16FDC + Gotek (FlashFloppy) — boots fine in FM/SD, fails every time at FM→MFM transition

[Joe Corda]

​

Greeting,
Looking for some insight on a persistent issue getting double-density CDOS images to boot on my system.   Has anyone run a Gotek/FlashFloppy setup against a 16FDC and hit the kind of behavior described below ?

I'm interested in booting CDOS and CP/M on this system;  is there a disk image I should try? 
Any guidance or suggestions would be appreciated.
Thanks
Joe

Hardware:

• Cromemco ZPU (2mhz)
• 16FDC
  
  • 16FDC DIP switches: all OFF except switch 2 (RDOS-II disabled after boot) ON
  • RDOS v2.52
  • Console connected directly to the 16FDC's onboard serial port
• 64K FlexRAM (Deramp)
• 2x Gotek drives running FlashFloppy v3.38 (configured as A/B, wired to the
  16FDC's 5.25" (34-pin) header)
• Spare boards (which are not installed):
  • TU-ART
  • (2) 16KZ memory boards

What works:

• 001BASIC_IMD.hfe
  (5.25", 40 tracks, 1 side, FM/single-density throughout, 250 kbit/s) — boots CDOS 00.20 reliably every time.

What doesn't work — every one of these fails, and they span three different sources/geometries:

• 865C1127_IMD.hfe
  (8", 77 tracks, 2 sides, global MFM with an FM-encoded boot track override on track 0/side 0, 500 kbit/s) — fails with Unable to boot / 0001 0 / Err-B A4 at track 1, sector 0, right where it would first need to decode MFM.
• CDOS253_IMD.hfe
  An 8" SSSD CDOS 2.53 image ( deramp.com archive,converted IMD→HFE via HxCFloppyEmulator) — same failure signature, same location.
• 072CDOS_IMD.hfe
  A native 5.25" DSDD CDOS image (Cromemcos GitHub repo, 40 tracks/2 sides, FM boot track + global MFM, 250 kbit/s) — doesn't error, but loops indefinitely cycling tracks 0–3, unresponsive to ESC/Enter.

[Roger Hanscom]

Hi Joe,

I've got a flash floppy "drive" working on my Cromemco box.  It will boot CP/M 2.2, CDOS, and the Z80 version of Cromix.

I've got all Cromemco hardware:  ZPU, 16FDC, and 256 Kz.  I can send you the flash floppy files I use, if you'd like.

One thing that catches my eye:

• Cromemco ZPU (2mhz)

Didn't I see (somewhere) that you can't boot DD at 2 MHz?  Could be all wet?  Correct me if I'm wrong.

Roger

 

[Joseph Corda]

Roger  .
Thanks for the reply!
Yes please send all (3) OS image files and your FF.CFG file if possible.. . 
LOL I never tried thought to try switching the cpu speed ..so I will try that tomorrow and let you know

Let me know if you need my email address to get the file to me

Joe

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[arnold.mike@talk21.com arnold.mike@talk21.com]

I recall that you need the ZPU running at 4MHz for DD 8inch operation. Likewise for IMI hard disks.

Mike

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[Joseph Corda]

Thanks Mike
I will test adjusting the cpu speed tomorrow and let you know !

Joe

[Joe Corda]

Update ..so I tried to first test with the CPU switched to 4Mhz using one of my existing disk files.. no luck 
Leaving it at 4MHz, next I tried the disk images and configs from Roger on a new USB stick..and I received the following:
Cromemco RDOS 02.52 ;BA Preparing to boot, ESC to abort Unable to boot 0001 0 Err-B A4

Cromemco RDOS 02.52

;

So I have a few thoughts:

• Is there a memory issue? I wonder if there anything special about the Cromemco 16kz cards and RDOS/CDOS boot ups ? I do have a couple 16kz card which are untested. I am using Deramp's flex RAM and I have memory for RDOS ROM range blocked off. My flex ram card have been rock solid in all my other systems and is my go to RAM card.
• Are the CDOS disks image expecting a set amount of RAM?
• I'm using the 16FDC serial console. but I wonder if these image need a TU_ART card ?

