6809 Single Board Computer project - Page 1
Forum section: electronics / projects

author: ron.owens
author_rank: Regular Contributor
timestamp: May 30, 2016, 03:26:14 pm
content: I've been working on a 6809 Single Board Computer design and I wanted to share it with the community. I've attached the schematic as a pdf. I would be interested in hearing from anyone interested is helping out, or just has an opinion to share. I think I've gotten it right, but that usually means there are a couple of nasty bugs I'm overlooking.This design includes a Memory Management Unit (MMU) so the CPU has an address space of 8MB. Although it's not a flat linear memory map, it's a lot to work with. There will definitely be software required to manage the MMU. I was hoping that this board will be able to run OS/9. I'm sure that will require some modifications to the OS to handle the MMU.Also there is a USB interface so a flash memory stick can be used for mass storage. This will also require modifications to the OS, if OS/9 is used. There is some interesting I/O on board - a stereo sound generator circuit and an Arithmetic Processing Unit (APU), along with two serial ports and two parallel ports. There is an expansion bus so more stuff can be added later. I've also added the USB File Manager module schematic. I'll post more on this later.I'm primarily a hardware guy. I'm looking for a software person to help with a ROM monitor and work on the OS, If you think that is something you would like to try, please post.Best regards,Ron

author: PuterGeek
author_rank: Regular Contributor
timestamp: May 30, 2016, 08:49:42 pm
content: OS/9 and 6809! Now that triggered a flashback from college! Great chip and OS for the time!You shouldn't have a problem if you used the Motorola MMU. If memory serves me it was supported by at least some versions of OS/9.But I think you posted the wrong schematic...

author: PuterGeek
author_rank: Regular Contributor
timestamp: May 30, 2016, 09:43:07 pm
content: Wow! Made me go Google some 6809 history!Did you find stock of a 6809 somewhere?Are you using the 6829 MMU and where did you find one?I taught a class to Georgia Tech grad students on the 6829 probably about 1982. It was the first exposure most of us had to a MMU.

author: ron.owens
author_rank: Regular Contributor
timestamp: May 31, 2016, 03:13:16 am
content: I used a SN74LS610 MMU from Texas Instruments. MC6829's are virtually nonexistent. I don't think they were ever manufactured in quantity. I searched for the part a lot and came up empty handed, I wish I could have gotten them, the 6829 is a better part than the 74LS610. But I used what I could get. I was thinking, since the 74LS610 and the MC6809 chips are very available on eBay, at least my design could be built by a few people. It doesn't seem fair to post a circuit that can't be built.I'm currently routing the PCB and should be finished with it soon. I see that the main schematic didn't post. I'll include it here. The other schematic is the USB interface.

author: PuterGeek
author_rank: Regular Contributor
timestamp: May 31, 2016, 07:54:12 pm
content: Nicely done with an interesting mix of old and new!I like seeing an old favorite get some love but an unusual choice. Why the 6809?

author: ron.owens
author_rank: Regular Contributor
timestamp: May 31, 2016, 08:01:53 pm
content: Once upon a time, in a career long ago, I worked at Motorola in the late 70's. Never got around to building a 6809 board. A Radio Shack CO-Co was as close as I got.Besides, it's one of the best 8-bitters ever made.

author: Fungus
author_rank: Super Contributor
timestamp: May 31, 2016, 08:11:02 pm
content: Quote from: ron.owens on May 31, 2016, 08:01:53 pmDefinitely better than Z80 and 6502.I'm surprised it wasn't more popular, unless "price".

author: PuterGeek
author_rank: Regular Contributor
timestamp: May 31, 2016, 08:23:12 pm
content: Quote from: ron.owens on May 31, 2016, 08:01:53 pmI have to agree on that point! And it was one of the last of the separate processors.The microprocessor professor at Georgia Tech, Dr. John Peatman, was a big Motorola supporter. Probably helped that Motorola donated to the college. Dr. Peatman worked at HP during the summer so we had a lab full of HP development systems tied together on a IEEE-488 'network'.One of the fun projects I did was create a 6809 structured assembler for the development system. HP had a universal assembler tool that managed all the common tasks (symbol recognition, hash table, etc.) so all I had to do was handle the stuff unique to the structured assembler.And in case you're wondering, a structured assembler has macro like instructions for common programming structures such as IF THEN ELSE and DO WHILE. A step short of a C compiler (which we didn't have) but made coding a little cleaner.The programming we did was mostly BASIC09 and a little assembly. I don't think we had a native assembler and BASIC09 ran under OS/9.BASIC09 compiled into "p-code" which was interpreted at runtime. Made for fairly compact code and reasonable execution speed.Thanks for the prompt for a trip down memory lane! Good times when I was just getting started!

author: PuterGeek
author_rank: Regular Contributor
timestamp: May 31, 2016, 08:36:53 pm
content: Quote from: Fungus on May 31, 2016, 08:11:02 pmI think it was mainly because of Motorola's lack of focus. They were more diversified company (radios thru all sorts of semiconductors) while MOS Technologies, Zilog and Intel were mostly microprocessor companies.Much like the Z80 was an improved 8080, the 6502 was an improved 6800. The 6809 is largely an improved 6502, adopting the 6502 improvements and adding more on top.But it was the end of the 8-bit standalone era. Motorola came out with the 68000 (in the giant 64 pin DIP) and Intel brought out the 8086. Motorola moved the 8-bitters to microcontrollers like the 6801 and later the 68HC11.

author: NEALC
author_rank: Newbie
timestamp: August 20, 2016, 06:05:41 pm
content: Hi Ron,how is your board design coming along? I have done some work with an fpga-based 6809 system and ported a bunch of pre-existing software, some of which might be of interest to you:"buggy" a debug monitor with line assembler/disassembler"FLEX" the swtp OS"NitrOS9" a open source OS9 rewrite"FUZIX" an open-source unix for small systemsDetails on all of these on githubhttps://github.com/nealcrook/multicomp6809RegardsNeal

author: bingo600
author_rank: Super Contributor
timestamp: August 20, 2016, 07:01:51 pm
content: OhhBrings back memories of my old Flex system , my first computer.I even have that fpga board , and some ram ...... hmmm ...../Bingo

author: Pjotr
author_rank: Frequent Contributor
timestamp: August 20, 2016, 07:46:20 pm
content: 6809... Brings back memories. Build many precision servo controllers with it and even a sophisticated sequencer for controlling a Moog analogue music synthesizer those day's. But better than a Z80? Depends on the state of the moon at your birth IMHOReal programming those days was assembly coding. The 6809 stood out the rest by its neat and extensive instruction set that was a pleasure to use. There was even a kind of instruction that acted as kind of a pointer to a pointer. Very handy for lookup tables. Must have still somewhere a floppy with an assembler that ran on a Atari1040.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 20, 2016, 10:25:28 pm
content: Funny, I recently came into some old chips, including 6809s (but none of the aforementioned MMU parts, oh well). List:http://seventransistorlabs.com/Images/Chip_Inventory.txtTim

author: coppice
author_rank: Super Contributor
timestamp: August 21, 2016, 04:26:01 am
content: Quote from: Fungus on May 31, 2016, 08:11:02 pmPrice favoured the MC6809, as it was a small chip, but it was a little too late. 16 bit devices were already getting traction, and the 8088 was available for people needing a low pin count device with an 8 bit external bus. If the MC68008 had been part of the initial launch of the 68k, rather than an afterthought, the 68k family might have been a lot more successful.

