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from HC11 to 6809
DiTBho:
hi
every now and then I program in assembly for HC11, in particular I'm working on a VGA/PS/2keyboard terminal "similar" to the famous VT100&C but with a protocol rewritten from scratch to be as flexible and linear as possible.
However, I would like to redesign the mobo with an m68B09@2Mhz(2), as my protocol can have compression, and HC11 It's starting to make me think that it doesn't make sense to also implement this extension, while, by judging the datasheet, the 09 seems better promising!
Of course it would be even better to migrate to 68k, even better to forced 68020 with 8bit bus, I have an evaluation 68020@25Mhz board, and my terminal (C/89 code, recompiled from HC11 to m68k) runs like a rocket(1), the 020 is literally too fast for it, so I would like to stay at 8bit for the terminal, if anything uses the 020 to implement things which require more CPU power.
How tiring is it to migrate from HC11 to 09?
The various problems are:
gcc-3.4.6 is the latest to support HC11, and if you don't exaggerate, it generates decent machine code
G/AS from binutils supports HC11, but it doesn't support Motorola assembly
if Gcc is not enough I have the commercial icc/11 compiler, whereas for the 09 I don't have any commercial compiler, and I've never investigated the real status of the opensource support.
I know there is an experimental branch for Gcc/09, but his author wrote me it's still in beta-stage :-//
(1) gcc-v3.4.6 for HC11 seems to produce much less performant machine code than gcc v7.* for m68k, and I sometimes get the impression that gcc v4.1.2 produces even better machine code for 020! Anyway, for HC11 I already manually rewrote my software in assembly.
(2) Motorola made different speed grades of 6809:
6809@1.0MHz
68A09@1.5MHz
68B09@2.0MHz <----- my target
6809E, also, the datasheet reports a "/E" (suffix), which has no on-board oscillator and expects to receive an external clock.
DiTBho:
For those who have never read Wikipedia, here is the main article :D
pqass:
I've been looking for resources for 6809 too.
So far, I've found a cross assembler and ASSIST09 monitor but no C compiler yet.
It may be worthwhile to go with the 68008; same 8-bit width, slightly newer, faster probably same performance (both 8MHz xtals; รท4 vs 8-Tstates), cheaper than 68020, and better software support but only if you're porting C.
--- Quote ---... 6809E, also, the datasheet reports a "/E" (suffix), which has no on-board oscillator and expects to receive an external clock.
--- End quote ---
FYI: /E has new pins to support multi-cpu designs (pins 39,38,36,33) and Q,E are now inputs.
Also, a clock generator can be made with a 74HC74 dual D-FF (needs to be HC as output needs to be close to Vcc) fed from can oscillator 4x expected output (8MHz for 2MHz Q+E clocks).
bingo600:
--- Quote from: DiTBho on November 05, 2023, 04:11:34 pm ---6809E, also, the datasheet reports a "/E" (suffix), which has no on-board oscillator and expects to receive an external clock.
--- End quote ---
The MC6800/09 was the MCU's in my first PC :) :)
I loved that MCU
The E want's a dualphase clock
You could also look at the Hitachi HD6309 , a 09' with some extensions.
It might have better availabiiity.
I have only used Introl C for the 09' , on a TSC Flex system
A few resources i quickly found.
https://www.aslak.net/index.php/2018/03/07/exploring-c-compilers-for-the-6809/
https://sourceforge.net/projects/cmoc-win32/
But why a '09 ?
If you have C code you can port to the 68K , then it wouldn't be hard to port to an Arm.
Ie. a blackpill would give you 96K Ram , and lot's of processing power.
Are you using a 6845 or some other external "CRT Display Chip", needing the external/shared Ram ?
/Bingo
DiTBho:
--- Quote from: bingo600 on November 05, 2023, 05:01:39 pm ---If you have C code you can port to the 68K , then it wouldn't be hard to port to an Arm.
--- End quote ---
For 32bit stuff, I am already happy with my MIPS32 and MIPS2 boards.
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