Roger ..if possible can you share your HW config CPU/RAM,FDC,serial device wiht me, maybe take a picture of your Gotek jumpers an d your 16 FDC cards .. so I can compare with my
Thanks again to Roger and Mike for your help! Joe

[Roger Hanscom]

Hi Joe,

I just remembered that I failed to tell you about READY on the 16FDC.  Do you know about that trick?  I have installed a shorting block (jumper) on the 50-pin connector to short READY to ground.  It is position 11 (counting from the cable stripe).  Any question about where the jumper goes can be sorted out by looking at the pinout for the 50-pin connector (J3?).  If you plan to use the 50-pin connector, you will have to make other arrangements to free the connector from the shorting block kludge.  Maybe a wire bodge to ground READY?

Also, the images I gave you for CDOS are obviously for a 1.2 MB HD 5.25" floppy.  Any time that the Cromemco asks about the drive, you have to tell it that it is a 8" DD.  It will never know the difference. <smile>

Roger ..if possible can you share your HW config CPU/RAM,FDC,serial device wiht me, maybe take a picture of your Gotek jumpers an d your 16 FDC cards .. so I can compare

My cofig. is pretty vanilla, other than that READY trick.  ZPU running at 4MZ,  16FDC with the stock Cromemco firmware (at C000H?).  Serial is default Cromemco from the serial port on the 16FDC.  Rather than the memory you are using (16KZ?), I've got a 256KZ in there (to support Z80 CROMIX).  CDOS and CP/M don't mind the extra memory, and just ignore it.  That's it.  Everything is in a Cromemco "System One" box.

I believe that RDOS requires some functional memory.  Have you tried a "T" command from RDOS?  Just remember to hit esc at the prompt to stop "T" from writing to your "disk".  It should show what memory is in your system, and test the drive by seeking it all over the place.

I can't tell you about the jumpers on the GoTek without tearing my System One apart.  Bad design on Cromemco's part -- very difficult to do anything with the drives without a major disassembly.  BUT, I don't remember doing anything different from the standard stuff with the GoTek.

Roger

 

[Joseph Corda]

Roger 

I did not know about the  shorting block on 50 pin connector ..  I will research that a bit and give it a try .   

No stress about the  gotek  setting I would not want you to do any disassembly..  

lol my system is currently spread across my benchAt least till I can get this  working then it will be boxed up in my Z-2D chassis 

I will let you know if the 50 pin connector READY trick works 

Thanks again 

Joe 

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[Roger Hanscom]

Good Morning, Joe,

WRT the READY thing, there's a discussion of it on Herb Johnson's excellent site (retrotechnology).

Roger

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[Mr. Null Pointer]

Hi Joe and Roger. Couple things that may or may not help.

This:

firmware (at C000H?)

is correct for all of the versions of RDOS.  A couple years back I spent a bit of time reverse engineering RDOS 3.12 and it is in the Cromemco GitHub repository. Commented source and everything. Here’s a more direct link to my dropbox:

https://www.dropbox.com/scl/fi/qzib0mr4kjp1bzghhgan0/for_joe_and_roger.lis?rlkey=91nu0oy8euhfp86yn2487rnfd&dl=0

The ’T’ command tests the memory and the floppy both. If it’s of any help the code for that starts at line 1561. There’s a table of seek destinations that it uses at line 1735, so you’d at least know what the command is <trying> to do. If you are not doing RDOS 3.12 I do recall that the 2.52 that I compared to in some cases does the same thing. 

A trick that they do for the “TX” command, by the way, is they copy RDOS from 0xC000 down to 0x0100, maps in the RAM (instead of ROM) at 0xC000, then copies RDOS back up. Interesting stuff at line 2071.

Might help out, might not, but FYI.

Bill

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[Joseph Corda]

Bill and Roger 

Thanks for the info .. 

my 16fdc is Rdos 2.52..  

I will take a look at links Bill provided to maybe see happening .. I  will also run the rdos t command

I did try Rogers Jumper for READY on the 50 pin connector between pins 22-21..  

It did change something as Rogers CDOS image now doesn’t error out but continually seems to loop .   

I need to research this further and document the tracks it reading 

Joe 

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[Mr. Null Pointer]

This one I reversed but did not really look at unless I was stuck reversing the 3.12. But if it is any help here is a link to a 2.52 listing file for ya:

https://www.dropbox.com/scl/fi/6rpcrpqhyklj539j2559j/for_joe_and_roger_252.lis?rlkey=yjrs6tuo0waw26g4n97jy0htx&dl=0

Generally it seems to me that the 3.12 is 2.52 PLUS support for hard drives and such. A lot of it is unchanged, so if you put them side-by-side maybe the test code is similar. 