author: ron.owens
author_rank: Regular Contributor
timestamp: August 21, 2016, 08:35:21 am
content: The aforementioned MMU parts, 6829, were never manufactured. Motorola only produced 'engineering' samples'. It's too bad because that is actually a very cool part. I have heard of it being implemented in a FPGA and works quite well. My weapon of choice for MMU is the 75LS610. It works fairly well in 6809 and Z80 designs, but was originally designed by Texas Instruments to work with the TMS9900, a 16-bit processor. As such, it requires a few logic tricks to get it to play nice with 8-bitters. However, if successfully implemented it can allow 20-bit addressing. I would think if someone was going to go to trouble of designing a 6829 MMU in a FPGA, they might as well make a 6809 with a 24-bit address bus and register support to make it work. Now that would be a very cool part.

author: Pjotr
author_rank: Frequent Contributor
timestamp: August 21, 2016, 09:06:56 am
content: An 8-bitter with 24 bit address bus (or MMU)? What are you up to? Apart from embedded control those 8-bitters were used for administration tasks for a while (under CPM etc.). Only for the latter a MMU was profitable to handle larger chunks of data. Most embedded control tasks didn't need it. I think more than emulate original parts and running software of those days has no use.

author: ron.owens
author_rank: Regular Contributor
timestamp: August 21, 2016, 09:22:04 am
content: You are absolutely right, it's of no use. It's based on vintage CPUs and inherently has no use by obsolescence. Most people designing and building vintage computers do it for enjoyment. Much the same way someone restores an old automobile when a much improved version can be purchased from a dealership. I imagine very few people build 8-bit computers with microprocessor from the 1970's and 1980's to make money.I recently watched a video of a guy building a fully functional artificial hand from a brand new coffee maker. And I thought I had too much time on my hands! I think he did it because he could. Given his talent, I would think he could make a fantastic hand from more standard parts. I think hobbies are seldom done because of their 'use'. But that's just my opinion.

author: bingo600
author_rank: Super Contributor
timestamp: August 21, 2016, 01:07:48 pm
content: Nice infohttp://www.baltissen.org/newhtm/74ls612.htmhttp://www.6502.org/users/andre/icapos/mmu65.html/Bingo

author: woodchips
author_rank: Frequent Contributor
timestamp: August 22, 2016, 05:55:06 pm
content: Nice, I like the 6809.Another rare, or invisible, chip was the 6840 floppy controller. Did anyone ever get one?

author: edavid
author_rank: Super Contributor
timestamp: August 22, 2016, 07:03:04 pm
content: Quote from: woodchips on August 22, 2016, 05:55:06 pmThe floppy controller was the MC6843. It was not very popular, but it was definitely produced (I have at least one). The MC6840 was a triple timer.

author: xygor
author_rank: Regular Contributor
timestamp: August 22, 2016, 07:33:26 pm
content: The Coco 3 used the TI MMU and ran OS/9. That might make a good starting point. The memory limit may be hard-coded into OS/9 in such a way that will make if difficult to increase. Also applications such as BASIC and the assembler might have to be modified. Or maybe not.

author: edavid
author_rank: Super Contributor
timestamp: August 22, 2016, 07:48:43 pm
content: Quote from: xygor on August 22, 2016, 07:33:26 pmIt did not use a TI MMU - the MMU was in the "GIME" ASIC.

author: xygor
author_rank: Regular Contributor
timestamp: August 22, 2016, 07:52:51 pm
content: Quote from: edavid on August 22, 2016, 07:48:43 pmWho made the ASIC?

author: edavid
author_rank: Super Contributor
timestamp: August 22, 2016, 08:46:18 pm
content: Quote from: xygor on August 22, 2016, 07:52:51 pmI think VLSI.

author: ron.owens
author_rank: Regular Contributor
timestamp: August 23, 2016, 01:45:35 am
content: Good luck getting any useful information on the GIME. It's even harder to get a chip, unless you dissect a CoCo III. In that case, you might as well use the CoCo III! It was very specific to that design.

author: coppice
author_rank: Super Contributor
timestamp: August 23, 2016, 01:47:47 am
content: Quote from: edavid on August 22, 2016, 07:03:04 pmI also used the MC6843. I implemented my own driver so that it emulated the discrete floppy controller card in the original MC6800 development systems, and allowed the Motorola development tools to be run on a wider range of hardware.

author: ron.owens
author_rank: Regular Contributor
timestamp: August 23, 2016, 01:58:33 am
content: Quote from: coppice on August 23, 2016, 01:47:47 amI didn't even know the 6843 existed until I saw it posted here. And I actually worked at Motorola back in the day! By the way... they are going for $40US on eBay.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: August 23, 2016, 02:23:46 am
content: Wow. Good on ya for resurrecting the venerable 6809. I used one in a couple similar projects in 1981-84 to develop a specialized computer for a film processing lab. With two stack pointers and a very symmetric and concise instruction set, around where I worked it was acknowledged as the most elegant 8-bit machine there was. Imagine having not just one but TWObranch neverinstructions, a short branch never (2 machine cycles) and a long branch never (3 instructions) as well as the usual bunch of other branch instructions. But with the ability for position-independent or re-entrant code (think Towers of Hanoi), anything was possible.Too bad it was so slow or else it could have done some real damage in the early PC market.

author: NEALC
author_rank: Newbie
timestamp: August 23, 2016, 06:25:50 pm
content: ...However, the mmu capability of the gime *is* well documented and my github repository has a functional equivalent coded in vhdl.Neal

author: ron.owens
author_rank: Regular Contributor
timestamp: August 23, 2016, 08:48:08 pm
content: Quote from: NEALC on August 23, 2016, 06:25:50 pmThat is very cool. Do you have a link? I really wish I could get a FPGA in through-hole, but I would settle for a surface mount part to get a great MMU.

author: NEALC
author_rank: Newbie
timestamp: August 24, 2016, 07:22:11 pm
content: https://github.com/nealcrook/multicomp6809/blob/master/multicomp/Components/MMAPPER2/mem_mapper2.vhdNote that this code is not register compatible with the gime mmu, but is (afaik) functionally compatible.Neal

author: bingo600
author_rank: Super Contributor
timestamp: August 24, 2016, 07:41:14 pm
content: Quote from: NEALC on August 24, 2016, 07:22:11 pmJust tried if it would fit one of the cheap EPM240 boards , and it's a tight fit but doeshttp://www.ebay.com/itm/1PCS-NEW-EPM240-Altera-MAX-II-CPLD-Development-Board-/272086159418Code:Fitter StatusSuccessful - Wed Aug 24 21:32:55 2016Quartus II 64-Bit Version13.0.1 Build 232 06/12/2013 SP 1 SJ Web EditionRevision Namemem_mapper2Top-level Entity Namemem_mapper2FamilyMAX IIDeviceEPM240T100C4Timing ModelsFinalTotal logic elements235 / 240 ( 98 % )Total pins43 / 80 ( 54 % )Total virtual pins0UFM blocks0 / 1 ( 0 % )/BingoEdit: Note a MaxII EPM240 is NOT 5v tolerant

author: ale500
author_rank: Frequent Contributor
timestamp: August 30, 2016, 05:03:19 am
content: Cool project !!!, I'd have used a couple CPLDs instead of GALs, just because I have no GAL programmer.A while ago, I got a MC6847 and a 74LS783 to recreate a CoCo1, I also picked up a MC68B09E, still on the drawing board...

