Re: Todd's ELF-ish gets some more I/O #ELF #Homebrew


Hi Todd,

>> It's one of the reasons I put battery backup on all of the memory - so I don't have to reload the programs.

Note that a common bug when programming is a runaway stack, wherein the INC STACK and DEC STACK's aren't balanced.
This causes a stack crawl and may overwrite the program. Time to reload. I have an EEPROM to save stuff in.
The Elf and IDIOT's !M load routine is slow enough that the chip's byte write mode works just like RAM. I then
disable write with a jumper and block-move the code into RAM.

>> And it should not be hard to patch UT4 to use the UART.
 Since you have the UART, that's probably the easiest. But keep the Q/EF wiring in place as most 1802 software uses
bit-banged serial I/O.

 As for Monitors, most folks appear to be using UT4, IDIOT, Chuck Yakym's MCSMP, or ELF2K. The first 3 have similar
functions. ELF2K supports a disk operating system that can run on CF card "disks". MCSMP loads and saves I8hex files.
IDIOT and UT4 use RCA's !M format. MCSMP will run 9600 Baud at a CPU clock of 1.8 MHz. I use IDIOT, and an assembler that
creates RCA-compatible list files that IDIOT (or UT4) can load. IDIOT is run-time relocatable, and will find RAM to
save the registers. UT4 needs to be assembled with a RAM location coded in. UT4 supports JAM_8000 RUN_U, IDIOT does not.
 I am redesigning my Elf expander to locate IDIOT at F800, an EEPROM at 8000 or C000, and the rest RAM. RUN_U will use
the scheme in Ipso Facto.

 I like the labels on the underside of the chip sockets. How are these done??

>>  My design approach has been to use as many of the CDP1800 series as I could source
>> - and I managed to get just about the complete set.

Where did you get the 1863 frequency divider??
Please tell us more about the Logic Analyzer!


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