Bill

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[Joseph Corda]

Thanks Bill!

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[Roger Hanscom]

I'm laughing here Bill!  I think that disassembly of RDOS 2.52 is derived from one I did many, many years ago!!

Joe -- unless you are intending to try to use a hard drive, I'd stick with RDOS 2.52 -- less complexity.  I'll send the content of my CP/M memory stick in a moment.  Maybe you can get it working?  It is a very nice version 2.2 done by (I think) "Intelligent Terminals"?  I did the flash of my GoTek a long time ago, but I think it is ver. 3.23?

The fact that your GoTek is now looping might be an encouraging sign?  Maybe I need to tear my System One apart to see how the GoTek is jumpered?

Roger

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[Roger Hanscom]

Here 'ya go, Joe.  This is the critical content of my CP/M flash stick.

I told you wrong.  In addition to the ZPU, 16FDC, and 256KZ, there is also a compact flash card in the box.  It was done by the S100computers group.  It shouldn't make any difference to what we are doing here.  If you can start up your system with CP/M 2.2, you will find a file (CFCPM.COM) which (when I run it) sets up another version of CP/M 2.2 that uses the compact flash card to establish sixteen 8 MB "drives" on a single compact flash card.  It also uses the drop in replacement for the stock CCP that I find very much more capable than the DRI one.  No matter .... if you don't have the compact flash card in your system, none of this will matter.

What happens when you run a "T" command?  Does it probe memory and then seek the GoTek all over the place?  BTW, you should be using A;; for the "T" command -- medium seek speed.

BTW, I just turned on my System One (for the first time in a long time), and was able to boot up both the CDOS flash stick, and the CP/M one.  They both work fine.

If you can get the ITC version of CP/M to work, I can send you an image of the original ITC distribution diskette, with all their software (some of it quite ancient!) on it.

Roger

[Joseph Corda]

Roger

Thanks for the files 

Sadly I don’t have s100 compact flash card..  

Hmm I did build a S100 dual SD board back a bit but never tested it ..  I may plug that in to see if I can get that workings ..  

Anyway I ran out of time today so I will run “t” tomorrow and let you know what happens 

Joe 

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[Roger Hanscom]

Hey Joe --

>> Hmm I did build a S100 dual SD board back a bit but never tested it ..

 >> I may plug that in to see if I can get that workings .. 

It's one of the most useful boards put out by the S100computers group.  However, I had a lot of trouble getting it working because I didn't fully understand the bus addressing.  I can help you with it!  The early versions had a ton of dip switches for configuration, then they put a lot of the config. stuff into programmable logic.  I struggled with that, but once I understood what was going on, I got several of my boards to work, including in the Cromemco boxes.  Tell you what -- having sixteen 8 MB "drives" is fantastic!  I've done that with a number of my S100 systems!

>> Anyway I ran out of time today so I will run “t” tomorrow and let you know what happens 

Understood -- before I retired I had too many time constraints.  Now I can work on computer projects full time. <grin>

Roger

[Bill Mahoney]

Laughing. This is very likely, Roger, since I did not make any effort to reverse the 2.52, I just ran with what was in the repository. Mostly I used it to compare what was supposed to be opcodes versus what was actually a string lurking in the middle of the code. Regardless, interesting to see what you and Joe can get going.

[Joseph Corda]

Roger ..
You nailed it   .. I'm still working full time ...but nearing retirement.. soon (hopefully) .. 
Currently I get a few hours on weeknights and weekend to "play"... 

So when I tried T on rdos 2.52  nothing is displayed and system is locked until I hit  reset

I've tested parts of memory with RDOS M and V .. moving c000 cfff to 1000 and the successfully comparing

Been trying to do a disk read  test to memory and  when I try a SSSD  it works fine.

But then DSDD file  and get Err H 34..  

;A;;;

ERR-H 34

Joe 

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[Roger Hanscom]

Hi Joe,

>> So when I tried T on rdos 2.52  nothing is displayed and system is locked until I hit  reset

OK, so "T" moves RDOS out of ROM and into SRAM/DRAM and disables the ROM.  If your memory isn't working, that won't work.  So, try "TZ".  That doesn't move RDOS, and runs directly from ROM (@C000h).