author: obiwanjacobi
author_rank: Super Contributor
timestamp: August 30, 2016, 08:48:52 am
content: Quote from: bingo600 on August 24, 2016, 07:41:14 pmIt can be done (8-3):https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/hb/max2/max2_mii51009.pdf

author: bingo600
author_rank: Super Contributor
timestamp: September 04, 2016, 04:36:15 pm
content: Yesss - My retro 6809 is alive.Thanx Neil , for selling me a PCB.And answer my kazillion questions on startup.Code:6809 CamelForth v1.1 20 Mar 16OK HEXOK 1000 1FFF PASSOK HEXOK 1000 1FFF 10 PASSES ................OK HEXOK 0800 CFFF 10 PASSES ................OKI got the PCB assembled , but uses serial as console instead of VGA/KBD.Got the 512K Ram going , and thats what is tested in above listing.Now to connect the SD adapter & make a SD card/Bingo

author: bingo600
author_rank: Super Contributor
timestamp: September 04, 2016, 09:05:48 pm
content: And it's booting FLEXQuoteI feel like 20 again/Bingo

author: ale500
author_rank: Frequent Contributor
timestamp: September 07, 2016, 02:58:40 pm
content: QuoteCan you elaborate ? In which regard is the'09 an improved 6502 instead of an improved 6800 ?

author: Fungus
author_rank: Super Contributor
timestamp: September 07, 2016, 05:16:25 pm
content: Quote from: ale500 on September 07, 2016, 02:58:40 pmNah, they're totally different beasts.The only real similarity is they both start with a '6' and have four digits in their name. Apart from that? Nada.(...and they both come in 40-pin DIP packages)

author: bingo600
author_rank: Super Contributor
timestamp: September 07, 2016, 05:59:24 pm
content: The 6502 was designed by former Motorola designers , and some of the 6502 instructions could be considered an improvememt over the 6800.If you can program a 6800 in assembler you won't have many problems , switching to a 6502.A bit like the 8080 vs Z80 , although the 6502 isn't opcode compatible with the 6800..The 6809 ... Well simply the "best" 8 bit instruction set ever invented , but as a CISC some of the opcodes takes a lot of cycles.The 6309 even added more features to the MCU , while maintaining backwards compatibility./Bingo

author: woodchips
author_rank: Frequent Contributor
timestamp: September 07, 2016, 07:33:58 pm
content: Ah, yes, you are correct, the floppy controller was the 6843, how silly.The 6502/6800? Different instructions, but better? An overflow flag is a wonderous thing, but a PUSHX and PULX instruction really would have been useful.

author: Fungus
author_rank: Super Contributor
timestamp: September 08, 2016, 06:02:38 am
content: Quote from: bingo600 on September 07, 2016, 05:59:24 pmAll the addressing modes, etc., are completely different.Two accumulators, 16-bit addressing registers (LEA instructions), two stacks...A 6502 would feelreallyrestricted after using a 6809.You could switch over, sure, but I don't think knowing 6809 would give you any special advantages over knowing any other assembly language of the era.

author: legacy
author_rank: Super Contributor
timestamp: October 22, 2016, 05:53:05 pm
content: interesting topicany news?

author: vladk
author_rank: Newbie
timestamp: October 27, 2016, 03:05:02 am
content: Quote from: ron.owens on May 31, 2016, 03:13:16 amCould you please share here the contents of GALs used in the MC6809 project?For example, how exactly do you form the "Write STROBE" signal for the 74LS610 MMU ?Regards,Vladislav

author: bingo600
author_rank: Super Contributor
timestamp: October 27, 2016, 02:21:46 pm
content: Quote from: Fungus on September 08, 2016, 06:02:38 amI never compared the 09' to a 6502 , i wrote 6800/Bingo

author: NEALC
author_rank: Newbie
timestamp: November 17, 2016, 08:32:25 pm
content: Quote from: rainsee on November 17, 2016, 09:34:45 amHuh? that's what I wrote in Reply #9 on: August 21, 2016. Are you a spambot?

author: David Hess
author_rank: Super Contributor
timestamp: November 18, 2016, 07:23:38 am
content: Quote from: PuterGeek on May 31, 2016, 08:36:53 pmThis was my experience at the time when evaluating the 68HC11 via the 68HC811 and 64HC24 port replacement unit. Availability was so poor that we abandoned and anything from Motorola which was not second sourced. As someone mentioned, the 68008 should have been available with the 68000 but Motorola just did not seem interested in having IBM as a customer.Quote from: Pjotr on August 20, 2016, 07:46:20 pmDouble indirect addressing proved to be a real millstone around the neck of the 68000 microarchetecture when superscalar operation and pipelining were implemented. Linus even uses it as an example of not thinking ahead.

author: coppice
author_rank: Super Contributor
timestamp: November 18, 2016, 08:03:33 am
content: Quote from: David Hess on November 18, 2016, 07:23:38 amWas that around 1994, when Motorola was cracking up from its own success? They did so well with design ins for HC11 and HC05 devices in the previous couple of years that they lacked the production capacity to service those customers when it came to mass production. The repercussions of that made many designers stay away from Motorola parts for a long time.

author: David Hess
author_rank: Super Contributor
timestamp: November 18, 2016, 06:59:16 pm
content: Quote from: coppice on November 18, 2016, 08:03:33 amIt was around 1994 but it was a continuing problem for years before and after and I did get the idea that they had some major customers on allocation. The result was dropping 68HC11 for PIC which while not completely satisfactory was at least available.I finally received the 64HC24s that I needed months later and I still have them somewhere.

author: coppice
author_rank: Super Contributor
timestamp: May 31, 2017, 01:20:03 pm
content: Quote from: coppice on August 23, 2016, 01:47:47 amWhile sorting through some old papers today I came across the schematic I produced for that MC6843 based floppy disc controller in about 1978 or 79. A very nostalgic moment.The circuit has an NE564 PLL, and some counters and flip-flops to recover the clock from the disc data. It also uses a whole 8 bit port of an MC6821 parallel port interface for drive select, side select, door lock, and so on. Later floppy disc controller chips were more complete than that.

author: jbeeksma
author_rank: Newbie
timestamp: August 20, 2017, 11:31:20 am
content: Hi Ron,In 1976 me and some frined started building our own Motorola 6800-based computer. Some later, we built a Mark II based on the 6809. It is the best microprocessor for assembly programming EVER!We built the 'OS' ourselves, and reverse engineered an assembler and editor and a BASIC interpreter from hex dumps. Those were the days.I've been looking for a single-board 6809 based microcomputer to relive the old days, and would love to work with you on the software, if you're still looking for help in that department.Just drop me a line if you're interested.

