM and don't have access to
a programmer would be the "DIP switch and monostable" trick. A one-shot
monostable generates the program pulse, a bunch of DIP switches set the
address and data locations. A momentary pushbutton switch fires the
monostable, which gives the EPROM a 50mS program pulse, then waits for the
key to be released.
If I did something like that today, I'd probably use a few TIL311s, a 4040
counter and a bunch of switches. Or I'd use a PIC microcontroller and a
bit of assembler code to program the ROM.
Later.
--
Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem_at_dsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI
... My haystack had no needle!
Received on Fri Jul 30 2004 - 03:16:57 BST