BUT, you have tested memory with RDOS "M" and "V".  So I wonder what's going on?

>> Been trying to do a disk read  test to memory and  when I try a SSSD  it works fine.

So, tell me what you are doing to do a disk read.  What are you reading from?

>> ;A;;;

>> ERR-H 34

You ought to be doing "A;;" (medium seek speed).

Try this:  reset your system and hit a few returns.  Then "esc" to get the RDOS prompt.  Then enter:   "a;;dd"  (assuming that the GoTek is your "a" drive).  This should come back with another RDOS prompt.  Then do a "b".  Let me know what happens.

Roger

[Joseph Corda]

Roger

I'm in RDOS.....

Yeah I read that T moved RDOS to RAM and ran from there.. didnt see TZ command 

Tomorrow I will have more time to try TZ along with giving you a better description of the steps Im trying to do with disk reads from RDOS

It's getting late here on the East Coast... Night !

Joe

===================

;A;;;

ERR-H 34

..

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[David Roberts]

From what I remember, the Z80 timing is more tight/critical on an opcode fetch than a memory read or write.

As a result (if the memory is borderline), programs can fail when running out of RAM whereas they work when running out of ROM.

They are fetching opcodes from RAM, which have the tighter timing requirements.

Also, the memory tests are pretty basic in themselves - and will only really catch 'stuck bits'. A more complete DRAM memory test (such as the MARCH-C) should catch more esoteric DRAM failures. But, here is the rub, it will have to execute out of the DRAM you are testing (unless you are able to ROM it of course).

Dave

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[Mr. Null Pointer]

This is correct as I remember it as well. An instruction fetch puts the PC on the bus at T1 and reads the opcode at the end of T2 (a clock later). A memory read puts the address on the bus and reads the data bus in T3 (two clocks later). So the opcode fetches are “faster” - but not really because …

An opcode fetch takes four clocks and a data read only takes three. For an opcode, it’s (loosely described) PC on the bus, read the opcode, refresh cycle, refresh cycle. Four clocks. But there’s no refresh on a data read so that one (loosely) is address on the bus, extra clock goes by, read the data.

Misleading, right? Instruction fetches take longer but have shorter timing requirements, while data reads don’t take as long but are a clock longer in terms of reading the data bus. So the mystery for me now is why ROM would work. Does it have a shorter propagation delay before presenting the opcode or something? 

Probably more information than we need here but it’s entertaining to me to “listen in” on your progress!

Bill

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[arnold.mike@talk21.com arnold.mike@talk21.com]

Bill

The usual way is to AND M1 and MREQ for enabling the memory. This gives slightly longer for memory to react than simply relying on MREQ alone.

For normal ROMs (slower than RAM) there is usually a wait state inserted. I'm in Canada at the moment so don't have access to the FDC circuit diagrams to confirm.

Mike

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[arnold.mike@talk21.com arnold.mike@talk21.com]

Addendum. M1 low has to be decoded with IORQ high to avoid confusion with interrupt ack.

From: Mr. Null Pointer
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[Peter Higgins]

Joe - is all your testing being done with the 64K FlexRAM?

Cromemco's systems equipped with 64K of RAM (for example, using 4 16KZ RAM boards) are designed to block out the memory region occupied by the RDOS ROM immediately after power-up. After the RDOS boot command is executed the RDOS ROM is disabled and the previously blocked-off RAM space is enabled - a feature not supported by the FlexRAM.

If you want to use a non-Cromemco S100 64K RAM board to run Cromemco DOS, you need to implement a workaround which has been described in previous discussions in this forum. Basically, you need to route the Cromemco floppy controller RDOS ROM enable signal to an unused S100 signal line - and you cannot use the dedicated S100 /PHANTOM line since it is used for other purposes in a Cromemco system. You then need to feed that signal line from the bus to the /PHANTOM input on the FlexRAM board.

An alternative is to use CDOSGEN to configure CDOS for a smaller RAM size - say 32K or 48K. Then CDOS will simply ignore the upper 16K of RAM where you have created a permanent "hole" on the FlexRAM 64K to accommodate for the RDOS ROM.