author: jbeeksma
author_rank: Newbie
timestamp: August 20, 2017, 11:35:24 am
content: Hi Ron,The schematic in your post just contains a small part of the project. Is the full schematic avaiable somewhere? Did you produce PCB's, and are these available?I'd love to build one!Best regards,Jacob

author: digsys
author_rank: Unknown
timestamp: August 20, 2017, 12:59:10 pm
content: Add one more for the - ahhhhhh wonderful memories !! And I agree with many on this thread, one of the best (or the best) 8bitters of it's time.Just checked, still have some 6809s and peripheral chips. Had the $12,000? emulator for it, and many other expensive development tools.Gave the whole lot away (to someone on this forum) a few years ago, including 100s of original data books. Made many industrial controllers using the 6809.I do remember the last (short lived) generation of TRS80s (?) switched to 6809 (from Z80 I think). I got straight onto dis-assembling the source code :-)I even worked on a 1st (short lived as well) version of an IBM compatible - before the NEC APC3 mess. Yep, old memories.Maybe even have all my old circuits / pcbs layouts somewhere, but I think they are bishop graphics tapes on vellum !!!

author: grantb5
author_rank: Regular Contributor
timestamp: September 06, 2018, 03:13:28 pm
content: Not sure it would be helpful, but I have a 6809 ROM monitor somewhere around here that I wrote long ago. I think I used the PTM on the NMI pin for single-stepping. It's just a basic monitor but it's (text) menu driven and has breakpoints as well (for code in ram). I ported it to the 68HC11 ( yes such a big step down CPU-wise) and then later to the Hitachi 6303 for a synthesizer I'm working on (yet another step down ... I think I'm at the 6502 level by now). Anyway it looks more or less like this and hopefully I can dig it up. Not sure what assembler I used.http://musictechnologiesgroup.com/blog/?p=293

author: intabits
author_rank: Frequent Contributor
timestamp: September 10, 2018, 05:53:33 am
content: I only became aware of this thread when the recent post brought it into view, where the phrase "6809 Single Board Computer" caught my eye.Some time in the 1980's (judging by the latest date code, about 1985) I bought and assembled this "Uniboard" by "Compacta Incorporated". They supplied just the PCB and a couple of pre-programmed PALs, and the user had to source all the other parts and assemble it.It's been sitting in my junk room since then, and I'm struggling to remember if I even ever got it going. I think I did, but I can't picture it actually running, so maybe not. I do remember that U15, the ceramic chip with the badly corroded lid, an MC6844 DMA controller, was hard to get and expensive. The board has some corrosion and general scum, but it does look a little worse in the photo than it actually is.I don't know where the documentation for this is, I think I've lost it. It was only a few sheets of paper, not a proper manual. A few months ago, I tried searching online for some documentation, but couldn't find anything about it.Does this thing jog anybody's memory? Any clues as to where to find some doco on it?I'd like to make a video about it, but that would be pretty dry unless I could also show it operating, and the docs would be a big help for that.In the meantime, I'd better try to copy those ROMs and PALs...

author: grantb5
author_rank: Regular Contributor
timestamp: September 10, 2018, 01:15:49 pm
content: You may need to get more eyes on this in order to turn up something. Reddit has a 6809 subreddit and a retrobattlestations reddit, though hard to say who visits those. Maybe the Vintage Computing or Vintage CPU forums would be better. I don't have links for those last two handy.https://www.reddit.com/r/6809/https://www.reddit.com/r/retrobattlestations/

author: intabits
author_rank: Frequent Contributor
timestamp: September 11, 2018, 05:38:19 am
content: Thanks for those suggestions, I will try places like that.

author: grantb5
author_rank: Regular Contributor
timestamp: September 11, 2018, 01:15:46 pm
content: That's a really interesting board. Huge effort one someone's part. Do you have an EPROM programmer than can archive that old ROM? Looks like maybe a EPROM-microcontroller below that too. Can't see what that is. Bunnie Huang m(sp?) ight be interested in thishttps://www.bunniestudios.com/blog/.Anyway, it is mentioned here:http://www.vcfed.org/forum/archive/index.php/t-54578.html

author: grantb5
author_rank: Regular Contributor
timestamp: September 11, 2018, 01:19:50 pm
content: There is an ad for it here. Maybe they did an article for it at one point in 68 Micro Journalhttps://ia800605.us.archive.org/35/items/68micro-vol-07-num-04/V07N04_Apr1985.pdfIt's also briefly mentioned in an article here:https://ia800709.us.archive.org/10/items/the-computer-journal-63/tcj_63_September-October_1993.pdf

author: intabits
author_rank: Frequent Contributor
timestamp: September 11, 2018, 03:20:51 pm
content: Thanks for the links.Quote from: grantb5 on September 11, 2018, 01:15:46 pmNothing like that on it. If you mean U23 (above U14), its an FD1797 floppy disk controller.I managed to read the monitor ROM (U14, a 2732), and the video character generator ROM (U59, a 2716).But the two PALs (U29 PAL12L60J) and U40 (PAL10L8CN), both from MMI are unknown to my programmer. Looks like a job for Arduino...(update: U29 might be a PAL12L6CN)The only ASCII in the ROM is a few error messages:-

author: grantb5
author_rank: Regular Contributor
timestamp: September 11, 2018, 03:32:41 pm
content: Sorry, I meant U15.Excellent work so far. That's a great photo too.

author: grantb5
author_rank: Regular Contributor
timestamp: September 13, 2018, 11:10:00 pm
content: Quote from: grantb5 on September 06, 2018, 03:13:28 pmI found some of my stuff."6809 & 68HC11 Monitors, Assemblers, C Compilers, RTOS … from the 90s"http://musictechnologiesgroup.com/HC11/By the way, the ASxxxx Baldwin Assemblers are still supported and you can download then from (including source):http://shop-pdp.net/ashtml/asxxxx.htm

author: digsys
author_rank: Unknown
timestamp: September 14, 2018, 02:51:53 am
content: The 6809 was one of my favorite processors, I even made severa "industrial" motherboards for it. Unfortunately, I threw out 100s of PCBs a couple years ago,at a local hamfest. Even all the emulators and dev tools :-( Still have heaps of peripheral chips for it, but they too will go at the next purge .. siigh

author: tkamiya
author_rank: Super Contributor
timestamp: September 14, 2018, 03:21:05 am
content: Wow....Brings back (found) memories! 6809 was my favorite CPU when it was called a "newly introduced CPU" and "the latest". What I did was rather small scale. I've designed an industrial single board and used it to read XYZ signal from a HUGE digitizing machine. Then spit out the coordinate to a paper puncher. Only thing was, the speed of which the signal came out was faster than any cpu can catch, so we/I wrote to a memory space physically via DMA and then flipped that memory space to control under cpu to read.Ported a simple monitor program (firmware) and trig functions. Fun stuff.I liked 6809 over 8080 or Z80 for its simplicity. Compared to it, intel/zilog series were cumbersome. I understand 6809 was a reimagined PDP11 where as 8080 was a supersized calculator?It was so long ago at near beginning of my carrier. I don't remember much.

