Re: Noob question: examine arbitrary memory address? #ELF #memory


thinkpast
 

John Kennedy wrote:

Thanks all. I believe I have grok’d the way memory is laid out now. I’ve
made an EPROM with blinking Q code and can call it where I can expect it! Next
step is a monitor program. So far the serial loop back code works (all six
bytes!) but the IDIOT isn’t doing anything so I’ve plenty more to work on.
http://www.retrotechnology.com/memship/mship_test.html

has a bunch of 1802 MC test programs and little exercisers of the 1802 and one's progamming skills. The last program, is Lee Hart's attempt to write a front-panel monitor which only uses the front panel. So this answers the question of how to read arbitrary memory from a typical ELF front panel. One writes a program to read the toggle switches, does a thing, and display a result on the LEDs. How about, somebody finishes this program?

> but the IDIOT isn’t doing anything

Chances are the problem is that IDIOT is producing the wrong bits or reading the wrong bits. But there can be other problems, like baud rates. Read the fine Web pages:

http://www.retrotechnology.com/memship/mship_idiot.html
http://www.retrotechnology.com/memship/idiot_ramrom.html

A simple answer to how to operate Q and EF3 with IDIOT to match one's actual serial hardware, is to program a ROM with ALL FOUR WAYS, and then try each program. Put IDIOT in high memory and jump to each of four ways and see what happens. Kinda brute force but ROMS are much bigger than the 512 byte IDIOT monitor.

The simple test programs for EF3 and Q plus the Q LED display (in that first Web page I mentioned) can tell you (with a few tools and some head-scratching) what your external computer is expecting on its serial lines.

All these things, are ways one learns about these things and about the 1802. This is one reason ELF like microcomputers continue to be popular.

Regards, Herb Johnson

Join cosmacelf@groups.io to automatically receive all group messages.