Another thing regarding CDOSGEN - if your Goteks are configured as physical drives A and B and you are booting an 8" disk image, make sure that CDOS has been gen'ed to assign drives A and B for drive type "L" (ie, large). Or if booting from a 5.25" disk image, that CDOS has been gen'ed for drive type "S". Forgetting to do this is a common reason for getting the "Unable to boot" error message you are seeing.

[David Roberts]

It is the access time that gets you.

Don't forget that you can s t r e t c h the cycles by the system adding wait states to them.

Either the ROM is a fast enough, or the circuitry inserts wait states into the ROM cycles.

Who's memory boards have you got installed anyhow?

When I brought up my Z2 I had a collection of unknown boards. Some boards worked, some didn't, and some were iffy!

I also found some backplane slots worked and others didn't...

With a bit of trial and error - and throughly documenting what I was doing - I managed to get a set of boards in slots that worked.

I also believe that I had fun with the T and TZ commands - but I would have to check my notes about this.

Dave

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[Joseph Corda]

Peter 

Yes  still using flex ram. I only have 1 16kz that working ..  I did read about Rdos/cdos and ram  being swapped.  Last  week  I did try to block out upper ram c000-ffff from flex ram card and configured my 16kz to sit there. And then installed it .. at that pint It didnt seem to help … I think I will try that again..  

I did run tz and got output below ..  the first  run was using the sssd image ( that does boots)  the 2nd run is using  Rogers cdos that I get a err h-34

You can see that it fails when testing  c000  ram which I expected 

 Btw I appreciate all the input from the group 

Joe 

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[Amardeep Chana]

I skimmed through the replies to see if anyone had mentioned data separator calibration and didn't see anything.  Sorry if I missed that.  There's an adjustment on the 16FDC I believe it's a small control pot on the upper left corner of the board. That controls the data separator window adjustment.  If it has drifted...which after all these decades is very likely...it may still work with FM since timing is much less of an issue but fail with MFM which has to discern between three time intervals and so the timing is quite tight.

You might want to get a scope on the test point (it's all described in the manual) and adjust it to I believe 1.000MHz.  Just something to validate since you might be fighting this potential underlying condition.

Best regards,

Amardeep

[wpe...@brainless.org]

Hi,

 

I have three Cromemco 16K RAM boards for sale/trade in my stash: 

https://www.brainless.org/Altair/Repository.html#section23

 

 

 

 

 

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From: crom...@googlegroups.com <crom...@googlegroups.com> On Behalf Of Joseph Corda
Sent: Sunday, August 2, 2026 2:48 PM
To: crom...@googlegroups.com
Subject: Re: 16FDC + Gotek (FlashFloppy) — boots fine in FM/SD, fails every time at FM→MFM transition

 

Peter 

To view this discussion visit https://groups.google.com/d/msgid/cromemco/CAACXqMfuF3cyMsFY-2TfRFMmiE5WRia31N6%2BCvnid8HcpedfiQ%40mail.gmail.com.

[arnold.mike@talk21.com arnold.mike@talk21.com]

An observation. It appears that you have made a 4k hole in ram for RDOS. I think that later RDOS is 8k but cannot remember when it changed.

From: Joseph Corda
Sent: Aug 2, 2026 at 5:48 PM
To: crom...@googlegroups.com
Subject: Re: 16FDC + Gotek (FlashFloppy) — boots fine in FM/SD, fails every time at FM→MFM transition

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[Peter Higgins]

As expected, the TZ command will work with the 64K FlexRAM board.

The T command will not work with the 64K FlexRAM board since the T command copies the RDOS ROM to low RAM, disables the RDOS ROM and enables the RAM space it occupied, tests that RAM, then copies the contents the RDOS code from low RAM to C000h. Since your 64K FlexRAM board is not configured for 64K of contiguous RAM, the RDOS T command will hang.

Configuring your system with the bottom 48K of RAM provided by the FlexRAM board, and the upper 16 K of RAM provided by the 16KZ RAM board, should work. Make sure you configure that upper memory block of 16KZ RAM correctly per the manual:

- origin C000h

- bank 0

- board not selected on power-up or reset

I strongly suspect the problem you are having are primarily related to the RAM board you are using, and your system configuration. Amardeep raises a good point above re calibration of the data separator on the 16FDC board but unless you know what you are doing (ie you have an oscilloscope and have thoroughly read the section of the manual detailing the process) don't mess with it. 