author: grantb5
author_rank: Regular Contributor
timestamp: September 14, 2018, 03:41:12 am
content: Byte MagazineA MICROPROCESSOR FOR THE REVOLUTION: THE 6809Volume 04 Number 01https://cdn.hackaday.io/files/460001968064000/byte_6809_articlesx3.pdf

author: innkeeper
author_rank: Unknown
timestamp: September 14, 2018, 05:41:43 am
content: trs-80 color computer ... did a lotta programming and hardware hacking on that back in the day.also did some custom com boards using the 6809.. love that processor.

author: coppice
author_rank: Super Contributor
timestamp: September 14, 2018, 09:07:34 am
content: Quote from: tkamiya on September 14, 2018, 03:21:05 amIts unreasonable to compare the 6809 with the Z80. Its a much later design, with a much higher transistor budget. The 6809 is nothing like a PDP11, but if you want to see a current core which is, look at the MSP430.

author: iMo
author_rank: Super Contributor
timestamp: September 15, 2018, 07:15:13 am
content: Quote68000 was the PDP11, the asm mnemonics was almost the same.. 68k being my favorite one

author: ned_head
author_rank: Newbie
timestamp: February 05, 2019, 08:25:48 am
content: Hi Ron, I just registered on EEVblog after reading your post and all the replies. It's great to know so many people still love this CPU. Maybe it's too late for changes but one thing no one mentioned is the Hitachi HD6309E. They're still available on eBay but I see you're using the on-chip oscillator 6809. I'm not sure if Hitachi made a 63C09P. I've seen one ad on eBay but several for the 63C09E. I mention it not so much for the 2 or even 3MHz capability but for the presence of the illegal instruction trap: something I rued the absence of in the old days when my TCB-108 "Flexi-Plus" board would just hang without me knowing why but strongly suspecting I'd done something stupid on a von-Neumann machine.. I wish Hitachi had been able to announce that (along with the other awesome features you probably know about - 16b*16b signed multiply and 32b / 16b signed divide in particular) but I read somewhere that making it known clashed with their licensing agreement with Motorola. More accumulators, 32bit concatenated registers, bit and block transfers, a bunch of additional instructions and shorter execution times in native mode..PS. In my opinion, the best thing about the 6502 was the fact that the family of peripherals, often superior to Motorola, were bus-compatible with 68xx: The Flexi-Plus has a 6551 ACIA (with on-chip baud-rate generator unlike a 6850) and 6522 VIA's (with serial hardware and timers).http://www.6809.org.uk/dragon/6309.txt

author: grantb5
author_rank: Regular Contributor
timestamp: February 05, 2019, 03:52:50 pm
content: Thanks for posting that here. I was aware that there were improvements but had no idea they were that vast. I'm working on a HD6303 at the moment and it looks to only have a few bit manipulation instructions added over the 6801 family. Very interesting about the ACIA. The external baud rate chip was always a pain in the butt for the 6850.I would kill to have a modern flash micro based on a 6502 or 6800 or 6809 or anything similar. The HC11 is close I guess, but it's not flash as far as I know. HC12 is too oddball. Maybe an HC908 or something could fill that roll. Something with a decent amount of flash and ram... oh well, I can use an flash 8051 or ARM I guess. I did that once for an 8021 drop-in.

author: rhodges
author_rank: Frequent Contributor
timestamp: February 05, 2019, 06:20:00 pm
content: Quote from: grantb5 on February 05, 2019, 03:52:50 pmI programmed the 6809 in the early 1990's and I liked it. That is coming from earlier assembly with z80 and 8088.Now I am programming for STM8 (notably stm8s103 and stm8s105). I like STM8 architecture a lot. It has two general purpose pointers (X and Y) and a LOT of useful addressing modes, including easy offsets from SP. Want a cheap counter? "label: push #8; ...loop... dec (1, sp); jrne label". The addressing modes are very compiler friendly. There are some very useful bit operations, including branch on bit.Even though the clock is "only" 16mhz, many or most of the instructions can execute in one cycle. There are multiply and divide instructions. Most of the internal peripherals have one or two dedicated interrupt vectors. Even though the cheapest chips have only three timers, timer1 and timer2 have four and three capture or compare channels for measuring or creating pulses or as general purpose timer interrupts.An stm8s103 has 8K program flash, 1k of RAM, 640 of EEPROM. They go on ebay, mounted on a breakout board, for just over a dollar. An stm8s105 has 16k flash, 2k RAM, and 1K EEPROM, and you can buy one on a board and with a crystal, for two and a half. A USB programming adapter can cost two and a half. A USB serial adapter can cost from $1 to $1.5 The SDCC compiler is free and works great. I can even compile and program the devices from a Raspberry PI.You can do a lot of useful things with 8k, 16k, or 32k of program flash and 1k or 2k of RAM.If you are curious for more, I invite you to browse my personal and github project pages:http://www.hodges.org/rh/stm8/https://github.com/unfrozenUpdate: Here is the STM8 programmer's manual:https://www.st.com/resource/en/programming_manual/cd00161709.pdf

author: grantb5
author_rank: Regular Contributor
timestamp: February 05, 2019, 06:51:08 pm
content: Wow, that's interesting. I didn't realize other manufacturers made micros with similar programming models. I remember Cosmic from somewhere and would be tempted to try that out versus SDCC, especially if ST has an IDE of their own with compiling and debugging. With this ST-Link thing for $2+, can you set breakpoints and single-step and such? I see you mentioned simulator too. Thanks for the lead!

author: rhodges
author_rank: Frequent Contributor
timestamp: February 05, 2019, 09:11:32 pm
content: Quote from: grantb5 on February 05, 2019, 06:51:08 pmI usually just throw debugging text out the UART, but I have read that the ST-Link can do debugging. I just don't know how deep. OpenOCD might be a good place to start.I have used the Cosmic simulator, and it was handy for counting cycles. The free version was for Windows, but it ran fine on Wine

author: ron.owens
author_rank: Regular Contributor
timestamp: February 12, 2019, 10:08:54 pm
content: Quote from: ned_head on February 05, 2019, 08:25:48 amI'm glad to hear this thread was interesting enough to you to sign up. I have been absent for a while working on a Z80 design, of all things. Your post has inspired me to get back to work on the 6809 project again. I didn't get a chance to work with the Hitachi 6809 parts. I was Motorola man, back in the day. In fact, I worked at Motorola when they where manufacturing 6809s. That's how I got interested in them. I worked at the plant in Mesa, AZ and the 6809 was manufactured in Austin TX. There was an in-plant class on both the 6800 and 6809 I took. They were mostly hardware, but we got to do some assembly language programming on a D2 development board they gave us. I wish I had it now. It was fairly simple with a keypad and 7-segment displays. I wrote a four function calculator program for it during the class. I'll try to do better at posting now. I should have an updated schematic and board layout soon that i will post.