[Peter Higgins]

On Sunday, August 2, 2026 at 4:02:30 PM UTC-7 Mike Arnold wrote:

An observation. It appears that you have made a 4k hole in ram for RDOS. I think that later RDOS is 8k but cannot remember when it changed.

RDOS 2.52 on the 16FDC is a 4K ROM.

RDOS 3.08 and 3.12 (which allowed for booting from the WDI and STDC hard drives respectively) are 8K ROMs. 

[Joseph Corda]

Peter...

Yeah when I block out the RAM on the FLERAM card for RDOS I recall verifying it was 4k
Now as it was pointed out about RDOS moving out of memory I'm going to try my 16KZ card in upper memory and see how that works..with TZ

I will confirm that the 16KZ i s configured as describe

- origin C000h

- bank 0

- board not selected on power-up or reset

Amardeep .. Thanks for the suggestion.. I will review the "data separator calibration" in the manual but for now I'm going to hold off and try some of the simpler fixes first.

Again thanks to everyone for the replies !

Joe

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[Roger Hanscom]

Hi Joe,

Sorry, I've been away from my computer most of the day.

One thing that bugs me.  You are trying to boot the GoTek image with the wrong seek speed.  I also get Err-34 if I try to boot up with a;;; (three semicolons).  You MUST use the medium seek speed when using my GoTek stuff (i.e. a;; (two semicolons)).  It is emulating a 5.25" HD floppy.  Using x;; is IMPORTANT (where x is the drive id for your GoTek).

Give that a try and see what happens.

Roger

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[Joseph Corda]

Thanks Roger..

I will try with 2 semicolons tonight (as I'm currently at work) and let you know

Joe

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[Roger Hanscom]

Hi Joe,

Here's a log of several boot attempts on my SystemOne (my added comments in brackets):

[normal default boot]

Preparing to boot, ESC to abort

Standby
       COPYRIGHT (C) 1979, DIGITAL RESEARCH   
System Addresses:
BDOS: DC00
BIOS: EA00
FDC : F000
CRT : FA00

A>dir
PIP     .COM  :  RDOS    .COM  :  CFCPM   .COM  :  CPMLOAD .COM
CFPSYS  .COM  :  CFUTIL  .COM  :  CPMVER  .COM  :  CRDMP   .COM
D       .COM  :  DU314   .COM  :  DUMPX   .COM  :  FIND    .COM
ARROW   .COM  :  HXIN    .COM  :  HXIN    .Z80  :  IDE     .COM
IDEUTIL .COM  :  L80     .COM  :  LOAD    .COM  :  M80     .COM
MYIDE   .COM  :  NSWP    .COM  :  REWORK  .COM  :  SPEW    .COM
STAT    .COM  :  SUDOKU  .COM  :  XMODEM  .CFG  :  XMODEM  .COM
Z8E     .COM  :  ZCPRDEMO.COM  :  ZDE16   .COM  :  ZSID    .COM
FREE    .COM  :  TUART   .COM  :  INIT    .COM  :  CDOSI   .COM
A>

[attempt to boot with fast seek (one semicolon)]

Preparing to boot, ESC to abort

Cromemco RDOS 02.52
;a;dd

[hangs]

[attempt to boot with slow seek (three semicolons)]

Preparing to boot, ESC to abort

Cromemco RDOS 02.52
;a;;;dd
Err-H 34
A;;;

[normal boot via "t" RDOS option]

Preparing to boot, ESC to abort

Cromemco RDOS 02.52
;t

Memory: 0 1 2 3 4 5 6 7 8 9 A B C D E F
       ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
Specify disk (eg, A; or A;; or A;;;) a;;
Seek tests:
01:OK 02:OK 03:OK 04:OK 05:OK
06:OK 07:OK 08:OK 09:OK 00:OK
27:OK 00:OK 15:OK 00:OK 01:OK
Restore:OK
27:OK
Read/Write tests
Data read OK
Write test MAY DESTROY data
ESC=abort RETURN=proceed  
A;;b
Preparing to boot, ESC to abort

Standby
       COPYRIGHT (C) 1979, DIGITAL RESEARCH   
System Addresses:
BDOS: DC00
BIOS: EA00
FDC : F000
CRT : FA00