author: grantb5
author_rank: Regular Contributor
timestamp: February 12, 2019, 11:11:43 pm
content: I think I used the 6800 D2 board too (in school). I've seen stuff like this for sale on eBay or VintageComputers.com or CPU-World.com. Our second level class moved onto the 6809 and we wire-wrapped it. I think I still have it.I discovered a Japanese site, well, group of sites/individuals, that are making SBC's for these old beasts. If you Google and then Google translate SBC6809 you can find them. I just ordered 10 blank PCBs since that was the minimum, so I'll have those in the USA in a few weeks. Here is one such page:https://translate.google.com/translate?hl=en&sl=ja&u=https://vintagechips.wordpress.com/2017/12/05/sbc6809%25E3%2583%25AB%25E3%2583%25BC%25E3%2582%25BA%25E3%2582%25AD%25E3%2583%2583%25E3%2583%2588/&prev=searchAlso, I discovered a nice 68xx simulator. I've used several DOS ones in the past, and my own monitor is pretty comprehensive, but I tested the 6303 one and it emulated pretty well. Anyway, nice in that it actually works, not cute though. Unfortunately NO 6809, but the source code is available. I haven't used the 6809 much recently so I'm probably overlooking some obvious tools. I use the Baldwin Assemblers for a few different CPUs.

author: Squiddaddy
author_rank: Regular Contributor
timestamp: February 13, 2019, 06:08:38 pm
content: Ahh the 6809!!I still have a modified Color Computer 3, that supports 8MB ram, and has real serial and parallel ports.It was one of those things that they called 'NoCan' back in the day, where you removed the RF modulator box, and plugged a board into the memory expansion. The one I have is built around a Lattice chip.That and a hard drive controller, I have a pretty decent OS9 box. It's all boxed up at the moment, but man, I had a lot of fun with that thing. Built an EPROM programmer for it back in the day to modify the ROMS.Cool stuff!!!

author: DDunfield
author_rank: Regular Contributor
timestamp: February 14, 2019, 09:57:00 am
content: I too had a long love affair with the 6809 which culminated in the creation of my "D6809 Portable" which can be seen at:www.classiccmp.org/dunfield(or google "Daves Old Computers")Scroll down to the "Homebuilts" section and check out "D6809 portable".I wrote a *LOT* of code for the 09 and have made a number of resources available which might be useful to anyone playing with this part:NOTE: Any tools mentioned run under DOS, but work fine under DOSBOX for those systems which cannot naively run 16-bit DOS executables.D6809 simulator (available under "D6809 portable" page)Includes MC6809 (obviously), system ROM, video display, keyboard, disk controller/drives, serial ports.Default ROM is my CUBIX OS, but you can substitute your own.Simulator includes a debugger with disassembler, breakpoints, single-step, traceback, memory/register editors etc.NOTE: To experience running the actual D6809 system, the simulator emulates the delays inherent in starting/stepping/reading floppy drives.If you get tired of waiting for it, use the '/D' command line option to disable drive speed emulation which speeds things up greatly!CUBIX source code and porting package (available under "D6809 portable" page)Everything you need to port CUBIX to your own 6809 system.CUBIX is a simple command OS (DOS for the 6809!), but does have some nice features, over 100 system calls implemented via SWI.It includes a few applications:- Couple of editors- C compiler- Assembler- BASIC interpreter- Micro-APL interpreter- Micro-FORTH (unique native-compiled implementation)- 8080 simulator- A number of other utilitiesYou can try it out using the D6809 simulator above.Micro-C cross compiler for 6809 (Available in "DOS widgets" section of main page - "Embedded development tools" section)This is a PC hosted cross compiler for 6809 embedded systems. Reasonably complete, has a decent library.Not tied to any system/hardware, easy to get code up and running on "bare metal".NOTE: the 6809 was the first/original target for my Micro-C toolset.ASM09 cross assembler for 6809 (included in Micro-C/09 or in "XTOOLS" package)Simple and straightforward cross assembler. Outputs Motorola (S18) or Intel download records.Has a useful macro preprocessor etc.MON09 software development monitor (same place as compiler, "XTOOLS" package)This is a ROM monitor for the 6809 which includes memory dump, memory/register editors, disassembly, breakpoints, single-step etc.HDM09 hardware development monitor (Available in "DOS widgets" section of main page - "XTOOLS" package)A very simple monitor (memory read/write, loop read/write etc.) which requires NO RAM.All you need working in a ROM and UART (and you can use UART polling to debug that).DOSBOX DOS emulator (Available in "DOS widgets" section "Third party files section" near bottom)My customized version of HAL9000 Megabuild DOSBOX which I use to run DOS code under Win7/64.Enjoy,Dave

author: grantb5
author_rank: Regular Contributor
timestamp: February 14, 2019, 02:18:19 pm
content: Hi Dave. Great to have a legend around here. I'm pretty sure I still have a compiler of yours around here someplace.

author: cjs
author_rank: Contributor
timestamp: May 12, 2019, 01:19:47 pm
content: Quote from: PuterGeek on May 31, 2016, 08:36:53 pmNot in the slightest. As others have pointed out, the primary feature of the 6502 was immensely lower cost: the 6502 was released at $25 when at that time the 6800 was selling for $175. (The 6800 was quickly reduced to $69, and eventually to $39, but by that point the high-volume users of home computer microprocessors had already settled on the 6502.)The way to reduce cost was, of course, to remove things to get a smaller die, and the 6502 was generally a deficient processor compared to the 6800. Major reductions in functionality included:The second accumulator ('B' register) was removed.The stack pointer was reduced from 16 bits to 8 bits, leaving the stack to live in page 1 (0x100-0x1ff) only. That particularly hurt if you wanted to do multiprocessing.The 16-bit index register was replaced with a pair of 8-bit index registers, making life difficult if you wanted to, e.g., copy and/or transform more than a 256-byte chunk of memory.Interesting bugs were introduced, such as a broken ROR (rotate right instruction), which was rapidly fixed, and reading the wrong high address byte for JMP if the JMP address crossed a page boundary (eventually fixed in the 80s with the 65C02).The 6502 did have two improvements over the 6800, though. One was the ability to index based on an 16-bit address in the zero page with the Y register added to that, making memory-to-memory block transfer/modify operations easier (so long as they were less than 256 byte blocks!). This was done with the 16-bit index register in the 6800 but, in what in retrospect was a major design deficiency, there was only one index register so you had to save the source address after every load of a data byte in order to load the destination address, and then do the reverse to get the next source byte. The other 6502 improvement wasmuchfaster interrupt processing, perhaps the fastest of any 8-bit CPU. Much of that was due simply to saving a lot less on the stack when an interrupt occurred.The 6809 was a great improvement over both the 6800 and the 6502, but was based almost purely on improving the 6800, taking almost nothing from the 6502. For example, the block copy inconvenience described above was fixed in the obvious way: add a second 16-bit index register, thus also making this operation faster than the 6502 because it now took fewer memory loads and stores rather than more. They also added a "fast" interrupt which greatly reduced interrupt processing time by saving fewer registers, though it still wasn't as fast as the 6502. And multiprocessing became even easier and better with the careful attention they paid to supporting position-independent code, though that wasn't actually the intent of that feature. But all this made it a great platform for OS-9, probably the most sophisticated 8-bit operating system ever.Though the 6502 won the battle as far as quantity, the 6809 was still heavily used in areas where the volume was lower and the extra hardware cost was made up for by easier software development, such as arcade video games and embedded systems. It's without question one of the best if notthebest 8-bit CPUs of the 1970s and early 80s, and unless you need 6502 compatibility for some reason you'd generally be happier today using a 6809 in your retrocomputing projects.I've not programmed a 6809 since the early 80s, when I had busied myself putting together an OS-9 system based around a Radio Shack Color Computer 3. Unfortunately, events precepitated by the untimely death of my father put paid to all my 1980s computing plans and the CoCo and its peripherals were lost along the way. But I'm getting interested in this again, and I too have started to make plans to build a 6809 system, though not with hardware as sophisticated as the rather nice SBC that started this thread. My intent is to explore what might have happened in an alternate reality where LISP instead of BASIC had become the common high-level language of microcomputers in the 70s.

author: grantb5
author_rank: Regular Contributor
timestamp: May 12, 2019, 04:07:04 pm
content: I find it interesting that so many people are building up "PC's" using these 8-bitters. I come from the opposite angle where they were used in embedded systems such as synthesizers and other music gear. I don't know of any that used the 6502 , and in fact I can't recollect any 6800 based synth's either, but I'm sure they are out there.The 8-bit CPU's I see a lot of are Z80 (which I know little about), the 6809 was widely used, the 8051 family even more so (being a micro-controller and all) and the Hitachi 6303. I guess it could be argued that the 6303 is a descendant of the 6800, but as a microcontroller.I wish the synths I was working on now (for the purpose of changing features) were 6809-based, but most of them seem to be 6303. I certainly enjoy working on both the 8051 and 6303 synths, but find myself cursing at all the code it takes to do something that would be so natural and compact in the 6809.

author: cjs
author_rank: Contributor
timestamp: May 13, 2019, 02:49:21 pm
content: Quote from: grantb5 on May 12, 2019, 04:07:04 pmYes, right! That was the other major application for the 6809 that I was thinking of but forgot to put in my post. It was used in a very wide range of instruments, from the various Ensoniq synthesizers and samplers (cheap but very featureful—I loved my ESQ-1) to the midrange (Oberheim) to the high end (PPG Wave) to the super-high-end (Fairlight CMI Series II).QuoteWell, I'd say itisa 6800. It differs from what I typically think of when I think of a "microcontroller" in that it's designed around having a large (for the time) address space and the capability to easily add a lot of external peripheral logic; unlike most microcontrollers it's perfectly suited for a "real" computer. There were various other "microprocessors in microcontroller garb" as well, such as the 6508; typically these just added a bit of RAM and a few I/O pins (though the 6303X and 6303Y really went all out, expanding to 64-pin packages with serial ports, PLLs, the whole bit). But except for those where they removed pins for the sake of a smaller package (6507), these were all perfectly usable as the CPU of a "real" computer, weren't they?And for something like an arcade game or a digital synth with a sequencer, you'd need that address space and ability to integrate with a lot of external hardware.QuoteYa. The 6800 was pretty great for 1974, but there were a few mistakes they made with it (lack of a second index register!) that really hurt. But until the late 70s there weren't really any microprocessors that I can think of that didn't have those problems. The early microprocessor manufacturers did have the example of the PDP-11, which they gleefully used in the late '70s, so I can only assume that it was just lack of enough transistors that caused them to scrimp so much on registers and addressing modes in earlier days. (Though maybe the 8080 guys were just perverse. They stuck in a more reasonable number of registers but then made everything a pain to use.)

author: grantb5
author_rank: Regular Contributor
timestamp: May 14, 2019, 02:34:36 pm
content: I have a "handheld" Yamaha RCX1 remote control unit that has a 64-pin shrink DIP HD6303YP. I was kind of surprised to see such a large device in such a small, simple unit. Especially since the DX7 family uses a more basic 6303.But to bring it more on-topic, my Yamaha MEP4 has a 6809 in it. Ensoniq used the 68HC11 in some keyboard controller applications. I was heartbroken when the HC11 was released and it wasn't based on the 6809. Then the HC12 was the final blow for me and I was done with Motorola.

author: guenthert
author_rank: Frequent Contributor
timestamp: May 14, 2019, 03:26:52 pm
content: Quote from: cjs on May 12, 2019, 01:19:47 pmI can somewhat relate, but think that LISP might be a bridge too far for 8 bitters (even though I know that some implementations did exists, e.g. Inter-LISP, but I can't help wondering, what you could do with them). Much later, in the early nineties, the CLISP project managed to implement a pretty good Common Lisp compiler on various hosts, starting with Atari ST (might have been the late 4MiB version). Now Common Lisp is much more demanding than earlier, simpler members of the LISP family, but still, I fear a 64KiB address space is no good match for a language with automatic memory management. FORTH might be the more natural choice for 8 bitters and certainly easier to implement.

author: cjs
author_rank: Contributor
timestamp: November 24, 2019, 07:15:20 am
content: Quote from: guenthert on May 14, 2019, 03:26:52 pmBut we have evidence otherwise: Logo is a very LISP-y language (don't be fooled by the surface syntax changes, which actually made it harder rather than easier to learn after the first few baby steps) and was released and used on a broad range of machines.QuoteWell, almost every BASIC had automatic memory management, and certainly all the popular ones did, so I don't think that's an issue.Also, 64 KiB is sheer luxury; ideally I'd like to have a minimal version that runs on a system with 4 KiB of RAM and no ROM, just like the original 4K Micro Soft BASIC.

author: intabits
author_rank: Frequent Contributor
timestamp: November 26, 2019, 04:48:26 am
content: Someone who saw my post (#53) on the Compacta Uniboard in this thread, contacted me regarding using my photos on a Uniboard web page that he is creating.I had found and scanned the documentation by that time, and made it available to him, but forgot to also post links to it all here. Until now.More images added to imgur:-https://imgur.com/gallery/lgEpyMmI've uploaded the docs (the documentation contains some duplication) to:-https://www.filehosting.org/file/details/829492/Manuals.rarhttps://www.filehosting.org/file/details/829493/Page%20Scans.rarhttps://www.filehosting.org/file/details/829494/Schematics.rarhttps://www.filehosting.org/file/details/829495/ROMs%20n%20stuff.rarThe web page he created for the UNIBOARD is:- (not sure how complete/ready it is)http://www.sardis-technologies.com/oth6809/uniboard.htm

author: ned_head
author_rank: Newbie
timestamp: December 29, 2019, 02:41:03 am
content: I have seen a reference to the earliest Fairlight CMI (the "Quasar") that claimed to have two 6800's running in tandem but I'm not really sure if it did. (I thought it too was 6809-based but I could be wrong as it's design was started back in 1976). Certainly, all the subsequent models had pairs of 6809's as the main board (running OS-9 Level II) as well as a 6809 for every channel (known as "Channel cards"). The Series III had in addition, a 68000-based card called the "Waveform Supervisor" as well as the 6809-based main CPU and the many channel cards.

author: grantb5
author_rank: Regular Contributor
timestamp: December 29, 2019, 06:01:17 am
content: Are the Fairlight schematics or service notes available online at all. I'm guessing if it's anything like the Rhodes Chroma (also 6809 I think), the docs are a binder full.

author: oPossum
author_rank: Super Contributor
timestamp: December 29, 2019, 06:06:15 am
content: There is a service manual with schematics excluding the voice board.