A>dir
PIP     .COM  :  RDOS    .COM  :  CFCPM   .COM  :  CPMLOAD .COM
CFPSYS  .COM  :  CFUTIL  .COM  :  CPMVER  .COM  :  CRDMP   .COM
D       .COM  :  DU314   .COM  :  DUMPX   .COM  :  FIND    .COM
ARROW   .COM  :  HXIN    .COM  :  HXIN    .Z80  :  IDE     .COM
IDEUTIL .COM  :  L80     .COM  :  LOAD    .COM  :  M80     .COM
MYIDE   .COM  :  NSWP    .COM  :  REWORK  .COM  :  SPEW    .COM
STAT    .COM  :  SUDOKU  .COM  :  XMODEM  .CFG  :  XMODEM  .COM
Z8E     .COM  :  ZCPRDEMO.COM  :  ZDE16   .COM  :  ZSID    .COM
FREE    .COM  :  TUART   .COM  :  INIT    .COM  :  CDOSI   .COM
A>

Roger

[Joseph Corda]

Roger.. 
These will be helpful for comparison..

This evening my plan is to do the steps below ...and I will report back.

Thanks

Joe

• Adjust my MEM setup...
• Set the Flexram card to only cover 0000-BFFF
• Iinstall my 16KZ card from C000-FFFF
• Run TZ test to see if it pases RAM test
• Run boot attempts using the options you showed in your testing
  
  

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[Roger Hanscom]

>> This evening my plan is to do the steps below ...and I will report back.

Just try to remember, Joe ... you might think of the GoTek as a 5.25" 360k device on a 34-pin cable, but in this case it is NOT.  I know nothing about floppies, but they say that the 5.25" HD floppy drive was first developed by the Japanese to replace old, failing(?) 8" drives.  It is supposed to be entirely, or almost entirely, similar to an 8" drive (electrically speaking).  The GoTek config. stuff I sent makes your drive behave like a 5.25" HD drive, and by extension, an 8" drive.  There are at least a few times that will come into play:  1) setting the boot seek speed, 2) in CDOS if you want to INIT a *real* floppy on a HD drive (you reply to the prompts as if it is an 8" drive), and 3) booting Z80 CROMIX, you will be asked what the boot device is (you must reply that it is a full sized (8") drive if you are booting from the GoTek).  There may be more, but those are the ones I remember off the top of my head.

Roger

[Joseph Corda]

Greetings...  
Well,  " IT'S ALIVE ! "  and so far I have been able to boot multiple CDOS image files without issue.   

It turned out to be a combination things:

• Memory 
• Install 16KZ at C000-FFFF
• configured bank 0
• set "Board select to off")
• Flex64K at 0000-BFFF
• RDOS/GOTEK
• Setting the proper seek speed for gotek 
  (as Roger suggested A;;)

Next on my radar for this system is:

• Finding a CP/M image I can boot on the system
• Install at least one real floppy drive alongside a gotek. 
• Maybe locate a Cromemco memory card to properly run Cromix 
  (I need to research this more to find out what I really need).

Thanks again for all the support and suggestions.. It is greatly appreciated !

Joe

[Roger Hanscom]

That's great news, Joe!!!!

• Finding a CP/M image I can boot on the system

Did you get the IDT CP/M stuff I sent?  If not, I can send it again.  If you can boot CDOS with your current config., you should be able to boot that version as well (but it might need a full 64k of memory?).  It's the *best* version of CP/M 2.2 that I have found for the Cromemco!

• Maybe locate a Cromemco memory card to properly run Cromix 
  

I *think* you will need (for Z80 CROMIX) 64k for system memory and then another 64k for each user?  I have a flash stick for Z80 CROMX that works for my SystemOne.  When you are ready, I can send that too.

Roger

[Peter Higgins]

On Monday, August 3, 2026 at 6:09:17 PM UTC-7 norwestrzh wrote

• Maybe locate a Cromemco memory card to properly run Cromix 
  

I *think* you will need (for Z80 CROMIX) 64k for system memory and then another 64k for each user?

 There is a table in the "Cromix System Administrator's Manual" that details the hardware requirements for running Z80 Cromix. The minimum requirement is 128K of RAM for one user (ie two 64KZ boards, or one 256KZ board) and 64K of RAM for each additional user.

[Joseph Corda]

Roger

LOL...  I forgot you sent me ITC CP/M Gotek files..   I have them on a usb stick and will try them tomorrow evening.  If they work .. I may ask you for the full ITC CP/M disk image you mentioned

BTW I had the good fortune to purchase both a 64kz and a 64kz-II at what Ifelt was a reasonable price.. of course all untested ;-)  .  Once they arrive I will try them out.... 

As for Cromix I read somewhere the 64kz and 64kz-II can be used together to get booted and allow 1 user connected, again I read that ...but not sure if that is a true statement.
Honestly the best solution is to keep an eye out for a 256KZ card like you have.  Anyways, I still have a lot to research before I go down the Cromix path ..but I do want to get there. 

Joe

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[Joseph Corda]

Thanks Peter

Yeah I haven't read up on Cromix but will plan to do so soon..
Joe

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[Peter Higgins]

On Monday, August 3, 2026 at 6:47:41 PM UTC-7 Joe Corda wrote:

As for Cromix I read somewhere the 64kz and 64kz-II can be used together to get booted and allow 1 user connected, again I read that ...but not sure if that is a true statement.

That is correct. These two versions of the 64KZ are functionally equivalent, and with both boards installed you will have ample RAM to run single-user Z80 Cromix. 

[Roger Hanscom]

Speaking of the 256KZ ....

I seem to remember a discussion in this group about the PROM on the board that isn't necessary for use in a 68k Cromix systems, but is necessary for Z80 Cromix.  In fact, I believe that there are two distinct PROMS -- one for the first 256KZ board (supporting the system and 3 users), and the other for a second 256KZ board (if there was one) to support 4(?) additional users?  I think that the PROMs are now obsolete and a number of possible substitutes were brought up.  Was there ever a consensus reached about how to replace these PROMs?  OR, a way to "read out" the content in order to figure out an approach to support 256KZ memory boards in a Z80 CROMIX install?

It was a while ago, and my memory is pretty fuzzy on the subject.

Roger

[Peter Higgins]

On Monday, August 3, 2026 at 8:29:48 PM UTC-7 norwestrzh wrote:

Speaking of the 256KZ ....

Was there ever a consensus reached about how to replace these PROMs?  OR, a way to "read out" the content in order to figure out an approach to support 256KZ memory boards in a Z80 CROMIX install?

See this discussion, and the attached ZIP file:

https://groups.google.com/g/cromemco/c/7S3WWjgP-Ko/m/H1PfVuS2AgAJ

[Joseph Corda]

Kind of a Cromemco newbie question..  but are the Cromemco DPU (68000/z80) boards ever available for sale or are they "unobtainium" ? 

Joe

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[David Roberts]

They do come up occasionally (I bought one back in 2022 - I was lucky) but they are fairly unobtainable...

Dave

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[Joseph Corda]

Thanks Dave .. yeah I will keep an eye out

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[Peter Higgins]

The DPU board does come up on eBay but rarely - maybe once or twice a year. A DPU was sold literally within hours of being listed just 4 weeks ago, with a "best offer" price of $350.

[Joseph Corda]

Thanks Peter  .. that gives me a feeding of the price point as well  !  . 
I will do a ebay search for completed/sold DPU and look for more history 

Joe

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[Roger Hanscom]

Thanks, Peter, for the link to the .zip file (re: 256KZ)

>>See this discussion, and the attached ZIP file:

>> https://groups.google.com/g/cromemco/c/7S3WWjgP-Ko/m/H1PfVuS2AgAJ

By chance, does anybody have the .JED file for the first PROM (74947).  I'm not familiar with the language used in the .PLD files contained in the .ZIP (I can do PALASM), so I'm not able to generate it myself.

Roger

[Euan Webster]

WinCUPL will do the conversion I think. I did one a few months back, but for an entirely different system...that I can't even remember now! Age is a sod :-D

[Rich Camarda]

Is this what you need Roger?

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[Peter Higgins]

Rich - does your PLD code use WinCUPL syntax, or PALASM syntax ?

[Roger Hanscom]

>> Is this what you need Roger?

That's exactly what I need, Rich.  Thanks so much!!!

BTW, what is the code in your .PLD files?  I've never seen it before.

Roger

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[Rich Camarda]

I am using WinCUPL. This is a JED file for the prom, and I also have .PLD files for the 22V10 GALS I created f to replace the proms.

Rich

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