author: oPossum
author_rank: Super Contributor
timestamp: December 29, 2019, 06:08:05 am
content: http://www.synthzone.com/midi/fairlight/CMI_IIx_Service_Manual.pdf

author: ned_head
author_rank: Newbie
timestamp: October 05, 2020, 11:21:03 am
content: The IIx was a great machine. The Series III had the winchester hard drive which sort of stung its "road quality" attribute but made it a far more useful studio machine..https://www.manualslib.com/download/1192332/Fairlight-Cmi-Series-Iii.html

author: schofiel
author_rank: Newbie
timestamp: January 10, 2022, 12:02:34 am
content: Ron,I've also come across your SBC for the 6809P - it's quite superb, a really nice design.Are you using Eagle?Are you considering releasing the project on Github/Lab?Have you made any progress on your layout?Finally, (sorry for all the questions), are you going to release your GAL equations?I am very impressed with this work - thanks!Sincerely,Rob Schofield

author: djrm
author_rank: Contributor
timestamp: September 19, 2024, 09:49:52 am
content: Quote from: DDunfield on February 14, 2019, 09:57:00 amI'm interested in the monitor which needs no RAM, The only one I can find on the DUnfield web site seems to need a stack ram. Is HDM09 available for download please?My old home made 6809 system isn't working perhaps due to a ram problem, this could be just the thing to get it going again.Best regards, David.edit, I have found the file I was looking for HDM09.MAC in monitors.zip it says 'requires NO RAM of any sort' great :-)

author: grantb5
author_rank: Regular Contributor
timestamp: September 19, 2024, 04:18:15 pm
content: Quote from: djrm on September 19, 2024, 09:49:52 amHi. Sorry if I missed it, what is the location of said "monitors.zip" file?

author: SteveThackery
author_rank: Super Contributor
timestamp: September 19, 2024, 06:08:29 pm
content: Does anyone here remember the Tangerine personal computer?It used a 19-inch rack with a backplane across the back, and various plug-in cards were made for it by all sorts of people - mostly hobbyists. From memory there was a CPU card based on the 6502, static RAM cards, EPROM cards, a floppy controller card, a graphics card.... Actually more than one graphics card: there was a degree of competition between some of the contributors. Probably other cards as well.Anyway, I mention it because some guy living in Norfolk designed a 6809 CPU card as a plug-in replacement for the original 6502 card. He also wrote a new and improved BIOS such that it could run the Flex OS.There was a fairly powerful word processor program for it - its name escapes me at the moment. Mine had a dual 5.25-inch floppy drive and I distinctly remember writing my own programs in 'C' for it, so there must have been a 'C' compiler, but I can't remember anything much about it. My memories of writing code centre around the really long compile times as the two floppy drives sat there grunting and clicking to each other for several minutes at a time.The floppy drives had a major design flaw: the motor torque was barely adequate to spin up the disks, so I had to operate the locking lever on the front to lift the drive from the disk, let the motor spin up, and then lock the lever again. After a year or two I shelled out some serious money for a dual 3.25-inch floppy drive, which transformed the speed of the computer.I wish I could remember the guy's name - the one in Norfolk who designed the 6809 conversion (there may have been more than one - the rack-based layout with slide-in cards lent itself to expansion and upgrades). He made his money by making dog crates; the computer stuff was a side-line.

author: pqass
author_rank: Super Contributor
timestamp: September 19, 2024, 07:11:47 pm
content: QuoteIsthisthe card?Not mentioned so far...I've gotASSIST09 monitor(with my mods for 16550) working on my SBC. I'll have to try out the other software too.

author: brucehoult
author_rank: Super Contributor
timestamp: September 19, 2024, 07:35:32 pm
content: Quote from: djrm on September 19, 2024, 09:49:52 amThat would be quite a trick on a 6809! Dead easy on any modern RISC where you've got 32 registers of 4 or 8 bytes each for storage and function call/return uses a register for the return address, not stack. And apart from having few registers, the 6809 has very little register-to-register arithmetic, and I don't remember any compares. There's ABX, and LEA .. but the rest of what I recall is memory-to-accumulator.

author: SteveThackery
author_rank: Super Contributor
timestamp: September 19, 2024, 08:11:49 pm
content: Quote from: pqass on September 19, 2024, 07:11:47 pmHey, that's him! It's coming back to me now. The "Microtan" was his re-engineering of the Tangerine to run the 6809, and my recollection was that he did a very good job. I wonder if he made any money out of it.I met him in the early '80s. I wonder if he's still alive - I'd guess he'd be pushing 90 now, or maybe older.

author: djrm
author_rank: Contributor
timestamp: September 20, 2024, 06:19:15 am
content: Quote from: grantb5 on September 19, 2024, 04:18:15 pmThe file is available in the source code downloads pagehttps://dunfield.themindfactory.com/dnldsrc.htmdirect link:https://dunfield.themindfactory.com/dnld/sc/MONITORS.ZIPI built it with the following commandsCode:MACRO HDM09.MAC >HDM09.ASMASM09 HDM09.ASM -F -S P=0HEXFMT HDM09.HEX -B w=HDM09.BIN S=2048Here is the code running in an emulator, sadly it doesn't work on my target system. I think the uart has a problem

author: djrm
author_rank: Contributor
timestamp: September 20, 2024, 06:36:08 am
content: Quote from: brucehoult on September 19, 2024, 07:35:32 pmThere are CALL and RETURN macros defined in the source listing:Code:* MACRO TO PERFORM A SUBROUTINE CALLCALLmacro\0LEAS*+6,PCRGET FOLLOWING ADDRESSJMP\1EXECUTE SUBROUTINEendmac* MACRO TO RETURN FROM SUBROUTINERETURNmacro\0JMP,SRETURN TO CALLERendmac*The subroutine call listing looks like thisCode:F800 CC 0B 9E 50 BEGINLDD#$B9Edjrm 6551 9600F803 7F C4 01 51CLR>UART+1RESET UARTF806 FD C4 02 52STD>UART+2WRITE CONFIGURATIONF809 32 8C 03 53LEAS*+6,PCRGET FOLLOWING ADDRESSF80C 7E F9 12 54JMPLFCREXECUTE SUBROUTINEF80F 8E FA 93 55LDX#HELLOHELLO MESSAGEF812 32 8C 03 56LEAS*+6,PCRGET FOLLOWING ADDRESSF815 7E F8 C6 57JMPWRSTREXECUTE SUBROUTINEF818 58 * PROMPT FOR COMMANDS & EXECUTEF818 32 8C 03 59 MAINLEAS*+6,PCRGET FOLLOWING ADDRESSF81B 7E F9 12 60JMPLFCREXECUTE SUBROUTINEF81E 8E FA BB 61LDX#PROMPTPOINT TO PROMPTF821 32 8C 03 62LEAS*+6,PCRGET FOLLOWING ADDRESSF824 7E F8 C6 63JMPWRSTREXECUTE SUBROUTINEThe return statement is JMP ,SI think a similar process had to be used on the old DEC PDP8 which has no stack.David.

author: brucehoult
author_rank: Super Contributor
timestamp: September 20, 2024, 09:53:32 am
content: Very good. That gives you one level of subroutine call. And without RAM the sp isn't useful for its normal purpose anyway. You could get a 2nd level using U, which probably isn't much used. And maybe a 3rd using Y -- though I suspect some of those subroutines might want to use Y.